Re: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_add

[Dmitry Vyukov]

On Mon, Sep 10, 2018 at 10:31 AM syzbot
<syzbot+c827a78260579449ad39@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    f6f3bac08ff9 tools/bpf: bpftool: add net support
> git tree:       bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=17940056400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
> dashboard link: https://syzkaller.appspot.com/bug?extid=c827a78260579449ad39
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1611c7e1400000

This is still very actively happening. See the dashboard link for info
about more crashes.

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+c827a78260579449ad39@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> **   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
> **********************************************************
> BUG: unable to handle kernel paging request at ffffc90001930002
> PGD 1da948067 P4D 1da948067 PUD 1da949067 PMD 1d49da067 PTE 0
> Oops: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 12601 Comm: syz-executor3 Not tainted 4.19.0-rc2+ #93
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:bpf_prog_kallsyms_candidate kernel/bpf/core.c:472 [inline]
> RIP: 0010:bpf_prog_kallsyms_add+0xbe/0x9b0 kernel/bpf/core.c:483
> Code: d0 31 c0 e8 14 68 f3 ff 49 8d 7c 24 02 48 89 f8 48 89 fa 48 c1 e8 03
> 83 e2 07 0f b6 04 18 38 d0 7f 08 84 c0 0f 85 39 07 00 00 <41> 0f b6 5c 24
> 02 31 ff 83 e3 01 89 de e8 b0 68 f3 ff 84 db 0f 84
> RSP: 0018:ffff8801bc2af9c0 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff818c8b39
> RDX: 0000000000000002 RSI: ffffffff818b671c RDI: ffffc90001930002
> RBP: ffff8801bc2afb30 R08: ffff8801bf750100 R09: ffffed003b584732
> R10: ffffed003b584732 R11: ffff8801dac23993 R12: ffffc90001930000
> R13: ffff8801bc2afd18 R14: 0000000000000000 R15: 1ffff10037855f3d
> FS:  00007fb5d21c9700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffc90001930002 CR3: 00000001bcd1c000 CR4: 00000000001406f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   bpf_prog_load+0x13d1/0x1cb0 kernel/bpf/syscall.c:1442
>   __do_sys_bpf kernel/bpf/syscall.c:2371 [inline]
>   __se_sys_bpf kernel/bpf/syscall.c:2333 [inline]
>   __x64_sys_bpf+0x36c/0x510 kernel/bpf/syscall.c:2333
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457099
> Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fb5d21c8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 00007fb5d21c96d4 RCX: 0000000000457099
> RDX: 0000000000000048 RSI: 0000000020000000 RDI: 0000000000000005
> RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000004cb9c8 R14: 00000000004c335d R15: 0000000000000000
> Modules linked in:
> Dumping ftrace buffer:
>     (ftrace buffer empty)
> CR2: ffffc90001930002
> ---[ end trace fcb4474011e9b55c ]---
> RIP: 0010:bpf_prog_kallsyms_candidate kernel/bpf/core.c:472 [inline]
> RIP: 0010:bpf_prog_kallsyms_add+0xbe/0x9b0 kernel/bpf/core.c:483
> Code: d0 31 c0 e8 14 68 f3 ff 49 8d 7c 24 02 48 89 f8 48 89 fa 48 c1 e8 03
> 83 e2 07 0f b6 04 18 38 d0 7f 08 84 c0 0f 85 39 07 00 00 <41> 0f b6 5c 24
> 02 31 ff 83 e3 01 89 de e8 b0 68 f3 ff 84 db 0f 84
> RSP: 0018:ffff8801bc2af9c0 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff818c8b39
> RDX: 0000000000000002 RSI: ffffffff818b671c RDI: ffffc90001930002
> RBP: ffff8801bc2afb30 R08: ffff8801bf750100 R09: ffffed003b584732
> R10: ffffed003b584732 R11: ffff8801dac23993 R12: ffffc90001930000
> R13: ffff8801bc2afd18 R14: 0000000000000000 R15: 1ffff10037855f3d
> FS:  00007fb5d21c9700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffc90001930002 CR3: 00000001bcd1c000 CR4: 00000000001406f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> 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
>
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>
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