of_find_node_by_name() will do an of_node_put() on the "from" argument.
With CONFIG_OF_DYNAMIC enabled which checks for device_node reference
counts, we would be getting a warning like this:

[    6.347230] refcount_t: increment on 0; use-after-free.
[    6.352498] WARNING: CPU: 3 PID: 77 at lib/refcount.c:156
refcount_inc_checked+0x38/0x44
[    6.360601] Modules linked in:
[    6.363661] CPU: 3 PID: 77 Comm: kworker/3:1 Tainted: G        W
5.4.46-gb78b3e9956e6 #13
[    6.372546] Hardware name: BCM97278SV (DT)
[    6.376649] Workqueue: events deferred_probe_work_func
[    6.381796] pstate: 60000005 (nZCv daif -PAN -UAO)
[    6.386595] pc : refcount_inc_checked+0x38/0x44
[    6.391133] lr : refcount_inc_checked+0x38/0x44
...
[    6.478791] Call trace:
[    6.481243]  refcount_inc_checked+0x38/0x44
[    6.485433]  kobject_get+0x3c/0x4c
[    6.488840]  of_node_get+0x24/0x34
[    6.492247]  of_irq_find_parent+0x3c/0xe0
[    6.496263]  of_irq_parse_one+0xe4/0x1d0
[    6.500191]  irq_of_parse_and_map+0x44/0x84
[    6.504381]  bcm_sf2_sw_probe+0x22c/0x844
[    6.508397]  platform_drv_probe+0x58/0xa8
[    6.512413]  really_probe+0x238/0x3fc
[    6.516081]  driver_probe_device+0x11c/0x12c
[    6.520358]  __device_attach_driver+0xa8/0x100
[    6.524808]  bus_for_each_drv+0xb4/0xd0
[    6.528650]  __device_attach+0xd0/0x164
[    6.532493]  device_initial_probe+0x24/0x30
[    6.536682]  bus_probe_device+0x38/0x98
[    6.540524]  deferred_probe_work_func+0xa8/0xd4
[    6.545061]  process_one_work+0x178/0x288
[    6.549078]  process_scheduled_works+0x44/0x48
[    6.553529]  worker_thread+0x218/0x270
[    6.557285]  kthread+0xdc/0xe4
[    6.560344]  ret_from_fork+0x10/0x18
[    6.563925] ---[ end trace 68f65caf69bb152a ]---

Fix this by adding a of_node_get() to increment the reference count
prior to the call.

Fixes: afa3b592 ("net: dsa: bcm_sf2: Ensure correct sub-node is parsed")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit 3b335832 ("net: Add fraglist GRO/GSO feature flags") missed
an entry for NETIF_F_GSO_FRAGLIST in netdev_features_strings array. As
a result, fraglist GSO feature is not shown in 'ethtool -k' output and
can't be toggled on/off.
The fix is trivial.

Fixes: 3b335832 ("net: Add fraglist GRO/GSO feature flags")
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

The driver function tg3_io_error_detected() calls napi_disable twice,
without an intervening napi_enable, when the number of EEH errors exceeds
eeh_max_freezes, resulting in an indefinite sleep while holding rtnl_lock.

Add check for pcierr_recovery which skips code already executed for the
"Frozen" state.
Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Code to handle multiproto configuration is missing.

Fixes: 4b5f6723 ("net: Special handling for IP & MPLS")
Signed-off-by: Martin <martin.varghese@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Julian Wiedmann says:

====================
s390/qeth: fixes 2020-06-17

please apply the following patch series for qeth to netdev's net tree.

The first patch fixes a regression in the error handling for a specific
cmd type. I have some follow-ups queued up for net-next to clean this
up properly...

The second patch fine-tunes the HW offload restrictions that went in
with this merge window. In some setups we don't need to apply them.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

When a device is configured with ISOLATION_MODE_FWD, traffic never goes
through the internal switch. Don't apply the offload restrictions in
this case.

Fixes: c619e9a6 ("s390/qeth: don't use restricted offloads for local traffic")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Current(?) OSA devices also store their cmd-specific return codes for
SET_ACCESS_CONTROL cmds into the top-level cmd->hdr.return_code.
So once we added stricter checking for the top-level field a while ago,
none of the error logic that rolls back the user's configuration to its
old state is applied any longer.

For this specific cmd, go back to the old model where we peek into the
cmd structure even though the top-level field indicated an error.

Fixes: 686c97ee ("s390/qeth: fix error handling in adapter command callbacks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Paolo Abeni says:

====================
mptcp: cope with syncookie on MP_JOINs

Currently syncookies on MP_JOIN connections are not handled correctly: the
connections fallback to TCP and are kept alive instead of resetting them at
fallback time.

The first patch propagates the required information up to syn_recv_sock time,
and the 2nd patch addresses the unifying the error path for all MP_JOIN
requests.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently any MPTCP socket using syn cookies will fallback to
TCP at 3rd ack time. In case of MP_JOIN requests, the RFC mandate
closing the child and sockets, but the existing error paths
do not handle the syncookie scenario correctly.

Address the issue always forcing the child shutdown in case of
MP_JOIN fallback.

Fixes: ae2dd716 ("mptcp: handle tcp fallback when using syn cookies")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The msk ownership is transferred to the child socket at
3rd ack time, so that we avoid more lookups later. If the
request does not reach the 3rd ack, the MSK reference is
dropped at request sock release time.

As a side effect, fallback is now tracked by a NULL msk
reference instead of zeroed 'mp_join' field. This will
simplify the next patch.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ie.,
$ ifconfig eth0 6.6.6.6 netmask 255.255.255.0

$ ip rule add from 6.6.6.6 table 6666

$ ip route add 9.9.9.9 via 6.6.6.6

$ ping -I 6.6.6.6 9.9.9.9
PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.

3 packets transmitted, 0 received, 100% packet loss, time 2079ms

$ arp
Address     HWtype  HWaddress           Flags Mask            Iface
6.6.6.6             (incomplete)                              eth0

The arp request address is error, this is because fib_table_lookup in
fib_check_nh lookup the destnation 9.9.9.9 nexthop, the scope of
the fib result is RT_SCOPE_LINK,the correct scope is RT_SCOPE_HOST.
Here I add a check of whether this is RT_TABLE_MAIN to solve this problem.

Fixes: 3bfd8472 ("net: Use passed in table for nexthop lookups")
Signed-off-by: guodeqing <geffrey.guo@huawei.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Vladimir Oltean says:

====================
Fix VLAN checks for SJA1105 DSA tc-flower filters

This fixes a ridiculous situation where the driver, in VLAN-unaware
mode, would refuse accepting any tc filter:

tc filter replace dev sw1p3 ingress flower skip_sw \
	dst_mac 42:be:24:9b:76:20 \
	action gate (...)
Error: sja1105: Can only gate based on {DMAC, VID, PCP}.

tc filter replace dev sw1p3 ingress protocol 802.1Q flower skip_sw \
	vlan_id 1 vlan_prio 0 dst_mac 42:be:24:9b:76:20 \
	action gate (...)
Error: sja1105: Can only gate based on DMAC.

So, without changing the VLAN awareness state, it says it doesn't want
VLAN-aware rules, and it doesn't want VLAN-unaware rules either. One
would say it's in Schrodinger's state...

Now, the situation has been made worse by commit 7f14937f ("net:
dsa: sja1105: keep the VLAN awareness state in a driver variable"),
which made VLAN awareness a ternary attribute, but after inspecting the
code from before that patch with a truth table, it looks like the
logical bug was there even before.

While attempting to fix this, I also noticed some leftover debugging
code in one of the places that needed to be fixed. It would have
appeared in the context of patch 3/3 anyway, so I decided to create a
patch that removes it.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

This action requires the VLAN awareness state of the switch to be of the
same type as the key that's being added:

- If the switch is unaware of VLAN, then the tc filter key must only
  contain the destination MAC address.
- If the switch is VLAN-aware, the key must also contain the VLAN ID and
  PCP.

But this check doesn't work unless we verify the VLAN awareness state on
both the "if" and the "else" branches.

Fixes: 834f8933 ("net: dsa: sja1105: implement tc-gate using time-triggered virtual links")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This action requires the VLAN awareness state of the switch to be of the
same type as the key that's being added:

- If the switch is unaware of VLAN, then the tc filter key must only
  contain the destination MAC address.
- If the switch is VLAN-aware, the key must also contain the VLAN ID and
  PCP.

But this check doesn't work unless we verify the VLAN awareness state on
both the "if" and the "else" branches.

Fixes: dfacc5a2 ("net: dsa: sja1105: support flow-based redirection via virtual links")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This shouldn't be there.

Fixes: 834f8933 ("net: dsa: sja1105: implement tc-gate using time-triggered virtual links")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Davide Caratti says:

====================
two fixes for 'act_gate' control plane

- patch 1/2 attempts to fix the error path of tcf_gate_init() when users
  try to configure 'act_gate' rules with wrong parameters
- patch 2/2 is a follow-up of a recent fix for NULL dereference in
  the error path of tcf_gate_init()

further work will introduce a tdc test for 'act_gate'.

changes since v2:
  - fix undefined behavior in patch 1/2
  - improve comment in patch 2/2
changes since v1:
  coding style fixes in patch 1/2 and 2/2
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

assigning a dummy value of 'clock_id' to avoid cancellation of the cycle
timer before its initialization was a temporary solution, and we still
need to handle the case where act_gate timer parameters are changed by
commands like the following one:

 # tc action replace action gate <parameters>

the fix consists in the following items:

1) remove the workaround assignment of 'clock_id', and init the list of
   entries before the first error path after IDR atomic check/allocation
2) validate 'clock_id' earlier: there is no need to do IDR atomic
   check/allocation if we know that 'clock_id' is a bad value
3) use a dedicated function, 'gate_setup_timer()', to ensure that the
   timer is cancelled and re-initialized on action overwrite, and also
   ensure we initialize the timer in the error path of tcf_gate_init()

v3: improve comment in the error path of tcf_gate_init() (thanks to
    Vladimir Oltean)
v2: avoid 'goto' in gate_setup_timer (thanks to Cong Wang)

CC: Ivan Vecera <ivecera@redhat.com>
Fixes: a01c2454 ("net/sched: fix a couple of splats in the error path of tfc_gate_init()")
Fixes: a51c328d ("net: qos: introduce a gate control flow action")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

it is possible to see a KASAN use-after-free, immediately followed by a
NULL dereference crash, with the following command:

 # tc action add action gate index 3 cycle-time 100000000ns \
 > cycle-time-ext 100000000ns clockid CLOCK_TAI

 BUG: KASAN: use-after-free in tcf_action_init_1+0x8eb/0x960
 Write of size 1 at addr ffff88810a5908bc by task tc/883

 CPU: 0 PID: 883 Comm: tc Not tainted 5.7.0+ #188
 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014
 Call Trace:
  dump_stack+0x75/0xa0
  print_address_description.constprop.6+0x1a/0x220
  kasan_report.cold.9+0x37/0x7c
  tcf_action_init_1+0x8eb/0x960
  tcf_action_init+0x157/0x2a0
  tcf_action_add+0xd9/0x2f0
  tc_ctl_action+0x2a3/0x39d
  rtnetlink_rcv_msg+0x5f3/0x920
  netlink_rcv_skb+0x120/0x380
  netlink_unicast+0x439/0x630
  netlink_sendmsg+0x714/0xbf0
  sock_sendmsg+0xe2/0x110
  ____sys_sendmsg+0x5b4/0x890
  ___sys_sendmsg+0xe9/0x160
  __sys_sendmsg+0xd3/0x170
  do_syscall_64+0x9a/0x370
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[...]

 KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077]
 CPU: 0 PID: 883 Comm: tc Tainted: G    B             5.7.0+ #188
 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014
 RIP: 0010:tcf_action_fill_size+0xa3/0xf0
 [....]
 RSP: 0018:ffff88813a48f250 EFLAGS: 00010212
 RAX: dffffc0000000000 RBX: 0000000000000094 RCX: ffffffffa47c3eb6
 RDX: 000000000000000e RSI: 0000000000000008 RDI: 0000000000000070
 RBP: ffff88810a590800 R08: 0000000000000004 R09: ffffed1027491e03
 R10: 0000000000000003 R11: ffffed1027491e03 R12: 0000000000000000
 R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88810a590800
 FS:  00007f62cae8ce40(0000) GS:ffff888147c00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f62c9d20a10 CR3: 000000013a52a000 CR4: 0000000000340ef0
 Call Trace:
  tcf_action_init+0x172/0x2a0
  tcf_action_add+0xd9/0x2f0
  tc_ctl_action+0x2a3/0x39d
  rtnetlink_rcv_msg+0x5f3/0x920
  netlink_rcv_skb+0x120/0x380
  netlink_unicast+0x439/0x630
  netlink_sendmsg+0x714/0xbf0
  sock_sendmsg+0xe2/0x110
  ____sys_sendmsg+0x5b4/0x890
  ___sys_sendmsg+0xe9/0x160
  __sys_sendmsg+0xd3/0x170
  do_syscall_64+0x9a/0x370
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

this is caused by the test on 'cycletime_ext', that is still unassigned
when the action is newly created. This makes the action .init() return 0
without calling tcf_idr_insert(), hence the UAF + crash.

rework the logic that prevents zero values of cycle-time, as follows:

1) 'tcfg_cycletime_ext' seems to be unused in the action software path,
   and it was already possible by other means to obtain non-zero
   cycletime and zero cycletime-ext. So, removing that test should not
   cause any damage.
2) while at it, we must prevent overwriting configuration data with wrong
   ones: use a temporary variable for 'tcfg_cycletime', and validate it
   preserving the original semantic (that allowed computing the cycle
   time as the sum of all intervals, when not specified by
   TCA_GATE_CYCLE_TIME).
3) remove the test on 'tcfg_cycletime', no more useful, and avoid
   returning -EFAULT, which did not seem an appropriate return value for
   a wrong netlink attribute.

v3: fix uninitialized 'cycletime' (thanks to Vladimir Oltean)
v2: remove useless 'return;' at the end of void gate_get_start_time()

Fixes: a51c328d ("net: qos: introduce a gate control flow action")
CC: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In the datapath, the ip_tunnel_lookup() is used and it internally uses
fallback tunnel device pointer, which is fb_tunnel_dev.
This pointer variable should be set to NULL when a fb interface is deleted.
But there is no routine to set fb_tunnel_dev pointer to NULL.
So, this pointer will be still used after interface is deleted and
it eventually results in the use-after-free problem.

Test commands:
    ip netns add A
    ip netns add B
    ip link add eth0 type veth peer name eth1
    ip link set eth0 netns A
    ip link set eth1 netns B

    ip netns exec A ip link set lo up
    ip netns exec A ip link set eth0 up
    ip netns exec A ip link add gre1 type gre local 10.0.0.1 \
	    remote 10.0.0.2
    ip netns exec A ip link set gre1 up
    ip netns exec A ip a a 10.0.100.1/24 dev gre1
    ip netns exec A ip a a 10.0.0.1/24 dev eth0

    ip netns exec B ip link set lo up
    ip netns exec B ip link set eth1 up
    ip netns exec B ip link add gre1 type gre local 10.0.0.2 \
	    remote 10.0.0.1
    ip netns exec B ip link set gre1 up
    ip netns exec B ip a a 10.0.100.2/24 dev gre1
    ip netns exec B ip a a 10.0.0.2/24 dev eth1
    ip netns exec A hping3 10.0.100.2 -2 --flood -d 60000 &
    ip netns del B

Splat looks like:
[   77.793450][    C3] ==================================================================
[   77.794702][    C3] BUG: KASAN: use-after-free in ip_tunnel_lookup+0xcc4/0xf30
[   77.795573][    C3] Read of size 4 at addr ffff888060bd9c84 by task hping3/2905
[   77.796398][    C3]
[   77.796664][    C3] CPU: 3 PID: 2905 Comm: hping3 Not tainted 5.8.0-rc1+ #616
[   77.797474][    C3] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[   77.798453][    C3] Call Trace:
[   77.798815][    C3]  <IRQ>
[   77.799142][    C3]  dump_stack+0x9d/0xdb
[   77.799605][    C3]  print_address_description.constprop.7+0x2cc/0x450
[   77.800365][    C3]  ? ip_tunnel_lookup+0xcc4/0xf30
[   77.800908][    C3]  ? ip_tunnel_lookup+0xcc4/0xf30
[   77.801517][    C3]  ? ip_tunnel_lookup+0xcc4/0xf30
[   77.802145][    C3]  kasan_report+0x154/0x190
[   77.802821][    C3]  ? ip_tunnel_lookup+0xcc4/0xf30
[   77.803503][    C3]  ip_tunnel_lookup+0xcc4/0xf30
[   77.804165][    C3]  __ipgre_rcv+0x1ab/0xaa0 [ip_gre]
[   77.804862][    C3]  ? rcu_read_lock_sched_held+0xc0/0xc0
[   77.805621][    C3]  gre_rcv+0x304/0x1910 [ip_gre]
[   77.806293][    C3]  ? lock_acquire+0x1a9/0x870
[   77.806925][    C3]  ? gre_rcv+0xfe/0x354 [gre]
[   77.807559][    C3]  ? erspan_xmit+0x2e60/0x2e60 [ip_gre]
[   77.808305][    C3]  ? rcu_read_lock_sched_held+0xc0/0xc0
[   77.809032][    C3]  ? rcu_read_lock_held+0x90/0xa0
[   77.809713][    C3]  gre_rcv+0x1b8/0x354 [gre]
[ ... ]
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: c5441932 ("GRE: Refactor GRE tunneling code.")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In the datapath, the ip6gre_tunnel_lookup() is used and it internally uses
fallback tunnel device pointer, which is fb_tunnel_dev.
This pointer variable should be set to NULL when a fb interface is deleted.
But there is no routine to set fb_tunnel_dev pointer to NULL.
So, this pointer will be still used after interface is deleted and
it eventually results in the use-after-free problem.

Test commands:
    ip netns add A
    ip netns add B
    ip link add eth0 type veth peer name eth1
    ip link set eth0 netns A
    ip link set eth1 netns B

    ip netns exec A ip link set lo up
    ip netns exec A ip link set eth0 up
    ip netns exec A ip link add ip6gre1 type ip6gre local fc:0::1 \
	    remote fc:0::2
    ip netns exec A ip -6 a a fc:100::1/64 dev ip6gre1
    ip netns exec A ip link set ip6gre1 up
    ip netns exec A ip -6 a a fc:0::1/64 dev eth0
    ip netns exec A ip link set ip6gre0 up

    ip netns exec B ip link set lo up
    ip netns exec B ip link set eth1 up
    ip netns exec B ip link add ip6gre1 type ip6gre local fc:0::2 \
	    remote fc:0::1
    ip netns exec B ip -6 a a fc:100::2/64 dev ip6gre1
    ip netns exec B ip link set ip6gre1 up
    ip netns exec B ip -6 a a fc:0::2/64 dev eth1
    ip netns exec B ip link set ip6gre0 up
    ip netns exec A ping fc:100::2 -s 60000 &
    ip netns del B

Splat looks like:
[   73.087285][    C1] BUG: KASAN: use-after-free in ip6gre_tunnel_lookup+0x1064/0x13f0 [ip6_gre]
[   73.088361][    C1] Read of size 4 at addr ffff888040559218 by task ping/1429
[   73.089317][    C1]
[   73.089638][    C1] CPU: 1 PID: 1429 Comm: ping Not tainted 5.7.0+ #602
[   73.090531][    C1] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[   73.091725][    C1] Call Trace:
[   73.092160][    C1]  <IRQ>
[   73.092556][    C1]  dump_stack+0x96/0xdb
[   73.093122][    C1]  print_address_description.constprop.6+0x2cc/0x450
[   73.094016][    C1]  ? ip6gre_tunnel_lookup+0x1064/0x13f0 [ip6_gre]
[   73.094894][    C1]  ? ip6gre_tunnel_lookup+0x1064/0x13f0 [ip6_gre]
[   73.095767][    C1]  ? ip6gre_tunnel_lookup+0x1064/0x13f0 [ip6_gre]
[   73.096619][    C1]  kasan_report+0x154/0x190
[   73.097209][    C1]  ? ip6gre_tunnel_lookup+0x1064/0x13f0 [ip6_gre]
[   73.097989][    C1]  ip6gre_tunnel_lookup+0x1064/0x13f0 [ip6_gre]
[   73.098750][    C1]  ? gre_del_protocol+0x60/0x60 [gre]
[   73.099500][    C1]  gre_rcv+0x1c5/0x1450 [ip6_gre]
[   73.100199][    C1]  ? ip6gre_header+0xf00/0xf00 [ip6_gre]
[   73.100985][    C1]  ? rcu_read_lock_sched_held+0xc0/0xc0
[   73.101830][    C1]  ? ip6_input_finish+0x5/0xf0
[   73.102483][    C1]  ip6_protocol_deliver_rcu+0xcbb/0x1510
[   73.103296][    C1]  ip6_input_finish+0x5b/0xf0
[   73.103920][    C1]  ip6_input+0xcd/0x2c0
[   73.104473][    C1]  ? ip6_input_finish+0xf0/0xf0
[   73.105115][    C1]  ? rcu_read_lock_held+0x90/0xa0
[   73.105783][    C1]  ? rcu_read_lock_sched_held+0xc0/0xc0
[   73.106548][    C1]  ipv6_rcv+0x1f1/0x300
[ ... ]
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: c12b395a ("gre: Support GRE over IPv6")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In the current code, ->ndo_start_xmit() can be executed recursively only
10 times because of stack memory.
But, in the case of the vxlan, 10 recursion limit value results in
a stack overflow.
In the current code, the nested interface is limited by 8 depth.
There is no critical reason that the recursion limitation value should
be 10.
So, it would be good to be the same value with the limitation value of
nesting interface depth.

Test commands:
    ip link add vxlan10 type vxlan vni 10 dstport 4789 srcport 4789 4789
    ip link set vxlan10 up
    ip a a 192.168.10.1/24 dev vxlan10
    ip n a 192.168.10.2 dev vxlan10 lladdr fc:22:33:44:55:66 nud permanent

    for i in {9..0}
    do
        let A=$i+1
	ip link add vxlan$i type vxlan vni $i dstport 4789 srcport 4789 4789
	ip link set vxlan$i up
	ip a a 192.168.$i.1/24 dev vxlan$i
	ip n a 192.168.$i.2 dev vxlan$i lladdr fc:22:33:44:55:66 nud permanent
	bridge fdb add fc:22:33:44:55:66 dev vxlan$A dst 192.168.$i.2 self
    done
    hping3 192.168.10.2 -2 -d 60000

Splat looks like:
[  103.814237][ T1127] =============================================================================
[  103.871955][ T1127] BUG kmalloc-2k (Tainted: G    B            ): Padding overwritten. 0x00000000897a2e4f-0x000
[  103.873187][ T1127] -----------------------------------------------------------------------------
[  103.873187][ T1127]
[  103.874252][ T1127] INFO: Slab 0x000000005cccc724 objects=5 used=5 fp=0x0000000000000000 flags=0x10000000001020
[  103.881323][ T1127] CPU: 3 PID: 1127 Comm: hping3 Tainted: G    B             5.7.0+ #575
[  103.882131][ T1127] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  103.883006][ T1127] Call Trace:
[  103.883324][ T1127]  dump_stack+0x96/0xdb
[  103.883716][ T1127]  slab_err+0xad/0xd0
[  103.884106][ T1127]  ? _raw_spin_unlock+0x1f/0x30
[  103.884620][ T1127]  ? get_partial_node.isra.78+0x140/0x360
[  103.885214][ T1127]  slab_pad_check.part.53+0xf7/0x160
[  103.885769][ T1127]  ? pskb_expand_head+0x110/0xe10
[  103.886316][ T1127]  check_slab+0x97/0xb0
[  103.886763][ T1127]  alloc_debug_processing+0x84/0x1a0
[  103.887308][ T1127]  ___slab_alloc+0x5a5/0x630
[  103.887765][ T1127]  ? pskb_expand_head+0x110/0xe10
[  103.888265][ T1127]  ? lock_downgrade+0x730/0x730
[  103.888762][ T1127]  ? pskb_expand_head+0x110/0xe10
[  103.889244][ T1127]  ? __slab_alloc+0x3e/0x80
[  103.889675][ T1127]  __slab_alloc+0x3e/0x80
[  103.890108][ T1127]  __kmalloc_node_track_caller+0xc7/0x420
[ ... ]

Fixes: 11a766ce ("net: Increase xmit RECURSION_LIMIT to 10.")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

I got a memleak report when doing some fuzz test:

unreferenced object 0xffff888112584000 (size 13599):
  comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
  hex dump (first 32 bytes):
    74 61 70 30 00 00 00 00 00 00 00 00 00 00 00 00  tap0............
    00 ee d9 19 81 88 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000002f60ba65>] __kmalloc_node+0x309/0x3a0
    [<0000000075b211ec>] kvmalloc_node+0x7f/0xc0
    [<00000000d3a97396>] alloc_netdev_mqs+0x76/0xfc0
    [<00000000609c3655>] __tun_chr_ioctl+0x1456/0x3d70
    [<000000001127ca24>] ksys_ioctl+0xe5/0x130
    [<00000000b7d5e66a>] __x64_sys_ioctl+0x6f/0xb0
    [<00000000e1023498>] do_syscall_64+0x56/0xa0
    [<000000009ec0eb12>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff888111845cc0 (size 8):
  comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
  hex dump (first 8 bytes):
    74 61 70 30 00 88 ff ff                          tap0....
  backtrace:
    [<000000004c159777>] kstrdup+0x35/0x70
    [<00000000d8b496ad>] kstrdup_const+0x3d/0x50
    [<00000000494e884a>] kvasprintf_const+0xf1/0x180
    [<0000000097880a2b>] kobject_set_name_vargs+0x56/0x140
    [<000000008fbdfc7b>] dev_set_name+0xab/0xe0
    [<000000005b99e3b4>] netdev_register_kobject+0xc0/0x390
    [<00000000602704fe>] register_netdevice+0xb61/0x1250
    [<000000002b7ca244>] __tun_chr_ioctl+0x1cd1/0x3d70
    [<000000001127ca24>] ksys_ioctl+0xe5/0x130
    [<00000000b7d5e66a>] __x64_sys_ioctl+0x6f/0xb0
    [<00000000e1023498>] do_syscall_64+0x56/0xa0
    [<000000009ec0eb12>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff88811886d800 (size 512):
  comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
  hex dump (first 32 bytes):
    00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00  .....N..........
    ff ff ff ff ff ff ff ff c0 66 3d a3 ff ff ff ff  .........f=.....
  backtrace:
    [<0000000050315800>] device_add+0x61e/0x1950
    [<0000000021008dfb>] netdev_register_kobject+0x17e/0x390
    [<00000000602704fe>] register_netdevice+0xb61/0x1250
    [<000000002b7ca244>] __tun_chr_ioctl+0x1cd1/0x3d70
    [<000000001127ca24>] ksys_ioctl+0xe5/0x130
    [<00000000b7d5e66a>] __x64_sys_ioctl+0x6f/0xb0
    [<00000000e1023498>] do_syscall_64+0x56/0xa0
    [<000000009ec0eb12>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

If call_netdevice_notifiers() failed, then rollback_registered()
calls netdev_unregister_kobject() which holds the kobject. The
reference cannot be put because the netdev won't be add to todo
list, so it will leads a memleak, we need put the reference to
avoid memleak.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The older SoCs like Armada XP support a 2500BaseX mode in the datasheets
referred to as DR-SGMII (Double rated SGMII) or HS-SGMII (High Speed
SGMII). This is an upclocked 1000BaseX mode, thus
PHY_INTERFACE_MODE_2500BASEX is the appropriate mode define for it.
adding support for it merely means writing the correct magic value into
the MVNETA_SERDES_CFG register.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

The MVNETA_SERDES_CFG register is only available on older SoCs like the
Armada XP. On newer SoCs like the Armada 38x the fields are moved to
comphy. This patch moves the writes to this register next to the comphy
initialization, so that depending on the SoC either comphy or
MVNETA_SERDES_CFG is configured.
With this we no longer write to the MVNETA_SERDES_CFG on SoCs where it
doesn't exist.
Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Set up vlan_features for use by any vlans above us.

Fixes: beead698 ("ionic: Add the basic NDO callbacks for netdev support")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Acked-by: Jonathan Toppins <jtoppins@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If the driver is busy resetting queues after a change in
MTU or queue parameters, don't bother checking the link,
wait until the next watchdog cycle.

Fixes: 987c0871 ("ionic: check for linkup in watchdog")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Acked-by: Jonathan Toppins <jtoppins@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Using a AX88179 device (0b95:1790), I see two bytes of appended data on
every RX packet. For example, this 48-byte ping, using 0xff as a
payload byte:

  04:20:22.528472 IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 2447, seq 1, length 64
	0x0000:  000a cd35 ea50 000a cd35 ea4f 0800 4500
	0x0010:  0054 c116 4000 4001 f63e c0a8 0101 c0a8
	0x0020:  0102 0800 b633 098f 0001 87ea cd5e 0000
	0x0030:  0000 dcf2 0600 0000 0000 ffff ffff ffff
	0x0040:  ffff ffff ffff ffff ffff ffff ffff ffff
	0x0050:  ffff ffff ffff ffff ffff ffff ffff ffff
	0x0060:  ffff 961f

Those last two bytes - 96 1f - aren't part of the original packet.

In the ax88179 RX path, the usbnet rx_fixup function trims a 2-byte
'alignment pseudo header' from the start of the packet, and sets the
length from a per-packet field populated by hardware. It looks like that
length field *includes* the 2-byte header; the current driver assumes
that it's excluded.

This change trims the 2-byte alignment header after we've set the packet
length, so the resulting packet length is correct. While we're moving
the comment around, this also fixes the spelling of 'pseudo'.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Alexei Starovoitov says:

====================
pull-request: bpf 2020-06-17

The following pull-request contains BPF updates for your *net* tree.

We've added 10 non-merge commits during the last 2 day(s) which contain
a total of 14 files changed, 158 insertions(+), 59 deletions(-).

The main changes are:

1) Important fix for bpf_probe_read_kernel_str() return value, from Andrii.

2) [gs]etsockopt fix for large optlen, from Stanislav.

3) devmap allocation fix, from Toke.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Extend existing doc with more details about requiring ctx->optlen = 0
for handling optval > PAGE_SIZE.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200617010416.93086-3-sdf@google.com

We are relying on the fact, that we can pass > sizeof(int) optvals
to the SOL_IP+IP_FREEBIND option (the kernel will take first 4 bytes).
In the BPF program we check that we can only touch PAGE_SIZE bytes,
but the real optlen is PAGE_SIZE * 2. In both cases, we override it to
some predefined value and trim the optlen.

Also, let's modify exiting IP_TOS usecase to test optlen=0 case
where BPF program just bypasses the data as is.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200617010416.93086-2-sdf@google.com

Attaching to these hooks can break iptables because its optval is
usually quite big, or at least bigger than the current PAGE_SIZE limit.
David also mentioned some SCTP options can be big (around 256k).

For such optvals we expose only the first PAGE_SIZE bytes to
the BPF program. BPF program has two options:
1. Set ctx->optlen to 0 to indicate that the BPF's optval
   should be ignored and the kernel should use original userspace
   value.
2. Set ctx->optlen to something that's smaller than the PAGE_SIZE.

v5:
* use ctx->optlen == 0 with trimmed buffer (Alexei Starovoitov)
* update the docs accordingly

v4:
* use temporary buffer to avoid optval == optval_end == NULL;
  this removes the corner case in the verifier that might assume
  non-zero PTR_TO_PACKET/PTR_TO_PACKET_END.

v3:
* don't increase the limit, bypass the argument

v2:
* proper comments formatting (Jakub Kicinski)

Fixes: 0d01da6a ("bpf: implement getsockopt and setsockopt hooks")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Link: https://lore.kernel.org/bpf/20200617010416.93086-1-sdf@google.com

Syzkaller discovered that creating a hash of type devmap_hash with a large
number of entries can hit the memory allocator limit for allocating
contiguous memory regions. There's really no reason to use kmalloc_array()
directly in the devmap code, so just switch it to the existing
bpf_map_area_alloc() function that is used elsewhere.

Fixes: 6f9d451a ("xdp: Add devmap_hash map type for looking up devices by hashed index")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616142829.114173-1-toke@redhat.com

In commit 34cc0b33 we only handled the frame_sz in convert_to_xdp_frame().
This patch will also handle frame_sz in xdp_convert_zc_to_xdp_frame().

Fixes: 34cc0b33 ("xdp: Xdp_frame add member frame_sz and handle in convert_to_xdp_frame")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616103518.2963410-1-liuhangbin@gmail.com

Commit c34a06c5 ("tools/bpftool: Add ringbuf map to a list of known
map types") added the symbolic "ringbuf" name. Document it in the bpftool
map command docs and usage as well.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616113303.8123-1-tklauser@distanz.ch

During recent refactorings, bpf_probe_read_kernel_str() started returning 0 on
success, instead of amount of data successfully read. This majorly breaks
applications relying on bpf_probe_read_kernel_str() and bpf_probe_read_str()
and their results. Fix this by returning actual number of bytes read.

Fixes: 8d92db5c ("bpf: rework the compat kernel probe handling")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616050432.1902042-1-andriin@fb.com

Pull networking fixes from David Miller:

 1) Don't get per-cpu pointer with preemption enabled in nft_set_pipapo,
    fix from Stefano Brivio.

 2) Fix memory leak in ctnetlink, from Pablo Neira Ayuso.

 3) Multiple definitions of MPTCP_PM_MAX_ADDR, from Geliang Tang.

 4) Accidently disabling NAPI in non-error paths of macb_open(), from
    Charles Keepax.

 5) Fix races between alx_stop and alx_remove, from Zekun Shen.

 6) We forget to re-enable SRIOV during resume in bnxt_en driver, from
    Michael Chan.

 7) Fix memory leak in ipv6_mc_destroy_dev(), from Wang Hai.

 8) rxtx stats use wrong index in mvpp2 driver, from Sven Auhagen.

 9) Fix memory leak in mptcp_subflow_create_socket error path, from Wei
    Yongjun.

10) We should not adjust the TCP window advertised when sending dup acks
    in non-SACK mode, because it won't be counted as a dup by the sender
    if the window size changes. From Eric Dumazet.

11) Destroy the right number of queues during remove in mvpp2 driver,
    from Sven Auhagen.

12) Various WOL and PM fixes to e1000 driver, from Chen Yu, Vaibhav
    Gupta, and Arnd Bergmann.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (35 commits)
  e1000e: fix unused-function warning
  e1000: use generic power management
  e1000e: Do not wake up the system via WOL if device wakeup is disabled
  lan743x: add MODULE_DEVICE_TABLE for module loading alias
  mlxsw: spectrum: Adjust headroom buffers for 8x ports
  bareudp: Fixed configuration to avoid having garbage values
  mvpp2: remove module bugfix
  tcp: grow window for OOO packets only for SACK flows
  mptcp: fix memory leak in mptcp_subflow_create_socket()
  netfilter: flowtable: Make nf_flow_table_offload_add/del_cb inline
  net/sched: act_ct: Make tcf_ct_flow_table_restore_skb inline
  net: dsa: sja1105: fix PTP timestamping with large tc-taprio cycles
  mvpp2: ethtool rxtx stats fix
  MAINTAINERS: switch to my private email for Renesas Ethernet drivers
  rocker: fix incorrect error handling in dma_rings_init
  test_objagg: Fix potential memory leak in error handling
  net: ethernet: mtk-star-emac: simplify interrupt handling
  mld: fix memory leak in ipv6_mc_destroy_dev()
  bnxt_en: Return from timer if interface is not in open state.
  bnxt_en: Fix AER reset logic on 57500 chips.
  ...

Pull AFS fixes from David Howells:
 "I've managed to get xfstests kind of working with afs. Here are a set
  of patches that fix most of the bugs found.

  There are a number of primary issues:

   - Incorrect handling of mtime and non-handling of ctime. It might be
     argued, that the latter isn't a bug since the AFS protocol doesn't
     support ctime, but I should probably still update it locally.

   - Shared-write mmap, truncate and writeback bugs. This includes not
     changing i_size under the callback lock, overwriting local i_size
     with the reply from the server after a partial writeback, not
     limiting the writeback from an mmapped page to EOF.

   - Checks for an abort code indicating that the primary vnode in an
     operation was deleted by a third-party are done in the wrong place.

   - Silly rename bugs. This includes an incomplete conversion to the
     new operation handling, duplicate nlink handling, nlink changing
     not being done inside the callback lock and insufficient handling
     of third-party conflicting directory changes.

  And some secondary ones:

   - The UAEOVERFLOW abort code should map to EOVERFLOW not EREMOTEIO.

   - Remove a couple of unused or incompletely used bits.

   - Remove a couple of redundant success checks.

  These seem to fix all the data-corruption bugs found by

	./check -afs -g quick

  along with the obvious silly rename bugs and time bugs.

  There are still some test failures, but they seem to fall into two
  classes: firstly, the authentication/security model is different to
  the standard UNIX model and permission is arbitrated by the server and
  cached locally; and secondly, there are a number of features that AFS
  does not support (such as mknod). But in these cases, the tests
  themselves need to be adapted or skipped.

  Using the in-kernel afs client with xfstests also found a bug in the
  AuriStor AFS server that has been fixed for a future release"

* tag 'afs-fixes-20200616' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  afs: Fix silly rename
  afs: afs_vnode_commit_status() doesn't need to check the RPC error
  afs: Fix use of afs_check_for_remote_deletion()
  afs: Remove afs_operation::abort_code
  afs: Fix yfs_fs_fetch_status() to honour vnode selector
  afs: Remove yfs_fs_fetch_file_status() as it's not used
  afs: Fix the mapping of the UAEOVERFLOW abort code
  afs: Fix truncation issues and mmap writeback size
  afs: Concoct ctimes
  afs: Fix EOF corruption
  afs: afs_write_end() should change i_size under the right lock
  afs: Fix non-setting of mtime when writing into mmap

Remove SH-5 documentation index entries following the removal
of SH-5 source code.

Error: Cannot open file ../arch/sh/mm/tlb-sh5.c
Error: Cannot open file ../arch/sh/mm/tlb-sh5.c
Error: Cannot open file ../arch/sh/include/asm/tlb_64.h
Error: Cannot open file ../arch/sh/include/asm/tlb_64.h

Fixes: 3b69e8b4 ("Merge tag 'sh-for-5.8' of git://git.libc.org/linux-sh")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Rich Felker <dalias@libc.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: ysato@users.sourceforge.jp
Cc: linux-sh@vger.kernel.org
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull flexible-array member conversions from Gustavo A. R. Silva:
 "Replace zero-length arrays with flexible-array members.

  Notice that all of these patches have been baking in linux-next for
  two development cycles now.

  There is a regular need in the kernel to provide a way to declare
  having a dynamically sized set of trailing elements in a structure.
  Kernel code should always use “flexible array members”[1] for these
  cases. The older style of one-element or zero-length arrays should no
  longer be used[2].

  C99 introduced “flexible array members”, which lacks a numeric size
  for the array declaration entirely:

        struct something {
                size_t count;
                struct foo items[];
        };

  This is the way the kernel expects dynamically sized trailing elements
  to be declared. It allows the compiler to generate errors when the
  flexible array does not occur last in the structure, which helps to
  prevent some kind of undefined behavior[3] bugs from being
  inadvertently introduced to the codebase.

  It also allows the compiler to correctly analyze array sizes (via
  sizeof(), CONFIG_FORTIFY_SOURCE, and CONFIG_UBSAN_BOUNDS). For
  instance, there is no mechanism that warns us that the following
  application of the sizeof() operator to a zero-length array always
  results in zero:

        struct something {
                size_t count;
                struct foo items[0];
        };

        struct something *instance;

        instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
        instance->count = count;

        size = sizeof(instance->items) * instance->count;
        memcpy(instance->items, source, size);

  At the last line of code above, size turns out to be zero, when one
  might have thought it represents the total size in bytes of the
  dynamic memory recently allocated for the trailing array items. Here
  are a couple examples of this issue[4][5].

  Instead, flexible array members have incomplete type, and so the
  sizeof() operator may not be applied[6], so any misuse of such
  operators will be immediately noticed at build time.

  The cleanest and least error-prone way to implement this is through
  the use of a flexible array member:

        struct something {
                size_t count;
                struct foo items[];
        };

        struct something *instance;

        instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
        instance->count = count;

        size = sizeof(instance->items[0]) * instance->count;
        memcpy(instance->items, source, size);

  instead"

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
[4] commit f2cd32a4 ("rndis_wlan: Remove logically dead code")
[5] commit ab91c2a8 ("tpm: eventlog: Replace zero-length array with flexible-array member")
[6] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html

* tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (41 commits)
  w1: Replace zero-length array with flexible-array
  tracing/probe: Replace zero-length array with flexible-array
  soc: ti: Replace zero-length array with flexible-array
  tifm: Replace zero-length array with flexible-array
  dmaengine: tegra-apb: Replace zero-length array with flexible-array
  stm class: Replace zero-length array with flexible-array
  Squashfs: Replace zero-length array with flexible-array
  ASoC: SOF: Replace zero-length array with flexible-array
  ima: Replace zero-length array with flexible-array
  sctp: Replace zero-length array with flexible-array
  phy: samsung: Replace zero-length array with flexible-array
  RxRPC: Replace zero-length array with flexible-array
  rapidio: Replace zero-length array with flexible-array
  media: pwc: Replace zero-length array with flexible-array
  firmware: pcdp: Replace zero-length array with flexible-array
  oprofile: Replace zero-length array with flexible-array
  block: Replace zero-length array with flexible-array
  tools/testing/nvdimm: Replace zero-length array with flexible-array
  libata: Replace zero-length array with flexible-array
  kprobes: Replace zero-length array with flexible-array
  ...

The purgatory Makefile removes -fstack-protector options if they were
configured in, but does not currently add -fno-stack-protector.

If gcc was configured with the --enable-default-ssp configure option,
this results in the stack protector still being enabled for the
purgatory (absent distro-specific specs files that might disable it
again for freestanding compilations), if the main kernel is being
compiled with stack protection enabled (if it's disabled for the main
kernel, the top-level Makefile will add -fno-stack-protector).

This will break the build since commit
  e4160b2e ("x86/purgatory: Fail the build if purgatory.ro has missing symbols")
and prior to that would have caused runtime failure when trying to use
kexec.

Explicitly add -fno-stack-protector to avoid this, as done in other
Makefiles that need to disable the stack protector.
Reported-by: Gabriel C <nix.or.die@googlemail.com>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>