Re: general protection fault in bpf_tcp_close

[Daniel Borkmann]

[ +John ]

On 05/26/2018 11:13 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:ÂÂÂ fd0bfa8d6e04 Merge branch 'bpf-af-xdp-cleanups'
> git tree:ÂÂÂÂÂÂ bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=11da9427800000
> kernel config:Â https://syzkaller.appspot.com/x/.config?x=b632d8e2c2ab2c1
> dashboard link: https://syzkaller.appspot.com/bug?extid=0ce137753c78f7b6acc1
> compiler:ÂÂÂÂÂÂ gcc (GCC) 8.0.1 20180413 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0ce137753c78f7b6acc1@xxxxxxxxxxxxxxxxxxxxxxxxx

Should be fixed by: https://patchwork.ozlabs.org/patch/920695/

> kasan: CONFIG_KASAN_INLINE enabled
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
> ÂÂ (ftrace buffer empty)
> Modules linked in:
> CPU: 0 PID: 12139 Comm: syz-executor2 Not tainted 4.17.0-rc4+ #17
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__hlist_del include/linux/list.h:649 [inline]
> RIP: 0010:hlist_del_rcu include/linux/rculist.h:427 [inline]
> RIP: 0010:bpf_tcp_close+0x7d2/0xf80 kernel/bpf/sockmap.c:271
> RSP: 0018:ffff8801a8f8ef70 EFLAGS: 00010a02
> RAX: ffffed00351f1dfd RBX: dffffc0000000000 RCX: dead000000000200
> RDX: 0000000000000000 RSI: 1bd5a00000000040 RDI: ffff8801cb710910
> RBP: ffff8801a8f8f110 R08: ffffed003350ac9d R09: ffffed003350ac9c
> R10: ffffed003350ac9c R11: ffff88019a8564e3 R12: ffff8801cb710380
> R13: ffff8801b17ea6e0 R14: ffff8801cb710398 R15: ffff8801cb710900
> FS:Â 00007f9890c43700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
> CS:Â 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fde1a668000 CR3: 000000019dca2000 CR4: 00000000001406f0
> DR0: 00000000200001c0 DR1: 00000000200001c0 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> Call Trace:
> Âinet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
> Âinet6_release+0x50/0x70 net/ipv6/af_inet6.c:459
> Âsock_release+0x96/0x1b0 net/socket.c:594
> Âsock_close+0x16/0x20 net/socket.c:1149
> Â__fput+0x34d/0x890 fs/file_table.c:209
> Â____fput+0x15/0x20 fs/file_table.c:243
> Âtask_work_run+0x1e4/0x290 kernel/task_work.c:113
> Âexit_task_work include/linux/task_work.h:22 [inline]
> Âdo_exit+0x1aee/0x2730 kernel/exit.c:865
> Âdo_group_exit+0x16f/0x430 kernel/exit.c:968
> Âget_signal+0x886/0x1960 kernel/signal.c:2469
> Âdo_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
> Âexit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
> Âprepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
> Âsyscall_return_slowpath arch/x86/entry/common.c:265 [inline]
> Âdo_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
> Âentry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x455a09
> RSP: 002b:00007f9890c42ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: fffffffffffffe00 RBX: 000000000072bec8 RCX: 0000000000455a09
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072bec8
> RBP: 000000000072bec8 R08: 0000000000000000 R09: 000000000072bea0
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffcb48ac3ff R14: 00007f9890c439c0 R15: 0000000000000000
> Code: ff 48 c1 e9 03 80 3c 19 00 0f 85 a9 05 00 00 49 8b 4f 18 48 8b 85 98 fe ff ff 48 89 ce c6 00 00 48 c1 ee 03 48 89 95 d8 fe ff ff <80> 3c 1e 00 0f 85 c6 05 00 00 48 8b 85 98 fe ff ff 48 85 d2 48
> RIP: __hlist_del include/linux/list.h:649 [inline] RSP: ffff8801a8f8ef70
> RIP: hlist_del_rcu include/linux/rculist.h:427 [inline] RSP: ffff8801a8f8ef70
> RIP: bpf_tcp_close+0x7d2/0xf80 kernel/bpf/sockmap.c:271 RSP: ffff8801a8f8ef70
> ---[ end trace e81227e93c7e7b75 ]---
> 
> 
> ---
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