On Wed, Nov 25, 2020 at 5:04 PM Oliver Hartkopp <socketcan@xxxxxxxxxxxx> wrote: > > Hello all, > > AFAICS the problems are caused by the WARN() statement here: > > https://elixir.bootlin.com/linux/v5.10-rc4/source/net/can/af_can.c#L546 > > The idea was to check whether CAN protocol implementations work > correctly on their filter lists. > > With the fault injection it seem like we're getting a race between > closing the socket and removing the netdevice. > > This seems to be very seldom but it does not break anything. > > Would removing the WARN(1) or replacing it with pr_warn() be ok to close > this issue? Hi Oliver, Yes, this is the intended way to deal with this: https://elixir.bootlin.com/linux/v5.10-rc5/source/include/asm-generic/bug.h#L75 Maybe a good opportunity to add some explanatory comment as well regarding how it should not happen but can. Thanks for looking into this. > On 23.11.20 12:58, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: c2e7554e Merge tag 'gfs2-v5.10-rc4-fixes' of git://git.ker.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=117f03ba500000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=75292221eb79ace2 > > dashboard link: https://syzkaller.appspot.com/bug?extid=381d06e0c8eaacb8706f > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+381d06e0c8eaacb8706f@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ------------[ cut here ]------------ > > BUG: receive list entry not found for dev vxcan1, id 002, mask C00007FF > > WARNING: CPU: 1 PID: 12946 at net/can/af_can.c:546 can_rx_unregister+0x5a4/0x700 net/can/af_can.c:546 > > Modules linked in: > > CPU: 1 PID: 12946 Comm: syz-executor.1 Not tainted 5.10.0-rc4-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > RIP: 0010:can_rx_unregister+0x5a4/0x700 net/can/af_can.c:546 > > Code: 8b 7c 24 78 44 8b 64 24 68 49 c7 c5 20 ac 56 8a e8 01 6c 97 f9 44 89 f9 44 89 e2 4c 89 ee 48 c7 c7 60 ac 56 8a e8 66 af d3 00 <0f> 0b 48 8b 7c 24 28 e8 b0 25 0f 01 e9 54 fb ff ff e8 26 e0 d8 f9 > > RSP: 0018:ffffc90017e2fb38 EFLAGS: 00010286 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > > RDX: ffff8880147a8000 RSI: ffffffff8158f3c5 RDI: fffff52002fc5f59 > > RBP: 0000000000000118 R08: 0000000000000001 R09: ffff8880b9f2011b > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 > > R13: ffff8880254c0000 R14: 1ffff92002fc5f6e R15: 00000000c00007ff > > FS: 0000000001ddc940(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000001b2f121000 CR3: 00000000152c0000 CR4: 00000000001506e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > isotp_notifier+0x2a7/0x540 net/can/isotp.c:1303 > > call_netdevice_notifier net/core/dev.c:1735 [inline] > > call_netdevice_unregister_notifiers+0x156/0x1c0 net/core/dev.c:1763 > > call_netdevice_unregister_net_notifiers net/core/dev.c:1791 [inline] > > unregister_netdevice_notifier+0xcd/0x170 net/core/dev.c:1870 > > isotp_release+0x136/0x600 net/can/isotp.c:1011 > > __sock_release+0xcd/0x280 net/socket.c:596 > > sock_close+0x18/0x20 net/socket.c:1277 > > __fput+0x285/0x920 fs/file_table.c:281 > > task_work_run+0xdd/0x190 kernel/task_work.c:151 > > tracehook_notify_resume include/linux/tracehook.h:188 [inline] > > exit_to_user_mode_loop kernel/entry/common.c:164 [inline] > > exit_to_user_mode_prepare+0x17e/0x1a0 kernel/entry/common.c:191 > > syscall_exit_to_user_mode+0x38/0x260 kernel/entry/common.c:266 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > RIP: 0033:0x417811 > > Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 > > RSP: 002b:000000000169fbf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 > > RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417811 > > RDX: 0000000000000000 RSI: 00000000000013b7 RDI: 0000000000000003 > > RBP: 0000000000000001 R08: 00000000acabb3b7 R09: 00000000acabb3bb > > R10: 000000000169fcd0 R11: 0000000000000293 R12: 000000000118c9a0 > > R13: 000000000118c9a0 R14: 00000000000003e8 R15: 000000000118bf2c > > > > > > --- > > 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. > > > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/b134c098-2f34-15ee-cfec-2103a12da326%40hartkopp.net.
