Re: [syzbot] kernel BUG in vhost_vsock_handle_tx_kick

[Bobby Eshleman]

On Tue, Jan 03, 2023 at 08:21:25PM -0800, Cong Wang wrote:
> On Tue, Jan 03, 2023 at 04:08:51PM -0800, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    c76083fac3ba Add linux-next specific files for 20221226
> > git tree:       linux-next
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1723da42480000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=c217c755f1884ab6
> > dashboard link: https://syzkaller.appspot.com/bug?extid=30b72abaa17c07fe39dd
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14fc414c480000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1604b20a480000
> > 
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/e388f26357fd/disk-c76083fa.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/e24f0bae36d5/vmlinux-c76083fa.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/a5a69a059716/bzImage-c76083fa.xz
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+30b72abaa17c07fe39dd@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> +bobby.eshleman@xxxxxxxxx
> 
> Bobby, please take a look.
> 
> Thanks.

Roger that, I'll take a gander asap.

> 
> > 
> > skbuff: skb_over_panic: text:ffffffff8768d6f1 len:25109 put:25109 head:ffff88802b5ac000 data:ffff88802b5ac02c tail:0x6241 end:0xc0 dev:<NULL>
> > ------------[ cut here ]------------
> > kernel BUG at net/core/skbuff.c:121!
> > invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> > CPU: 0 PID: 5072 Comm: vhost-5071 Not tainted 6.2.0-rc1-next-20221226-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> > RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:121
> > Code: f7 4c 8b 4c 24 10 8b 4b 70 41 56 45 89 e8 4c 89 e2 41 57 48 89 ee 48 c7 c7 40 04 5b 8b ff 74 24 10 ff 74 24 20 e8 09 8e bf ff <0f> 0b e8 1a 67 82 f7 4c 8b 64 24 18 e8 80 3d d0 f7 48 c7 c1 40 12
> > RSP: 0018:ffffc90003cefca0 EFLAGS: 00010282
> > RAX: 000000000000008d RBX: ffff88802b674500 RCX: 0000000000000000
> > RDX: ffff8880236bba80 RSI: ffffffff81663b9c RDI: fffff5200079df86
> > RBP: ffffffff8b5b1280 R08: 000000000000008d R09: 0000000000000000
> > R10: 0000000080000000 R11: 0000000000000000 R12: ffffffff8768d6f1
> > R13: 0000000000006215 R14: ffffffff8b5b0400 R15: 00000000000000c0
> > FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000020000380 CR3: 000000002985f000 CR4: 00000000003506f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  skb_over_panic net/core/skbuff.c:126 [inline]
> >  skb_put.cold+0x24/0x24 net/core/skbuff.c:2218
> >  virtio_vsock_skb_rx_put include/linux/virtio_vsock.h:56 [inline]
> >  vhost_vsock_alloc_skb drivers/vhost/vsock.c:374 [inline]
> >  vhost_vsock_handle_tx_kick+0xad1/0xd00 drivers/vhost/vsock.c:509
> >  vhost_worker+0x241/0x3e0 drivers/vhost/vhost.c:364
> >  kthread+0x2e8/0x3a0 kernel/kthread.c:376
> >  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
> >  </TASK>
> > Modules linked in:
> > ---[ end trace 0000000000000000 ]---
> > RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:121
> > Code: f7 4c 8b 4c 24 10 8b 4b 70 41 56 45 89 e8 4c 89 e2 41 57 48 89 ee 48 c7 c7 40 04 5b 8b ff 74 24 10 ff 74 24 20 e8 09 8e bf ff <0f> 0b e8 1a 67 82 f7 4c 8b 64 24 18 e8 80 3d d0 f7 48 c7 c1 40 12
> > RSP: 0018:ffffc90003cefca0 EFLAGS: 00010282
> > RAX: 000000000000008d RBX: ffff88802b674500 RCX: 0000000000000000
> > RDX: ffff8880236bba80 RSI: ffffffff81663b9c RDI: fffff5200079df86
> > RBP: ffffffff8b5b1280 R08: 000000000000008d R09: 0000000000000000
> > R10: 0000000080000000 R11: 0000000000000000 R12: ffffffff8768d6f1
> > R13: 0000000000006215 R14: ffffffff8b5b0400 R15: 00000000000000c0
> > FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007fdc6f4a4298 CR3: 000000002985f000 CR4: 00000000003506e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > 
> > 
> > ---
> > This report 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@xxxxxxxxxxxxxxxx.
> > 
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > syzbot can test patches for this issue, for details see:
> > https://goo.gl/tpsmEJ#testing-patches