This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
yakkety' to 'verification-done-yakkety'. If the problem still exists,
change the tag 'verification-needed-yakkety' to 'verification-failed-

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See for documentation how
to enable and use -proposed. Thank you!

You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.

  ip_rcv_finish() NULL pointer kernel panic

Status in linux package in Ubuntu:
  Fix Released
Status in linux source package in Trusty:
Status in linux source package in Xenial:
  Fix Committed
Status in linux source package in Yakkety:
  Fix Committed
Status in linux source package in Zesty:
  Fix Released

Bug description:

  When using iptables rules affecting bridge traffic, and if affected
  traffic is flowing through bridge while br_netfilter module is loaded
  or unloaded, a kernel panic may occur.

  [Test Case]

  It's difficult to reproduce because of a very small race condition
  window during br_netfilter load/unload when the module is receiving
  traffic but has not yet registered its hooks (or, has unregistered its
  hooks but still has traffic it's processing).  A system must be set up
  using a bridge, and iptable netfilter rules must be set up to process
  the bridge traffic.  Then the system should be rebooted until the
  problem occurs, or the br_netfilter module should be loaded/unloaded
  until the problem occurs.

  [Regression Potential]

  Changing how the br_netfilter module switches its fake dst for a real
  dst may, if done incorrectly, result in more kernel panics if other
  code tries to process the br_netfilter module's fake dst.

  [Other Info]

  The br_netfilter module processes packets traveling through its
  bridge, and while processing each skb it places a special fake dst
  onto the skb.  When the skb leaves the bridge, it removes the fake dst
  and places a real dst onto it.  However, it uses a hook to do this,
  and when the br_netfilter module is unloading it unregisters that
  hook.  Any skbs that are currently being processed in the bridge by
  the br_netfilter module, but that leave the bridge after the hook is
  unregistered (or, during br_netfilter module load, before the hook is
  registered) will still have the fake dst; when other code then tries
  to process that dst, it causes a kernel panic because the dst is

  Recent upstream discussion:

  Upstream patch:
  upstream commit is a13b2082ece95247779b9995c4e91b4246bed023

  example panic report:

  [ 214.518262] BUG: unable to handle kernel NULL pointer dereference at (null)
  [ 214.612199] IP: [< (null)>] (null)
  [ 214.672744] PGD 0 [ 214.696887] Oops: 0010 [#1] SMP [ 214.735697] Modules 
linked in: br_netfilter(+) tun 8021q bridge stp llc bonding iTCO_wdt 
iTCO_vendor_support tpm_tis tpm kvm_intel kvm irqbypass sb_edac edac_core ixgbe 
mdio ipmi_si ipmi_msghandler lpc_ich mfd_core mousedev evdev igb dca 
procmemro(O) nokeyctl(O) noptrace(O)
  [ 215.029240] CPU: 34 PID: 0 Comm: swapper/34 Tainted: G O 4.4.39 #1
  [ 215.116720] Hardware name: Cisco Systems Inc UCSC-C220-M3L/UCSC-C220-M3L, 
BIOS C220M3.2.0.13a.0.0713160937 07/13/16
  [ 215.241644] task: ffff882038fb4380 ti: ffff8810392b0000 task.ti: 
  [ 215.331207] RIP: 0010:[<0000000000000000>] [< (null)>] (null)
  [ 215.420877] RSP: 0018:ffff88103fec3880 EFLAGS: 00010286
  [ 215.484436] RAX: ffff881011631000 RBX: ffff881011067100 RCX: 
  [ 215.569836] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 
  [ 215.655234] RBP: ffff88103fec38a8 R08: 0000000000000008 R09: 
  [ 215.740629] R10: 0000000000000000 R11: 0000000000000000 R12: 
  [ 215.826030] R13: ffffffff81c9be00 R14: ffffffff81c9be00 R15: 
  [ 215.911432] FS: 0000000000000000(0000) GS:ffff88103fec0000(0000) 
  [ 216.008274] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 216.077032] CR2: 0000000000000000 CR3: 0000001011b9d000 CR4: 
  [ 216.162430] Stack:
  [ 216.186461] ffffffff8157d7f9 ffff881011067100 ffff881018917dce 
  [ 216.275407] ffffffff81c9be00 ffff88103fec3918 ffffffff8157e0db 
  [ 216.364352] 0000000000000000 0000000000000000 0000000000000000 
  [ 216.453301] Call Trace:
  [ 216.482536] <IRQ> [ 216.505533] [<ffffffff8157d7f9>] ? 
  [ 216.575442] [<ffffffff8157e0db>] ip_rcv+0x25b/0x370
  [ 216.634842] [<ffffffff81540e0b>] __netif_receive_skb_core+0x2cb/0xa20
  [ 216.712965] [<ffffffff81541578>] __netif_receive_skb+0x18/0x60
  [ 216.783801] [<ffffffff815415e3>] netif_receive_skb_internal+0x23/0x80
  [ 216.861921] [<ffffffff8154165c>] netif_receive_skb+0x1c/0x70
  [ 216.930686] [<ffffffffa02f6439>] br_handle_frame_finish+0x1b9/0x5b0 [bridge]
  [ 217.016091] [<ffffffff81187a00>] ? ___slab_alloc+0x1d0/0x440
  [ 217.084849] [<ffffffffa0584074>] br_nf_pre_routing_finish+0x174/0x3d0 
  [ 217.178568] [<ffffffffa0584c07>] ? br_nf_pre_routing+0x97/0x470 
  [ 217.266052] [<ffffffffa02f6280>] ? br_handle_local_finish+0x80/0x80 [bridge]
  [ 217.351450] [<ffffffffa0584d17>] br_nf_pre_routing+0x1a7/0x470 
  [ 217.437891] [<ffffffff81572f6d>] nf_iterate+0x5d/0x70
  [ 217.499367] [<ffffffff81572fe4>] nf_hook_slow+0x64/0xc0
  [ 217.562928] [<ffffffffa02f69e9>] br_handle_frame+0x1b9/0x290 [bridge]
  [ 217.641048] [<ffffffffa02f6280>] ? br_handle_local_finish+0x80/0x80 [bridge]
  [ 217.726446] [<ffffffff81540e82>] __netif_receive_skb_core+0x342/0xa20
  [ 217.804566] [<ffffffff815a7916>] ? tcp4_gro_receive+0x126/0x1d0
  [ 217.876445] [<ffffffff815b7446>] ? inet_gro_receive+0x1c6/0x250
  [ 217.948322] [<ffffffff81541578>] __netif_receive_skb+0x18/0x60
  [ 218.019161] [<ffffffff815415e3>] netif_receive_skb_internal+0x23/0x80
  [ 218.097281] [<ffffffff81542213>] napi_gro_receive+0xc3/0x110
  [ 218.166051] [<ffffffffa00a801f>] ixgbe_clean_rx_irq+0x52f/0xa70 [ixgbe]
  [ 218.246255] [<ffffffffa00a9248>] ixgbe_poll+0x438/0x790 [ixgbe]
  [ 218.318131] [<ffffffff81541a6e>] net_rx_action+0x1ee/0x320
  [ 218.384813] [<ffffffff8109c837>] ? handle_irq_event_percpu+0x167/0x1d0
  [ 218.463973] [<ffffffff8105c3c1>] __do_softirq+0x101/0x280
  [ 218.529608] [<ffffffff8105c69e>] irq_exit+0x8e/0x90
  [ 218.589007] [<ffffffff816dd504>] do_IRQ+0x54/0xd0
  [ 218.646323] [<ffffffff816dba02>] common_interrupt+0x82/0x82

To manage notifications about this bug go to:

Mailing list:
Post to     :
Unsubscribe :
More help   :

Reply via email to