1. 13 Nov, 2014 5 commits
    • Lars-Peter Clausen's avatar
      staging:iio:ad5933: Fix NULL pointer deref when enabling buffer · e72b6917
      Lars-Peter Clausen authored
      commit 824269c5 upstream.
      
      In older versions of the IIO framework it was possible to pass a
      completely different set of channels to iio_buffer_register() as the one
      that is assigned to the IIO device. Commit 959d2952 ("staging:iio: make
      iio_sw_buffer_preenable much more general.") introduced a restriction that
      requires that the set of channels that is passed to iio_buffer_register() is
      a subset of the channels assigned to the IIO device as the IIO core will use
      the list of channels that is assigned to the device to lookup a channel by
      scan index in iio_compute_scan_bytes(). If it can not find the channel the
      function will crash. This patch fixes the issue by making sure that the same
      set of channels is assigned to the IIO device and passed to
      iio_buffer_register().
      
      Fixes the follow NULL pointer derefernce kernel crash:
      	Unable to handle kernel NULL pointer dereference at virtual address 00000016
      	pgd = d53d0000
      	[00000016] *pgd=1534e831, *pte=00000000, *ppte=00000000
      	Internal error: Oops: 17 [#1] PREEMPT SMP ARM
      	Modules linked in:
      	CPU: 1 PID: 1626 Comm: bash Not tainted 3.15.0-19969-g2a180eb-dirty #9545
      	task: d6c124c0 ti: d539a000 task.ti: d539a000
      	PC is at iio_compute_scan_bytes+0x34/0xa8
      	LR is at iio_compute_scan_bytes+0x34/0xa8
      	pc : [<c03052e4>]    lr : [<c03052e4>]    psr: 60070013
      	sp : d539beb8  ip : 00000001  fp : 00000000
      	r10: 00000002  r9 : 00000000  r8 : 00000001
      	r7 : 00000000  r6 : d6dc8800  r5 : d7571000  r4 : 00000002
      	r3 : d7571000  r2 : 00000044  r1 : 00000001  r0 : 00000000
      	Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
      	Control: 18c5387d  Table: 153d004a  DAC: 00000015
      	Process bash (pid: 1626, stack limit = 0xd539a240)
      	Stack: (0xd539beb8 to 0xd539c000)
      	bea0:                                                       c02fc0e4 d7571000
      	bec0: d76c1640 d6dc8800 d757117c 00000000 d757112c c0305b04 d76c1690 d76c1640
      	bee0: d7571188 00000002 00000000 d7571000 d539a000 00000000 000dd1c8 c0305d54
      	bf00: d7571010 0160b868 00000002 c69d3900 d7573278 d7573308 c69d3900 c01ece90
      	bf20: 00000002 c0103fac c0103f6c d539bf88 00000002 c69d3b00 c69d3b0c c0103468
      	bf40: 00000000 00000000 d7694a00 00000002 000af408 d539bf88 c000dd84 c00b2f94
      	bf60: d7694a00 000af408 00000002 d7694a00 d7694a00 00000002 000af408 c000dd84
      	bf80: 00000000 c00b32d0 00000000 00000000 00000002 b6f1aa78 00000002 000af408
      	bfa0: 00000004 c000dc00 b6f1aa78 00000002 00000001 000af408 00000002 00000000
      	bfc0: b6f1aa78 00000002 000af408 00000004 be806a4c 000a6094 00000000 000dd1c8
      	bfe0: 00000000 be8069cc b6e8ab77 b6ec125c 40070010 00000001 22940489 154a5007
      	[<c03052e4>] (iio_compute_scan_bytes) from [<c0305b04>] (__iio_update_buffers+0x248/0x438)
      	[<c0305b04>] (__iio_update_buffers) from [<c0305d54>] (iio_buffer_store_enable+0x60/0x7c)
      	[<c0305d54>] (iio_buffer_store_enable) from [<c01ece90>] (dev_attr_store+0x18/0x24)
      	[<c01ece90>] (dev_attr_store) from [<c0103fac>] (sysfs_kf_write+0x40/0x4c)
      	[<c0103fac>] (sysfs_kf_write) from [<c0103468>] (kernfs_fop_write+0x110/0x154)
      	[<c0103468>] (kernfs_fop_write) from [<c00b2f94>] (vfs_write+0xd0/0x160)
      	[<c00b2f94>] (vfs_write) from [<c00b32d0>] (SyS_write+0x40/0x78)
      	[<c00b32d0>] (SyS_write) from [<c000dc00>] (ret_fast_syscall+0x0/0x30)
      	Code: ea00000e e1a01008 e1a00005 ebfff6fc (e5d0a016)
      
      Fixes: 959d2952 ("staging:iio: make iio_sw_buffer_preenable much more general.")
      Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
      Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      e72b6917
    • Daniel Borkmann's avatar
      net: sctp: fix remote memory pressure from excessive queueing · 565d3c2b
      Daniel Borkmann authored
      commit 26b87c78 upstream.
      
      This scenario is not limited to ASCONF, just taken as one
      example triggering the issue. When receiving ASCONF probes
      in the form of ...
      
        -------------- INIT[ASCONF; ASCONF_ACK] ------------->
        <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
        -------------------- COOKIE-ECHO -------------------->
        <-------------------- COOKIE-ACK ---------------------
        ---- ASCONF_a; [ASCONF_b; ...; ASCONF_n;] JUNK ------>
        [...]
        ---- ASCONF_m; [ASCONF_o; ...; ASCONF_z;] JUNK ------>
      
      ... where ASCONF_a, ASCONF_b, ..., ASCONF_z are good-formed
      ASCONFs and have increasing serial numbers, we process such
      ASCONF chunk(s) marked with !end_of_packet and !singleton,
      since we have not yet reached the SCTP packet end. SCTP does
      only do verification on a chunk by chunk basis, as an SCTP
      packet is nothing more than just a container of a stream of
      chunks which it eats up one by one.
      
      We could run into the case that we receive a packet with a
      malformed tail, above marked as trailing JUNK. All previous
      chunks are here goodformed, so the stack will eat up all
      previous chunks up to this point. In case JUNK does not fit
      into a chunk header and there are no more other chunks in
      the input queue, or in case JUNK contains a garbage chunk
      header, but the encoded chunk length would exceed the skb
      tail, or we came here from an entirely different scenario
      and the chunk has pdiscard=1 mark (without having had a flush
      point), it will happen, that we will excessively queue up
      the association's output queue (a correct final chunk may
      then turn it into a response flood when flushing the
      queue ;)): I ran a simple script with incremental ASCONF
      serial numbers and could see the server side consuming
      excessive amount of RAM [before/after: up to 2GB and more].
      
      The issue at heart is that the chunk train basically ends
      with !end_of_packet and !singleton markers and since commit
      2e3216cd ("sctp: Follow security requirement of responding
      with 1 packet") therefore preventing an output queue flush
      point in sctp_do_sm() -> sctp_cmd_interpreter() on the input
      chunk (chunk = event_arg) even though local_cork is set,
      but its precedence has changed since then. In the normal
      case, the last chunk with end_of_packet=1 would trigger the
      queue flush to accommodate possible outgoing bundling.
      
      In the input queue, sctp_inq_pop() seems to do the right thing
      in terms of discarding invalid chunks. So, above JUNK will
      not enter the state machine and instead be released and exit
      the sctp_assoc_bh_rcv() chunk processing loop. It's simply
      the flush point being missing at loop exit. Adding a try-flush
      approach on the output queue might not work as the underlying
      infrastructure might be long gone at this point due to the
      side-effect interpreter run.
      
      One possibility, albeit a bit of a kludge, would be to defer
      invalid chunk freeing into the state machine in order to
      possibly trigger packet discards and thus indirectly a queue
      flush on error. It would surely be better to discard chunks
      as in the current, perhaps better controlled environment, but
      going back and forth, it's simply architecturally not possible.
      I tried various trailing JUNK attack cases and it seems to
      look good now.
      
      Joint work with Vlad Yasevich.
      
      Fixes: 2e3216cd ("sctp: Follow security requirement of responding with 1 packet")
      Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: default avatarVlad Yasevich <vyasevich@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      565d3c2b
    • Daniel Borkmann's avatar
      net: sctp: fix panic on duplicate ASCONF chunks · 790395f9
      Daniel Borkmann authored
      commit b69040d8 upstream.
      
      When receiving a e.g. semi-good formed connection scan in the
      form of ...
      
        -------------- INIT[ASCONF; ASCONF_ACK] ------------->
        <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
        -------------------- COOKIE-ECHO -------------------->
        <-------------------- COOKIE-ACK ---------------------
        ---------------- ASCONF_a; ASCONF_b ----------------->
      
      ... where ASCONF_a equals ASCONF_b chunk (at least both serials
      need to be equal), we panic an SCTP server!
      
      The problem is that good-formed ASCONF chunks that we reply with
      ASCONF_ACK chunks are cached per serial. Thus, when we receive a
      same ASCONF chunk twice (e.g. through a lost ASCONF_ACK), we do
      not need to process them again on the server side (that was the
      idea, also proposed in the RFC). Instead, we know it was cached
      and we just resend the cached chunk instead. So far, so good.
      
      Where things get nasty is in SCTP's side effect interpreter, that
      is, sctp_cmd_interpreter():
      
      While incoming ASCONF_a (chunk = event_arg) is being marked
      !end_of_packet and !singleton, and we have an association context,
      we do not flush the outqueue the first time after processing the
      ASCONF_ACK singleton chunk via SCTP_CMD_REPLY. Instead, we keep it
      queued up, although we set local_cork to 1. Commit 2e3216cd
      changed the precedence, so that as long as we get bundled, incoming
      chunks we try possible bundling on outgoing queue as well. Before
      this commit, we would just flush the output queue.
      
      Now, while ASCONF_a's ASCONF_ACK sits in the corked outq, we
      continue to process the same ASCONF_b chunk from the packet. As
      we have cached the previous ASCONF_ACK, we find it, grab it and
      do another SCTP_CMD_REPLY command on it. So, effectively, we rip
      the chunk->list pointers and requeue the same ASCONF_ACK chunk
      another time. Since we process ASCONF_b, it's correctly marked
      with end_of_packet and we enforce an uncork, and thus flush, thus
      crashing the kernel.
      
      Fix it by testing if the ASCONF_ACK is currently pending and if
      that is the case, do not requeue it. When flushing the output
      queue we may relink the chunk for preparing an outgoing packet,
      but eventually unlink it when it's copied into the skb right
      before transmission.
      
      Joint work with Vlad Yasevich.
      
      Fixes: 2e3216cd ("sctp: Follow security requirement of responding with 1 packet")
      Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: default avatarVlad Yasevich <vyasevich@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      790395f9
    • Daniel Borkmann's avatar
      net: sctp: fix skb_over_panic when receiving malformed ASCONF chunks · 240432f9
      Daniel Borkmann authored
      commit 9de7922b upstream.
      
      Commit 6f4c618d ("SCTP : Add paramters validity check for
      ASCONF chunk") added basic verification of ASCONF chunks, however,
      it is still possible to remotely crash a server by sending a
      special crafted ASCONF chunk, even up to pre 2.6.12 kernels:
      
      skb_over_panic: text:ffffffffa01ea1c3 len:31056 put:30768
       head:ffff88011bd81800 data:ffff88011bd81800 tail:0x7950
       end:0x440 dev:<NULL>
       ------------[ cut here ]------------
      kernel BUG at net/core/skbuff.c:129!
      [...]
      Call Trace:
       <IRQ>
       [<ffffffff8144fb1c>] skb_put+0x5c/0x70
       [<ffffffffa01ea1c3>] sctp_addto_chunk+0x63/0xd0 [sctp]
       [<ffffffffa01eadaf>] sctp_process_asconf+0x1af/0x540 [sctp]
       [<ffffffff8152d025>] ? _read_unlock_bh+0x15/0x20
       [<ffffffffa01e0038>] sctp_sf_do_asconf+0x168/0x240 [sctp]
       [<ffffffffa01e3751>] sctp_do_sm+0x71/0x1210 [sctp]
       [<ffffffff8147645d>] ? fib_rules_lookup+0xad/0xf0
       [<ffffffffa01e6b22>] ? sctp_cmp_addr_exact+0x32/0x40 [sctp]
       [<ffffffffa01e8393>] sctp_assoc_bh_rcv+0xd3/0x180 [sctp]
       [<ffffffffa01ee986>] sctp_inq_push+0x56/0x80 [sctp]
       [<ffffffffa01fcc42>] sctp_rcv+0x982/0xa10 [sctp]
       [<ffffffffa01d5123>] ? ipt_local_in_hook+0x23/0x28 [iptable_filter]
       [<ffffffff8148bdc9>] ? nf_iterate+0x69/0xb0
       [<ffffffff81496d10>] ? ip_local_deliver_finish+0x0/0x2d0
       [<ffffffff8148bf86>] ? nf_hook_slow+0x76/0x120
       [<ffffffff81496d10>] ? ip_local_deliver_finish+0x0/0x2d0
       [<ffffffff81496ded>] ip_local_deliver_finish+0xdd/0x2d0
       [<ffffffff81497078>] ip_local_deliver+0x98/0xa0
       [<ffffffff8149653d>] ip_rcv_finish+0x12d/0x440
       [<ffffffff81496ac5>] ip_rcv+0x275/0x350
       [<ffffffff8145c88b>] __netif_receive_skb+0x4ab/0x750
       [<ffffffff81460588>] netif_receive_skb+0x58/0x60
      
      This can be triggered e.g., through a simple scripted nmap
      connection scan injecting the chunk after the handshake, for
      example, ...
      
        -------------- INIT[ASCONF; ASCONF_ACK] ------------->
        <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------
        -------------------- COOKIE-ECHO -------------------->
        <-------------------- COOKIE-ACK ---------------------
        ------------------ ASCONF; UNKNOWN ------------------>
      
      ... where ASCONF chunk of length 280 contains 2 parameters ...
      
        1) Add IP address parameter (param length: 16)
        2) Add/del IP address parameter (param length: 255)
      
      ... followed by an UNKNOWN chunk of e.g. 4 bytes. Here, the
      Address Parameter in the ASCONF chunk is even missing, too.
      This is just an example and similarly-crafted ASCONF chunks
      could be used just as well.
      
      The ASCONF chunk passes through sctp_verify_asconf() as all
      parameters passed sanity checks, and after walking, we ended
      up successfully at the chunk end boundary, and thus may invoke
      sctp_process_asconf(). Parameter walking is done with
      WORD_ROUND() to take padding into account.
      
      In sctp_process_asconf()'s TLV processing, we may fail in
      sctp_process_asconf_param() e.g., due to removal of the IP
      address that is also the source address of the packet containing
      the ASCONF chunk, and thus we need to add all TLVs after the
      failure to our ASCONF response to remote via helper function
      sctp_add_asconf_response(), which basically invokes a
      sctp_addto_chunk() adding the error parameters to the given
      skb.
      
      When walking to the next parameter this time, we proceed
      with ...
      
        length = ntohs(asconf_param->param_hdr.length);
        asconf_param = (void *)asconf_param + length;
      
      ... instead of the WORD_ROUND()'ed length, thus resulting here
      in an off-by-one that leads to reading the follow-up garbage
      parameter length of 12336, and thus throwing an skb_over_panic
      for the reply when trying to sctp_addto_chunk() next time,
      which implicitly calls the skb_put() with that length.
      
      Fix it by using sctp_walk_params() [ which is also used in
      INIT parameter processing ] macro in the verification *and*
      in ASCONF processing: it will make sure we don't spill over,
      that we walk parameters WORD_ROUND()'ed. Moreover, we're being
      more defensive and guard against unknown parameter types and
      missized addresses.
      
      Joint work with Vlad Yasevich.
      
      Fixes: b896b82b ("[SCTP] ADDIP: Support for processing incoming ASCONF_ACK chunks.")
      Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: default avatarVlad Yasevich <vyasevich@gmail.com>
      Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      240432f9
    • Ben Hutchings's avatar
      drivers/net: macvtap and tun depend on INET · 6b99e68d
      Ben Hutchings authored
      commit de11b0e8 upstream.
      
      These drivers now call ipv6_proxy_select_ident(), which is defined
      only if CONFIG_INET is enabled.  However, they have really depended
      on CONFIG_INET for as long as they have allowed sending GSO packets
      from userland.
      Reported-by: default avatarkbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      Fixes: f43798c2 ("tun: Allow GSO using virtio_net_hdr")
      Fixes: b9fb9ee0 ("macvtap: add GSO/csum offload support")
      Fixes: 5188cd44 ("drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets")
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      6b99e68d
  2. 05 Nov, 2014 35 commits