This fix solves this error, when calling kselftest with targets "net/rds":

The error was found by running tests manually with the command:
make kselftest TARGETS="net/rds"

The patch also specifies to import ip() function from the utils module.
Signed-off-by: Alessandro Zanni <alessandro.zanni87@gmail.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Link: https://patch.msgid.link/20241010194421.48198-1-alessandro.zanni87@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Fix the build warnings when CONFIG_FSL_ENETC_MDIO is not enabled.
The detailed warnings are shown as follows.

include/linux/fsl/enetc_mdio.h:62:18: warning: no previous prototype for function 'enetc_hw_alloc' [-Wmissing-prototypes]
      62 | struct enetc_hw *enetc_hw_alloc(struct device *dev, void __iomem *port_regs)
         |                  ^
include/linux/fsl/enetc_mdio.h:62:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
      62 | struct enetc_hw *enetc_hw_alloc(struct device *dev, void __iomem *port_regs)
         | ^
         | static
8 warnings generated.

Fixes: 6517798d ("enetc: Make MDIO accessors more generic and export to include/linux/fsl")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202410102136.jQHZOcS4-lkp@intel.com/Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241011030103.392362-1-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Wei Fang says:

====================
net: enetc: fix some issues of XDP

We found some bugs when testing the XDP function of enetc driver,
and these bugs are easy to reproduce. This is not only causes XDP
to not work, but also the network cannot be restored after exiting
the XDP program. So the patch set is mainly to fix these bugs. For
details, please see the commit message of each patch.

v1: https://lore.kernel.org/bpf/20240919084104.661180-1-wei.fang@nxp.com/
v2: https://lore.kernel.org/netdev/20241008224806.2onzkt3gbslw5jxb@skbuf/
v3: https://lore.kernel.org/imx/20241009090327.146461-1-wei.fang@nxp.com/
====================

Link: https://patch.msgid.link/20241010092056.298128-1-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

When running "xdp-bench tx eno0" to test the XDP_TX feature of ENETC
on LS1028A, it was found that if the command was re-run multiple times,
Rx could not receive the frames, and the result of xdp-bench showed
that the rx rate was 0.

root@ls1028ardb:~# ./xdp-bench tx eno0
Hairpinning (XDP_TX) packets on eno0 (ifindex 3; driver fsl_enetc)
Summary                      2046 rx/s                  0 err,drop/s
Summary                         0 rx/s                  0 err,drop/s
Summary                         0 rx/s                  0 err,drop/s
Summary                         0 rx/s                  0 err,drop/s

By observing the Rx PIR and CIR registers, CIR is always 0x7FF and
PIR is always 0x7FE, which means that the Rx ring is full and can no
longer accommodate other Rx frames. Therefore, the problem is caused
by the Rx BD ring not being cleaned up.

Further analysis of the code revealed that the Rx BD ring will only
be cleaned if the "cleaned_cnt > xdp_tx_in_flight" condition is met.
Therefore, some debug logs were added to the driver and the current
values of cleaned_cnt and xdp_tx_in_flight were printed when the Rx
BD ring was full. The logs are as follows.

[  178.762419] [XDP TX] >> cleaned_cnt:1728, xdp_tx_in_flight:2140
[  178.771387] [XDP TX] >> cleaned_cnt:1941, xdp_tx_in_flight:2110
[  178.776058] [XDP TX] >> cleaned_cnt:1792, xdp_tx_in_flight:2110

From the results, the max value of xdp_tx_in_flight has reached 2140.
However, the size of the Rx BD ring is only 2048. So xdp_tx_in_flight
did not drop to 0 after enetc_stop() is called and the driver does not
clear it. The root cause is that NAPI is disabled too aggressively,
without having waited for the pending XDP_TX frames to be transmitted,
and their buffers recycled, so that xdp_tx_in_flight cannot naturally
drop to 0. Later, enetc_free_tx_ring() does free those stale, unsent
XDP_TX packets, but it is not coded up to also reset xdp_tx_in_flight,
hence the manifestation of the bug.

One option would be to cover this extra condition in enetc_free_tx_ring(),
but now that the ENETC_TX_DOWN exists, we have created a window at
the beginning of enetc_stop() where NAPI can still be scheduled, but
any concurrent enqueue will be blocked. Therefore, enetc_wait_bdrs()
and enetc_disable_tx_bdrs() can be called with NAPI still scheduled,
and it is guaranteed that this will not wait indefinitely, but instead
give us an indication that the pending TX frames have orderly dropped
to zero. Only then should we call napi_disable().

This way, enetc_free_tx_ring() becomes entirely redundant and can be
dropped as part of subsequent cleanup.

The change also refactors enetc_start() so that it looks like the
mirror opposite procedure of enetc_stop().

Fixes: ff58fda0 ("net: enetc: prioritize ability to go down over packet processing")
Cc: stable@vger.kernel.org
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241010092056.298128-5-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The Tx BD rings are disabled first in enetc_stop() and the driver
waits for them to become empty. This operation is not safe while
the ring is actively transmitting frames, and will cause the ring
to not be empty and hardware exception. As described in the NETC
block guide, software should only disable an active Tx ring after
all pending ring entries have been consumed (i.e. when PI = CI).
Disabling a transmit ring that is actively processing BDs risks
a HW-SW race hazard whereby a hardware resource becomes assigned
to work on one or more ring entries only to have those entries be
removed due to the ring becoming disabled.

When testing XDP_REDIRECT feautre, although all frames were blocked
from being put into Tx rings during ring reconfiguration, the similar
warning log was still encountered:

fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #6 clear
fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #7 clear

The reason is that when there are still unsent frames in the Tx ring,
disabling the Tx ring causes the remaining frames to be unable to be
sent out. And the Tx ring cannot be restored, which means that even
if the xdp program is uninstalled, the Tx frames cannot be sent out
anymore. Therefore, correct the operation order in enect_start() and
enect_stop().

Fixes: ff58fda0 ("net: enetc: prioritize ability to go down over packet processing")
Cc: stable@vger.kernel.org
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241010092056.298128-4-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

When testing the XDP_REDIRECT function on the LS1028A platform, we
found a very reproducible issue that the Tx frames can no longer be
sent out even if XDP_REDIRECT is turned off. Specifically, if there
is a lot of traffic on Rx direction, when XDP_REDIRECT is turned on,
the console may display some warnings like "timeout for tx ring #6
clear", and all redirected frames will be dropped, the detailed log
is as follows.

root@ls1028ardb:~# ./xdp-bench redirect eno0 eno2
Redirecting from eno0 (ifindex 3; driver fsl_enetc) to eno2 (ifindex 4; driver fsl_enetc)
[203.849809] fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #5 clear
[204.006051] fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #6 clear
[204.161944] fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #7 clear
eno0->eno2     1420505 rx/s       1420590 err,drop/s      0 xmit/s
  xmit eno0->eno2    0 xmit/s     1420590 drop/s     0 drv_err/s     15.71 bulk-avg
eno0->eno2     1420484 rx/s       1420485 err,drop/s      0 xmit/s
  xmit eno0->eno2    0 xmit/s     1420485 drop/s     0 drv_err/s     15.71 bulk-avg

By analyzing the XDP_REDIRECT implementation of enetc driver, the
driver will reconfigure Tx and Rx BD rings when a bpf program is
installed or uninstalled, but there is no mechanisms to block the
redirected frames when enetc driver reconfigures rings. Similarly,
XDP_TX verdicts on received frames can also lead to frames being
enqueued in the Tx rings. Because XDP ignores the state set by the
netif_tx_wake_queue() API, so introduce the ENETC_TX_DOWN flag to
suppress transmission of XDP frames.

Fixes: c33bfaf9 ("net: enetc: set up XDP program under enetc_reconfigure()")
Cc: stable@vger.kernel.org
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241010092056.298128-3-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The xdp_drops statistic indicates the number of XDP frames dropped in
the Rx direction. However, enetc_xdp_drop() is also used in XDP_TX and
XDP_REDIRECT actions. If frame loss occurs in these two actions, the
frames loss count should not be included in xdp_drops, because there
are already xdp_tx_drops and xdp_redirect_failures to count the frame
loss of these two actions, so it's better to remove xdp_drops statistic
from enetc_xdp_drop() and increase xdp_drops in XDP_DROP action.

Fixes: 7ed2bc80 ("net: enetc: add support for XDP_TX")
Cc: stable@vger.kernel.org
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241010092056.298128-2-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

When port mirroring is added to a port, the bit position of the source
port, needs to be written to the register ANA_AC_PROBE_PORT_CFG.  This
register is replicated for n_ports > 32, and therefore we need to derive
the correct register from the port number.

Before this patch, we wrongly calculate the register from portno /
BITS_PER_BYTE, where the divisor ought to be 32, causing any port >=8 to
be written to the wrong register. We fix this, by using do_div(), where
the dividend is the register, the remainder is the bit position and the
divisor is now 32.

Fixes: 4e50d72b ("net: sparx5: add port mirroring implementation")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241009-mirroring-fix-v1-1-9ec962301989@microchip.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

After commit 8d7017fd ("blackhole_netdev: use blackhole_netdev to
invalidate dst entries"), blackhole_netdev was introduced to invalidate
dst cache entries on the TX path whenever the cache times out or is
flushed.

When two UDP sockets (sk1 and sk2) send messages to the same destination
simultaneously, they are using the same dst cache. If the dst cache is
invalidated on one path (sk2) while the other (sk1) is still transmitting,
sk1 may try to use the invalid dst entry.

         CPU1                   CPU2

      udp_sendmsg(sk1)       udp_sendmsg(sk2)
      udp_send_skb()
      ip_output()
                                             <--- dst timeout or flushed
                             dst_dev_put()
      ip_finish_output2()
      ip_neigh_for_gw()

This results in a scenario where ip_neigh_for_gw() returns -EINVAL because
blackhole_dev lacks an in_dev, which is needed to initialize the neigh in
arp_constructor(). This error is then propagated back to userspace,
breaking the UDP application.

The patch fixes this issue by assigning an in_dev to blackhole_dev for
IPv4, similar to what was done for IPv6 in commit e5f80fcf ("ipv6:
give an IPv6 dev to blackhole_netdev"). This ensures that even when the
dst entry is invalidated with blackhole_dev, it will not fail to create
the neigh entry.

As devinet_init() is called ealier than blackhole_netdev_init() in system
booting, it can not assign the in_dev to blackhole_dev in devinet_init().
As Paolo suggested, add a separate late_initcall() in devinet.c to ensure
inet_blackhole_dev_init() is called after blackhole_netdev_init().

Fixes: 8d7017fd ("blackhole_netdev: use blackhole_netdev to invalidate dst entries")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/3000792d45ca44e16c785ebe2b092e610e5b3df1.1728499633.git.lucien.xin@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Pull networking fixes from Jakub Kicinski:
 "Including fixes from bluetooth and netfilter.

  Current release - regressions:

   - dsa: sja1105: fix reception from VLAN-unaware bridges

   - Revert "net: stmmac: set PP_FLAG_DMA_SYNC_DEV only if XDP is
     enabled"

   - eth: fec: don't save PTP state if PTP is unsupported

  Current release - new code bugs:

   - smc: fix lack of icsk_syn_mss with IPPROTO_SMC, prevent null-deref

   - eth: airoha: update Tx CPU DMA ring idx at the end of xmit loop

   - phy: aquantia: AQR115c fix up PMA capabilities

  Previous releases - regressions:

   - tcp: 3 fixes for retrans_stamp and undo logic

  Previous releases - always broken:

   - net: do not delay dst_entries_add() in dst_release()

   - netfilter: restrict xtables extensions to families that are safe,
     syzbot found a way to combine ebtables with extensions that are
     never used by userspace tools

   - sctp: ensure sk_state is set to CLOSED if hashing fails in
     sctp_listen_start

   - mptcp: handle consistently DSS corruption, and prevent corruption
     due to large pmtu xmit"

* tag 'net-6.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (87 commits)
  MAINTAINERS: Add headers and mailing list to UDP section
  MAINTAINERS: consistently exclude wireless files from NETWORKING [GENERAL]
  slip: make slhc_remember() more robust against malicious packets
  net/smc: fix lacks of icsk_syn_mss with IPPROTO_SMC
  ppp: fix ppp_async_encode() illegal access
  docs: netdev: document guidance on cleanup patches
  phonet: Handle error of rtnl_register_module().
  mpls: Handle error of rtnl_register_module().
  mctp: Handle error of rtnl_register_module().
  bridge: Handle error of rtnl_register_module().
  vxlan: Handle error of rtnl_register_module().
  rtnetlink: Add bulk registration helpers for rtnetlink message handlers.
  net: do not delay dst_entries_add() in dst_release()
  mptcp: pm: do not remove closing subflows
  mptcp: fallback when MPTCP opts are dropped after 1st data
  tcp: fix mptcp DSS corruption due to large pmtu xmit
  mptcp: handle consistently DSS corruption
  net: netconsole: fix wrong warning
  net: dsa: refuse cross-chip mirroring operations
  net: fec: don't save PTP state if PTP is unsupported
  ...

Merge tag 'trace-ringbuffer-v6.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fix from Steven Rostedt:
 "Ring-buffer fix: do not have boot-mapped buffers use CPU hotplug
  callbacks

  When a ring buffer is mapped to memory assigned at boot, it also
  splits it up evenly between the possible CPUs. But the allocation code
  still attached a CPU notifier callback to this ring buffer. When a CPU
  is added, the callback will happen and another per-cpu buffer is
  created for the ring buffer.

  But for boot mapped buffers, there is no room to add another one (as
  they were all created already). The result of calling the CPU hotplug
  notifier on a boot mapped ring buffer is unpredictable and could lead
  to a system crash.

  If the ring buffer is boot mapped simply do not attach the CPU
  notifier to it"

* tag 'trace-ringbuffer-v6.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Do not have boot mapped buffers hook to CPU hotplug

Pull btrfs fixes from David Sterba:

 - update fstrim loop and add more cancellation points, fix reported
   delayed or blocked suspend if there's a huge chunk queued

 - fix error handling in recent qgroup xarray conversion

 - in zoned mode, fix warning printing device path without RCU
   protection

 - again fix invalid extent xarray state (6252690f), lost due to
   refactoring

* tag 'for-6.12-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix clear_dirty and writeback ordering in submit_one_sector()
  btrfs: zoned: fix missing RCU locking in error message when loading zone info
  btrfs: fix missing error handling when adding delayed ref with qgroups enabled
  btrfs: add cancellation points to trim loops
  btrfs: split remaining space to discard in chunks

Pull nfsd fixes from Chuck Lever:

 - Fix NFSD bring-up / shutdown

 - Fix a UAF when releasing a stateid

* tag 'nfsd-6.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  nfsd: fix possible badness in FREE_STATEID
  nfsd: nfsd_destroy_serv() must call svc_destroy() even if nfsd_startup_net() failed
  NFSD: Mark filecache "down" if init fails

Pull xfs fixes from Carlos Maiolino:

 - A few small typo fixes

 - fstests xfs/538 DEBUG-only fix

 - Performance fix on blockgc on COW'ed files, by skipping trims on
   cowblock inodes currently opened for write

 - Prevent cowblocks to be freed under dirty pagecache during unshare

 - Update MAINTAINERS file to quote the new maintainer

* tag 'xfs-6.12-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: fix a typo
  xfs: don't free cowblocks from under dirty pagecache on unshare
  xfs: skip background cowblock trims on inodes open for write
  xfs: support lowmode allocations in xfs_bmap_exact_minlen_extent_alloc
  xfs: call xfs_bmap_exact_minlen_extent_alloc from xfs_bmap_btalloc
  xfs: don't ifdef around the exact minlen allocations
  xfs: fold xfs_bmap_alloc_userdata into xfs_bmapi_allocate
  xfs: distinguish extra split from real ENOSPC from xfs_attr_node_try_addname
  xfs: distinguish extra split from real ENOSPC from xfs_attr3_leaf_split
  xfs: return bool from xfs_attr3_leaf_add
  xfs: merge xfs_attr_leaf_try_add into xfs_attr_leaf_addname
  xfs: Use try_cmpxchg() in xlog_cil_insert_pcp_aggregate()
  xfs: scrub: convert comma to semicolon
  xfs: Remove empty declartion in header file
  MAINTAINERS: add Carlos Maiolino as XFS release manager

Simon Horman says:

====================
MAINTAINERS: Networking file coverage updates

The aim of this proposal is to make the handling of some files,
related to Networking and Wireless, more consistently. It does so by:

1. Adding some more headers to the UDP section, making it consistent
   with the TCP section.

2. Excluding some files relating to Wireless from NETWORKING [GENERAL],
   making their handling consistent with other files related to
   Wireless.

The aim of this is to make things more consistent.  And for MAINTAINERS
to better reflect the situation on the ground.  I am more than happy to
be told that the current state of affairs is fine. Or for other ideas to
be discussed.

v1: https://lore.kernel.org/20241004-maint-net-hdrs-v1-0-41fd555aacc5@kernel.org
====================

Link: https://patch.msgid.link/20241009-maint-net-hdrs-v2-0-f2c86e7309c8@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Add netdev mailing list and some more udp.h headers to the UDP section.
This is now more consistent with the TCP section.
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241009-maint-net-hdrs-v2-2-f2c86e7309c8@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

We already exclude wireless drivers from the netdev@ traffic, to
delegate it to linux-wireless@, and avoid overwhelming netdev@.

Many of the following wireless-related sections MAINTAINERS
are already not included in the NETWORKING [GENERAL] section.
For consistency, exclude those that are.

* 802.11 (including CFG80211/NL80211)
* MAC80211
* RFKILL
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241009-maint-net-hdrs-v2-1-f2c86e7309c8@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

syzbot found that slhc_remember() was missing checks against
malicious packets [1].

slhc_remember() only checked the size of the packet was at least 20,
which is not good enough.

We need to make sure the packet includes the IPv4 and TCP header
that are supposed to be carried.

Add iph and th pointers to make the code more readable.

[1]

BUG: KMSAN: uninit-value in slhc_remember+0x2e8/0x7b0 drivers/net/slip/slhc.c:666
  slhc_remember+0x2e8/0x7b0 drivers/net/slip/slhc.c:666
  ppp_receive_nonmp_frame+0xe45/0x35e0 drivers/net/ppp/ppp_generic.c:2455
  ppp_receive_frame drivers/net/ppp/ppp_generic.c:2372 [inline]
  ppp_do_recv+0x65f/0x40d0 drivers/net/ppp/ppp_generic.c:2212
  ppp_input+0x7dc/0xe60 drivers/net/ppp/ppp_generic.c:2327
  pppoe_rcv_core+0x1d3/0x720 drivers/net/ppp/pppoe.c:379
  sk_backlog_rcv+0x13b/0x420 include/net/sock.h:1113
  __release_sock+0x1da/0x330 net/core/sock.c:3072
  release_sock+0x6b/0x250 net/core/sock.c:3626
  pppoe_sendmsg+0x2b8/0xb90 drivers/net/ppp/pppoe.c:903
  sock_sendmsg_nosec net/socket.c:729 [inline]
  __sock_sendmsg+0x30f/0x380 net/socket.c:744
  ____sys_sendmsg+0x903/0xb60 net/socket.c:2602
  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2656
  __sys_sendmmsg+0x3c1/0x960 net/socket.c:2742
  __do_sys_sendmmsg net/socket.c:2771 [inline]
  __se_sys_sendmmsg net/socket.c:2768 [inline]
  __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2768
  x64_sys_call+0xb6e/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:308
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
  slab_post_alloc_hook mm/slub.c:4091 [inline]
  slab_alloc_node mm/slub.c:4134 [inline]
  kmem_cache_alloc_node_noprof+0x6bf/0xb80 mm/slub.c:4186
  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:587
  __alloc_skb+0x363/0x7b0 net/core/skbuff.c:678
  alloc_skb include/linux/skbuff.h:1322 [inline]
  sock_wmalloc+0xfe/0x1a0 net/core/sock.c:2732
  pppoe_sendmsg+0x3a7/0xb90 drivers/net/ppp/pppoe.c:867
  sock_sendmsg_nosec net/socket.c:729 [inline]
  __sock_sendmsg+0x30f/0x380 net/socket.c:744
  ____sys_sendmsg+0x903/0xb60 net/socket.c:2602
  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2656
  __sys_sendmmsg+0x3c1/0x960 net/socket.c:2742
  __do_sys_sendmmsg net/socket.c:2771 [inline]
  __se_sys_sendmmsg net/socket.c:2768 [inline]
  __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2768
  x64_sys_call+0xb6e/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:308
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 5460 Comm: syz.2.33 Not tainted 6.12.0-rc2-syzkaller-00006-g87d6aab2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024

Fixes: b5451d78 ("slip: Move the SLIP drivers")
Reported-by: syzbot+2ada1bc857496353be5a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/670646db.050a0220.3f80e.0027.GAE@google.com/T/#uSigned-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241009091132.2136321-1-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Eric report a panic on IPPROTO_SMC, and give the facts
that when INET_PROTOSW_ICSK was set, icsk->icsk_sync_mss must be set too.

Bug: Unable to handle kernel NULL pointer dereference at virtual address
0000000000000000
Mem abort info:
ESR = 0x0000000086000005
EC = 0x21: IABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=00000001195d1000
[0000000000000000] pgd=0800000109c46003, p4d=0800000109c46003,
pud=0000000000000000
Internal error: Oops: 0000000086000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 UID: 0 PID: 8037 Comm: syz.3.265 Not tainted
6.11.0-rc7-syzkaller-g5f5673607153 #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 08/06/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : 0x0
lr : cipso_v4_sock_setattr+0x2a8/0x3c0 net/ipv4/cipso_ipv4.c:1910
sp : ffff80009b887a90
x29: ffff80009b887aa0 x28: ffff80008db94050 x27: 0000000000000000
x26: 1fffe0001aa6f5b3 x25: dfff800000000000 x24: ffff0000db75da00
x23: 0000000000000000 x22: ffff0000d8b78518 x21: 0000000000000000
x20: ffff0000d537ad80 x19: ffff0000d8b78000 x18: 1fffe000366d79ee
x17: ffff8000800614a8 x16: ffff800080569b84 x15: 0000000000000001
x14: 000000008b336894 x13: 00000000cd96feaa x12: 0000000000000003
x11: 0000000000040000 x10: 00000000000020a3 x9 : 1fffe0001b16f0f1
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000000040 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000002 x1 : 0000000000000000 x0 : ffff0000d8b78000
Call trace:
0x0
netlbl_sock_setattr+0x2e4/0x338 net/netlabel/netlabel_kapi.c:1000
smack_netlbl_add+0xa4/0x154 security/smack/smack_lsm.c:2593
smack_socket_post_create+0xa8/0x14c security/smack/smack_lsm.c:2973
security_socket_post_create+0x94/0xd4 security/security.c:4425
__sock_create+0x4c8/0x884 net/socket.c:1587
sock_create net/socket.c:1622 [inline]
__sys_socket_create net/socket.c:1659 [inline]
__sys_socket+0x134/0x340 net/socket.c:1706
__do_sys_socket net/socket.c:1720 [inline]
__se_sys_socket net/socket.c:1718 [inline]
__arm64_sys_socket+0x7c/0x94 net/socket.c:1718
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Code: ???????? ???????? ???????? ???????? (????????)
---[ end trace 0000000000000000 ]---

This patch add a toy implementation that performs a simple return to
prevent such panic. This is because MSS can be set in sock_create_kern
or smc_setsockopt, similar to how it's done in AF_SMC. However, for
AF_SMC, there is currently no way to synchronize MSS within
__sys_connect_file. This toy implementation lays the groundwork for us
to support such feature for IPPROTO_SMC in the future.

Fixes: d25a92cc ("net/smc: Introduce IPPROTO_SMC")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Link: https://patch.msgid.link/1728456916-67035-1-git-send-email-alibuda@linux.alibaba.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

syzbot reported an issue in ppp_async_encode() [1]

In this case, pppoe_sendmsg() is called with a zero size.
Then ppp_async_encode() is called with an empty skb.

BUG: KMSAN: uninit-value in ppp_async_encode drivers/net/ppp/ppp_async.c:545 [inline]
 BUG: KMSAN: uninit-value in ppp_async_push+0xb4f/0x2660 drivers/net/ppp/ppp_async.c:675
  ppp_async_encode drivers/net/ppp/ppp_async.c:545 [inline]
  ppp_async_push+0xb4f/0x2660 drivers/net/ppp/ppp_async.c:675
  ppp_async_send+0x130/0x1b0 drivers/net/ppp/ppp_async.c:634
  ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2280 [inline]
  ppp_input+0x1f1/0xe60 drivers/net/ppp/ppp_generic.c:2304
  pppoe_rcv_core+0x1d3/0x720 drivers/net/ppp/pppoe.c:379
  sk_backlog_rcv+0x13b/0x420 include/net/sock.h:1113
  __release_sock+0x1da/0x330 net/core/sock.c:3072
  release_sock+0x6b/0x250 net/core/sock.c:3626
  pppoe_sendmsg+0x2b8/0xb90 drivers/net/ppp/pppoe.c:903
  sock_sendmsg_nosec net/socket.c:729 [inline]
  __sock_sendmsg+0x30f/0x380 net/socket.c:744
  ____sys_sendmsg+0x903/0xb60 net/socket.c:2602
  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2656
  __sys_sendmmsg+0x3c1/0x960 net/socket.c:2742
  __do_sys_sendmmsg net/socket.c:2771 [inline]
  __se_sys_sendmmsg net/socket.c:2768 [inline]
  __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2768
  x64_sys_call+0xb6e/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:308
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
  slab_post_alloc_hook mm/slub.c:4092 [inline]
  slab_alloc_node mm/slub.c:4135 [inline]
  kmem_cache_alloc_node_noprof+0x6bf/0xb80 mm/slub.c:4187
  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:587
  __alloc_skb+0x363/0x7b0 net/core/skbuff.c:678
  alloc_skb include/linux/skbuff.h:1322 [inline]
  sock_wmalloc+0xfe/0x1a0 net/core/sock.c:2732
  pppoe_sendmsg+0x3a7/0xb90 drivers/net/ppp/pppoe.c:867
  sock_sendmsg_nosec net/socket.c:729 [inline]
  __sock_sendmsg+0x30f/0x380 net/socket.c:744
  ____sys_sendmsg+0x903/0xb60 net/socket.c:2602
  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2656
  __sys_sendmmsg+0x3c1/0x960 net/socket.c:2742
  __do_sys_sendmmsg net/socket.c:2771 [inline]
  __se_sys_sendmmsg net/socket.c:2768 [inline]
  __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2768
  x64_sys_call+0xb6e/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:308
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 5411 Comm: syz.1.14 Not tainted 6.12.0-rc1-syzkaller-00165-g360c1f1f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+1d121645899e7692f92a@syzkaller.appspotmail.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241009185802.3763282-1-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The purpose of this section is to document what is the current practice
regarding clean-up patches which address checkpatch warnings and similar
problems. I feel there is a value in having this documented so others
can easily refer to it.

Clearly this topic is subjective. And to some extent the current
practice discourages a wider range of patches than is described here.
But I feel it is best to start somewhere, with the most well established
part of the current practice.
Signed-off-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241009-doc-mc-clean-v2-1-e637b665fa81@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Kuniyuki Iwashima says:

====================
rtnetlink: Handle error of rtnl_register_module().

While converting phonet to per-netns RTNL, I found a weird comment

  /* Further rtnl_register_module() cannot fail */

that was true but no longer true after commit addf9b90 ("net:
rtnetlink: use rcu to free rtnl message handlers").

Many callers of rtnl_register_module() just ignore the returned
value but should handle them properly.

This series introduces two helpers, rtnl_register_many() and
rtnl_unregister_many(), to do that easily and fix such callers.

All rtnl_register() and rtnl_register_module() will be converted
to _many() variant and some rtnl_lock() will be saved in _many()
later in net-next.

Changes:
  v4:
    * Add more context in changelog of each patch

  v3: https://lore.kernel.org/all/20241007124459.5727-1-kuniyu@amazon.com/
    * Move module *owner to struct rtnl_msg_handler
    * Make struct rtnl_msg_handler args/vars const
    * Update mctp goto labels

  v2: https://lore.kernel.org/netdev/20241004222358.79129-1-kuniyu@amazon.com/
    * Remove __exit from mctp_neigh_exit().

  v1: https://lore.kernel.org/netdev/20241003205725.5612-1-kuniyu@amazon.com/
====================

Link: https://patch.msgid.link/20241008184737.9619-1-kuniyu@amazon.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Before commit addf9b90 ("net: rtnetlink: use rcu to free rtnl
message handlers"), once the first rtnl_register_module() allocated
rtnl_msg_handlers[PF_PHONET], the following calls never failed.

However, after the commit, rtnl_register_module() could fail silently
to allocate rtnl_msg_handlers[PF_PHONET][msgtype] and requires error
handling for each call.

Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality.  This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.

Let's use rtnl_register_many() to handle the errors easily.

Fixes: addf9b90 ("net: rtnetlink: use rcu to free rtnl message handlers")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Rémi Denis-Courmont <courmisch@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Since introduced, mpls_init() has been ignoring the returned
value of rtnl_register_module(), which could fail silently.

Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality.  This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.

Let's handle the errors by rtnl_register_many().

Fixes: 03c05665 ("mpls: Netlink commands to add, remove, and dump routes")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Since introduced, mctp has been ignoring the returned value of
rtnl_register_module(), which could fail silently.

Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality.  This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.

Let's handle the errors by rtnl_register_many().

Fixes: 583be982 ("mctp: Add device handling and netlink interface")
Fixes: 831119f8 ("mctp: Add neighbour netlink interface")
Fixes: 06d2f4c5 ("mctp: Add netlink route management")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Since introduced, br_vlan_rtnl_init() has been ignoring the returned
value of rtnl_register_module(), which could fail silently.

Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality.  This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.

Let's handle the errors by rtnl_register_many().

Fixes: 8dcea187 ("net: bridge: vlan: add rtm definitions and dump support")
Fixes: f26b2965 ("net: bridge: vlan: add new rtm message support")
Fixes: adb3ce9b ("net: bridge: vlan: add del rtm message support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Since introduced, vxlan_vnifilter_init() has been ignoring the
returned value of rtnl_register_module(), which could fail silently.

Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality.  This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.

Let's handle the errors by rtnl_register_many().

Fixes: f9c4bb0b ("vxlan: vni filtering support on collect metadata device")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Before commit addf9b90 ("net: rtnetlink: use rcu to free rtnl message
handlers"), once rtnl_msg_handlers[protocol] was allocated, the following
rtnl_register_module() for the same protocol never failed.

However, after the commit, rtnl_msg_handler[protocol][msgtype] needs to
be allocated in each rtnl_register_module(), so each call could fail.

Many callers of rtnl_register_module() do not handle the returned error,
and we need to add many error handlings.

To handle that easily, let's add wrapper functions for bulk registration
of rtnetlink message handlers.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) Restrict xtables extensions to families that are safe, syzbot found
   a way to combine ebtables with extensions that are never used by
   userspace tools. From Florian Westphal.

2) Set l3mdev inconditionally whenever possible in nft_fib to fix lookup
   mismatch, also from Florian.

netfilter pull request 24-10-09

* tag 'nf-24-10-09' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  selftests: netfilter: conntrack_vrf.sh: add fib test case
  netfilter: fib: check correct rtable in vrf setups
  netfilter: xtables: avoid NFPROTO_UNSPEC where needed
====================

Link: https://patch.msgid.link/20241009213858.3565808-1-pablo@netfilter.orgSigned-off-by: Paolo Abeni <pabeni@redhat.com>

dst_entries_add() uses per-cpu data that might be freed at netns
dismantle from ip6_route_net_exit() calling dst_entries_destroy()

Before ip6_route_net_exit() can be called, we release all
the dsts associated with this netns, via calls to dst_release(),
which waits an rcu grace period before calling dst_destroy()

dst_entries_add() use in dst_destroy() is racy, because
dst_entries_destroy() could have been called already.

Decrementing the number of dsts must happen sooner.

Notes:

1) in CONFIG_XFRM case, dst_destroy() can call
   dst_release_immediate(child), this might also cause UAF
   if the child does not have DST_NOCOUNT set.
   IPSEC maintainers might take a look and see how to address this.

2) There is also discussion about removing this count of dst,
   which might happen in future kernels.

Fixes: f8864972 ("ipv4: fix dst race in sk_dst_get()")
Closes: https://lore.kernel.org/lkml/CANn89iLCCGsP7SFn9HKpvnKu96Td4KD08xf7aGtiYgZnkjaL=w@mail.gmail.com/T/Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Xin Long <lucien.xin@gmail.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20241008143110.1064899-1-edumazet@google.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Tony Nguyen says:

====================
Intel Wired LAN Driver Updates 2024-10-08 (ice, i40e, igb, e1000e)

This series contains updates to ice, i40e, igb, and e1000e drivers.

For ice:

Marcin allows driver to load, into safe mode, when DDP package is
missing or corrupted and adjusts the netif_is_ice() check to
account for when the device is in safe mode. He also fixes an
out-of-bounds issue when MSI-X are increased for VFs.

Wojciech clears FDB entries on reset to match the hardware state.

For i40e:

Aleksandr adds locking around MACVLAN filters to prevent memory leaks
due to concurrency issues.

For igb:

Mohamed Khalfella adds a check to not attempt to bring up an already
running interface on non-fatal PCIe errors.

For e1000e:

Vitaly changes board type for I219 to more closely match the hardware
and stop PHY issues.

* '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue:
  e1000e: change I219 (19) devices to ADP
  igb: Do not bring the device up after non-fatal error
  i40e: Fix macvlan leak by synchronizing access to mac_filter_hash
  ice: Fix increasing MSI-X on VF
  ice: Flush FDB entries before reset
  ice: Fix netif_is_ice() in Safe Mode
  ice: Fix entering Safe Mode
====================

Link: https://patch.msgid.link/20241008230050.928245-1-anthony.l.nguyen@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Matthieu Baerts says:

====================
mptcp: misc. fixes involving fallback to TCP

- Patch 1: better handle DSS corruptions from a bugged peer: reducing
  warnings, doing a fallback or a reset depending on the subflow state.
  For >= v5.7.

- Patch 2: fix DSS corruption due to large pmtu xmit, where MPTCP was
  not taken into account. For >= v5.6.

- Patch 3: fallback when MPTCP opts are dropped after the first data
  packet, instead of resetting the connection. For >= v5.6.

- Patch 4: restrict the removal of a subflow to other closing states, a
  better fix, for a recent one. For >= v5.10.
====================

Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-0-c6fb8e93e551@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

In a previous fix, the in-kernel path-manager has been modified not to
retrigger the removal of a subflow if it was already closed, e.g. when
the initial subflow is removed, but kept in the subflows list.

To be complete, this fix should also skip the subflows that are in any
closing state: mptcp_close_ssk() will initiate the closure, but the
switch to the TCP_CLOSE state depends on the other peer.

Fixes: 58e1b66b ("mptcp: pm: do not remove already closed subflows")
Cc: stable@vger.kernel.org
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-4-c6fb8e93e551@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

As reported by Christoph [1], before this patch, an MPTCP connection was
wrongly reset when a host received a first data packet with MPTCP
options after the 3wHS, but got the next ones without.

According to the MPTCP v1 specs [2], a fallback should happen in this
case, because the host didn't receive a DATA_ACK from the other peer,
nor receive data for more than the initial window which implies a
DATA_ACK being received by the other peer.

The patch here re-uses the same logic as the one used in other places:
by looking at allow_infinite_fallback, which is disabled at the creation
of an additional subflow. It's not looking at the first DATA_ACK (or
implying one received from the other side) as suggested by the RFC, but
it is in continuation with what was already done, which is safer, and it
fixes the reported issue. The next step, looking at this first DATA_ACK,
is tracked in [4].

This patch has been validated using the following Packetdrill script:

   0 socket(..., SOCK_STREAM, IPPROTO_MPTCP) = 3
  +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
  +0 bind(3, ..., ...) = 0
  +0 listen(3, 1) = 0

  // 3WHS is OK
  +0.0 < S  0:0(0)       win 65535  <mss 1460, sackOK, nop, nop, nop, wscale 6, mpcapable v1 flags[flag_h] nokey>
  +0.0 > S. 0:0(0) ack 1            <mss 1460, nop, nop, sackOK, nop, wscale 8, mpcapable v1 flags[flag_h] key[skey]>
  +0.1 <  . 1:1(0) ack 1 win 2048                                              <mpcapable v1 flags[flag_h] key[ckey=2, skey]>
  +0 accept(3, ..., ...) = 4

  // Data from the client with valid MPTCP options (no DATA_ACK: normal)
  +0.1 < P. 1:501(500) ack 1 win 2048 <mpcapable v1 flags[flag_h] key[skey, ckey] mpcdatalen 500, nop, nop>
  // From here, the MPTCP options will be dropped by a middlebox
  +0.0 >  . 1:1(0)     ack 501        <dss dack8=501 dll=0 nocs>

  +0.1 read(4, ..., 500) = 500
  +0   write(4, ..., 100) = 100

  // The server replies with data, still thinking MPTCP is being used
  +0.0 > P. 1:101(100)   ack 501          <dss dack8=501 dsn8=1 ssn=1 dll=100 nocs, nop, nop>
  // But the client already did a fallback to TCP, because the two previous packets have been received without MPTCP options
  +0.1 <  . 501:501(0)   ack 101 win 2048

  +0.0 < P. 501:601(100) ack 101 win 2048
  // The server should fallback to TCP, not reset: it didn't get a DATA_ACK, nor data for more than the initial window
  +0.0 >  . 101:101(0)   ack 601

Note that this script requires Packetdrill with MPTCP support, see [3].

Fixes: dea2b1ea ("mptcp: do not reset MP_CAPABLE subflow on mapping errors")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/518 [1]
Link: https://datatracker.ietf.org/doc/html/rfc8684#name-fallback [2]
Link: https://github.com/multipath-tcp/packetdrill [3]
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/519 [4]
Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-3-c6fb8e93e551@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Syzkaller was able to trigger a DSS corruption:

  TCP: request_sock_subflow_v4: Possible SYN flooding on port [::]:20002. Sending cookies.
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 5227 at net/mptcp/protocol.c:695 __mptcp_move_skbs_from_subflow+0x20a9/0x21f0 net/mptcp/protocol.c:695
  Modules linked in:
  CPU: 0 UID: 0 PID: 5227 Comm: syz-executor350 Not tainted 6.11.0-syzkaller-08829-gaf9c191a #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
  RIP: 0010:__mptcp_move_skbs_from_subflow+0x20a9/0x21f0 net/mptcp/protocol.c:695
  Code: 0f b6 dc 31 ff 89 de e8 b5 dd ea f5 89 d8 48 81 c4 50 01 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 98 da ea f5 90 <0f> 0b 90 e9 47 ff ff ff e8 8a da ea f5 90 0f 0b 90 e9 99 e0 ff ff
  RSP: 0018:ffffc90000006db8 EFLAGS: 00010246
  RAX: ffffffff8ba9df18 RBX: 00000000000055f0 RCX: ffff888030023c00
  RDX: 0000000000000100 RSI: 00000000000081e5 RDI: 00000000000055f0
  RBP: 1ffff110062bf1ae R08: ffffffff8ba9cf12 R09: 1ffff110062bf1b8
  R10: dffffc0000000000 R11: ffffed10062bf1b9 R12: 0000000000000000
  R13: dffffc0000000000 R14: 00000000700cec61 R15: 00000000000081e5
  FS:  000055556679c380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000020287000 CR3: 0000000077892000 CR4: 00000000003506f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   <IRQ>
   move_skbs_to_msk net/mptcp/protocol.c:811 [inline]
   mptcp_data_ready+0x29c/0xa90 net/mptcp/protocol.c:854
   subflow_data_ready+0x34a/0x920 net/mptcp/subflow.c:1490
   tcp_data_queue+0x20fd/0x76c0 net/ipv4/tcp_input.c:5283
   tcp_rcv_established+0xfba/0x2020 net/ipv4/tcp_input.c:6237
   tcp_v4_do_rcv+0x96d/0xc70 net/ipv4/tcp_ipv4.c:1915
   tcp_v4_rcv+0x2dc0/0x37f0 net/ipv4/tcp_ipv4.c:2350
   ip_protocol_deliver_rcu+0x22e/0x440 net/ipv4/ip_input.c:205
   ip_local_deliver_finish+0x341/0x5f0 net/ipv4/ip_input.c:233
   NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314
   NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314
   __netif_receive_skb_one_core net/core/dev.c:5662 [inline]
   __netif_receive_skb+0x2bf/0x650 net/core/dev.c:5775
   process_backlog+0x662/0x15b0 net/core/dev.c:6107
   __napi_poll+0xcb/0x490 net/core/dev.c:6771
   napi_poll net/core/dev.c:6840 [inline]
   net_rx_action+0x89b/0x1240 net/core/dev.c:6962
   handle_softirqs+0x2c5/0x980 kernel/softirq.c:554
   do_softirq+0x11b/0x1e0 kernel/softirq.c:455
   </IRQ>
   <TASK>
   __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382
   local_bh_enable include/linux/bottom_half.h:33 [inline]
   rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline]
   __dev_queue_xmit+0x1764/0x3e80 net/core/dev.c:4451
   dev_queue_xmit include/linux/netdevice.h:3094 [inline]
   neigh_hh_output include/net/neighbour.h:526 [inline]
   neigh_output include/net/neighbour.h:540 [inline]
   ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:236
   ip_local_out net/ipv4/ip_output.c:130 [inline]
   __ip_queue_xmit+0x118c/0x1b80 net/ipv4/ip_output.c:536
   __tcp_transmit_skb+0x2544/0x3b30 net/ipv4/tcp_output.c:1466
   tcp_transmit_skb net/ipv4/tcp_output.c:1484 [inline]
   tcp_mtu_probe net/ipv4/tcp_output.c:2547 [inline]
   tcp_write_xmit+0x641d/0x6bf0 net/ipv4/tcp_output.c:2752
   __tcp_push_pending_frames+0x9b/0x360 net/ipv4/tcp_output.c:3015
   tcp_push_pending_frames include/net/tcp.h:2107 [inline]
   tcp_data_snd_check net/ipv4/tcp_input.c:5714 [inline]
   tcp_rcv_established+0x1026/0x2020 net/ipv4/tcp_input.c:6239
   tcp_v4_do_rcv+0x96d/0xc70 net/ipv4/tcp_ipv4.c:1915
   sk_backlog_rcv include/net/sock.h:1113 [inline]
   __release_sock+0x214/0x350 net/core/sock.c:3072
   release_sock+0x61/0x1f0 net/core/sock.c:3626
   mptcp_push_release net/mptcp/protocol.c:1486 [inline]
   __mptcp_push_pending+0x6b5/0x9f0 net/mptcp/protocol.c:1625
   mptcp_sendmsg+0x10bb/0x1b10 net/mptcp/protocol.c:1903
   sock_sendmsg_nosec net/socket.c:730 [inline]
   __sock_sendmsg+0x1a6/0x270 net/socket.c:745
   ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2603
   ___sys_sendmsg net/socket.c:2657 [inline]
   __sys_sendmsg+0x2aa/0x390 net/socket.c:2686
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x7fb06e9317f9
  Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
  RSP: 002b:00007ffe2cfd4f98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
  RAX: ffffffffffffffda RBX: 00007fb06e97f468 RCX: 00007fb06e9317f9
  RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000005
  RBP: 00007fb06e97f446 R08: 0000555500000000 R09: 0000555500000000
  R10: 0000555500000000 R11: 0000000000000246 R12: 00007fb06e97f406
  R13: 0000000000000001 R14: 00007ffe2cfd4fe0 R15: 0000000000000003
   </TASK>

Additionally syzkaller provided a nice reproducer. The repro enables
pmtu on the loopback device, leading to tcp_mtu_probe() generating
very large probe packets.

tcp_can_coalesce_send_queue_head() currently does not check for
mptcp-level invariants, and allowed the creation of cross-DSS probes,
leading to the mentioned corruption.

Address the issue teaching tcp_can_coalesce_send_queue_head() about
mptcp using the tcp_skb_can_collapse(), also reducing the code
duplication.

Fixes: 85712484 ("tcp: coalesce/collapse must respect MPTCP extensions")
Cc: stable@vger.kernel.org
Reported-by: syzbot+d1bff73460e33101f0e7@syzkaller.appspotmail.com
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/513Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-2-c6fb8e93e551@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Bugged peer implementation can send corrupted DSS options, consistently
hitting a few warning in the data path. Use DEBUG_NET assertions, to
avoid the splat on some builds and handle consistently the error, dumping
related MIBs and performing fallback and/or reset according to the
subflow type.

Fixes: 6771bfd9 ("mptcp: update mptcp ack sequence from work queue")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-1-c6fb8e93e551@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

A warning is triggered when there is insufficient space in the buffer
for userdata. However, this is not an issue since userdata will be sent
in the next iteration.

Current warning message:

    ------------[ cut here ]------------
     WARNING: CPU: 13 PID: 3013042 at drivers/net/netconsole.c:1122 write_ext_msg+0x3b6/0x3d0
      ? write_ext_msg+0x3b6/0x3d0
      console_flush_all+0x1e9/0x330

The code incorrectly issues a warning when this_chunk is zero, which is
a valid scenario. The warning should only be triggered when this_chunk
is negative.

Fixes: 1ec9daf9 ("net: netconsole: append userdata to fragmented netconsole messages")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241008094325.896208-1-leitao@debian.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

In case of a tc mirred action from one switch to another, the behavior
is not correct. We simply tell the source switch driver to program a
mirroring entry towards mirror->to_local_port = to_dp->index, but it is
not even guaranteed that the to_dp belongs to the same switch as dp.

For proper cross-chip support, we would need to go through the
cross-chip notifier layer in switch.c, program the entry on cascade
ports, and introduce new, explicit API for cross-chip mirroring, given
that intermediary switches should have introspection into the DSA tags
passed through the cascade port (and not just program a port mirror on
the entire cascade port). None of that exists today.

Reject what is not implemented so that user space is not misled into
thinking it works.

Fixes: f50f2127 ("net: dsa: Add plumbing for port mirroring")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20241008094320.3340980-1-vladimir.oltean@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Some platforms (such as i.MX25 and i.MX27) do not support PTP, so on
these platforms fec_ptp_init() is not called and the related members
in fep are not initialized. However, fec_ptp_save_state() is called
unconditionally, which causes the kernel to panic. Therefore, add a
condition so that fec_ptp_save_state() is not called if PTP is not
supported.

Fixes: a1477dc8 ("net: fec: Restart PPS after link state change")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/lkml/353e41fe-6bb4-4ee9-9980-2da2a9c1c508@roeck-us.net/Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Csókás, Bence <csokas.bence@prolan.hu>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://patch.msgid.link/20241008061153.1977930-1-wei.fang@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

It's done in probe so it should be undone here.

Fixes: 1d3bb996 ("Device tree aware EMAC driver")
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20241008233050.9422-1-rosenp@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>