Re: general protection fault in bpf_tcp_close

[Dmitry Vyukov]

On Mon, May 28, 2018 at 12:15 AM, Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
> [ +John ]
>
> On 05/26/2018 11:13 AM, syzbot wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit:    fd0bfa8d6e04 Merge branch 'bpf-af-xdp-cleanups'
>> git tree:       bpf-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=11da9427800000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=b632d8e2c2ab2c1
>> dashboard link: https://syzkaller.appspot.com/bug?extid=0ce137753c78f7b6acc1
>> compiler:       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/

#syz fix: bpf: sockhash fix race with bpf_tcp_close and map delete


>> 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:
>>    (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:  00007f9890c43700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
>> CS:  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:
>>  inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
>>  inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459
>>  sock_release+0x96/0x1b0 net/socket.c:594
>>  sock_close+0x16/0x20 net/socket.c:1149
>>  __fput+0x34d/0x890 fs/file_table.c:209
>>  ____fput+0x15/0x20 fs/file_table.c:243
>>  task_work_run+0x1e4/0x290 kernel/task_work.c:113
>>  exit_task_work include/linux/task_work.h:22 [inline]
>>  do_exit+0x1aee/0x2730 kernel/exit.c:865
>>  do_group_exit+0x16f/0x430 kernel/exit.c:968
>>  get_signal+0x886/0x1960 kernel/signal.c:2469
>>  do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
>>  exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
>>  prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
>>  syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
>>  do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
>>  entry_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 ]---
>>
>>
>> ---
>> This bug is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>>
>> syzbot will keep track of this bug report. See:
>> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot.
>
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