Public bug reported: 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 invalid.
Recent upstream discussion: https://www.spinics.net/lists/netdev/msg416912.html Upstream patch (not yet merged into net-next): https://patchwork.ozlabs.org/patch/738275/ 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: ffff8810392b0000 [ 215.331207] RIP: 0010:[<0000000000000000>] [< (null)>] (null) [ 215.420877] RSP: 0018:ffff88103fec3880 EFLAGS: 00010286 [ 215.484436] RAX: ffff881011631000 RBX: ffff881011067100 RCX: 0000000000000000 [ 215.569836] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff881011067100 [ 215.655234] RBP: ffff88103fec38a8 R08: 0000000000000008 R09: ffff8810116300a0 [ 215.740629] R10: 0000000000000000 R11: 0000000000000000 R12: ffff881018917dce [ 215.826030] R13: ffffffff81c9be00 R14: ffffffff81c9be00 R15: ffff881011630078 [ 215.911432] FS: 0000000000000000(0000) GS:ffff88103fec0000(0000) knlGS:0000000000000000 [ 216.008274] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 216.077032] CR2: 0000000000000000 CR3: 0000001011b9d000 CR4: 00000000001406e0 [ 216.162430] Stack: [ 216.186461] ffffffff8157d7f9 ffff881011067100 ffff881018917dce ffff881011630000 [ 216.275407] ffffffff81c9be00 ffff88103fec3918 ffffffff8157e0db 0000000000000000 [ 216.364352] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 216.453301] Call Trace: [ 216.482536] <IRQ> [ 216.505533] [<ffffffff8157d7f9>] ? ip_rcv_finish+0x99/0x320 [ 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 [br_netfilter] [ 217.178568] [<ffffffffa0584c07>] ? br_nf_pre_routing+0x97/0x470 [br_netfilter] [ 217.266052] [<ffffffffa02f6280>] ? br_handle_local_finish+0x80/0x80 [bridge] [ 217.351450] [<ffffffffa0584d17>] br_nf_pre_routing+0x1a7/0x470 [br_netfilter] [ 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 ** Affects: linux (Ubuntu) Importance: Medium Assignee: Dan Streetman (ddstreet) Status: In Progress ** Tags: sts ** Changed in: linux (Ubuntu) Assignee: (unassigned) => Dan Streetman (ddstreet) ** Changed in: linux (Ubuntu) Importance: Undecided => Medium ** Changed in: linux (Ubuntu) Status: New => In Progress ** Tags added: sts -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1672470 Title: ip_rcv_finish() NULL pointer kernel panic Status in linux package in Ubuntu: In Progress Bug description: 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 invalid. Recent upstream discussion: https://www.spinics.net/lists/netdev/msg416912.html Upstream patch (not yet merged into net-next): https://patchwork.ozlabs.org/patch/738275/ 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: ffff8810392b0000 [ 215.331207] RIP: 0010:[<0000000000000000>] [< (null)>] (null) [ 215.420877] RSP: 0018:ffff88103fec3880 EFLAGS: 00010286 [ 215.484436] RAX: ffff881011631000 RBX: ffff881011067100 RCX: 0000000000000000 [ 215.569836] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff881011067100 [ 215.655234] RBP: ffff88103fec38a8 R08: 0000000000000008 R09: ffff8810116300a0 [ 215.740629] R10: 0000000000000000 R11: 0000000000000000 R12: ffff881018917dce [ 215.826030] R13: ffffffff81c9be00 R14: ffffffff81c9be00 R15: ffff881011630078 [ 215.911432] FS: 0000000000000000(0000) GS:ffff88103fec0000(0000) knlGS:0000000000000000 [ 216.008274] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 216.077032] CR2: 0000000000000000 CR3: 0000001011b9d000 CR4: 00000000001406e0 [ 216.162430] Stack: [ 216.186461] ffffffff8157d7f9 ffff881011067100 ffff881018917dce ffff881011630000 [ 216.275407] ffffffff81c9be00 ffff88103fec3918 ffffffff8157e0db 0000000000000000 [ 216.364352] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 216.453301] Call Trace: [ 216.482536] <IRQ> [ 216.505533] [<ffffffff8157d7f9>] ? ip_rcv_finish+0x99/0x320 [ 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 [br_netfilter] [ 217.178568] [<ffffffffa0584c07>] ? br_nf_pre_routing+0x97/0x470 [br_netfilter] [ 217.266052] [<ffffffffa02f6280>] ? br_handle_local_finish+0x80/0x80 [bridge] [ 217.351450] [<ffffffffa0584d17>] br_nf_pre_routing+0x1a7/0x470 [br_netfilter] [ 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: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1672470/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
