On Tue, Oct 29, 2019 at 10:45:19AM +0200, Ido Schimmel wrote: > On Tue, Oct 29, 2019 at 09:43:27AM +0100, Dmitry Vyukov wrote: > > On Tue, Oct 29, 2019 at 9:38 AM syzbot > > <syzbot+9ed8f68ab30761f3678e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 38207291 bpf: Prepare btf_ctx_access for non raw_tp use case > > > git tree: bpf-next > > > console output: https://syzkaller.appspot.com/x/log.txt?x=14173c0f600000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=41648156aa09be10 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=9ed8f68ab30761f3678e > > > compiler: gcc (GCC) 9.0.0 20181231 (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+9ed8f68ab30761f3678e@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > +Jiří Pírko, this seems to be related to netdevsim. > > Will check it. Didn't have a lot of time today, but I think the issue is a race condition (note that syzbot only triggered it twice so far). Upon reload nsim_dev_port_del_all() is called and starts deleting ports from the ports list without holding the ports list mutex. It is possible that during this time nsim_dev_trap_report_work() is executing from a workqueue and accessing freed memory despite holding the ports list mutex. I'll try to reproduce and send a fix later this week. > > > > > > kasan: CONFIG_KASAN_INLINE enabled > > > kasan: GPF could be caused by NULL-ptr deref or user memory access > > > general protection fault: 0000 [#1] PREEMPT SMP KASAN > > > CPU: 1 PID: 9149 Comm: kworker/1:3 Not tainted 5.4.0-rc1+ #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > > Google 01/01/2011 > > > Workqueue: events nsim_dev_trap_report_work > > > RIP: 0010:nsim_dev_trap_report_work+0xc4/0xaf0 > > > drivers/net/netdevsim/dev.c:409 > > > Code: 89 45 d0 0f 84 8b 07 00 00 49 bc 00 00 00 00 00 fc ff df e8 3e ae ef > > > fc 48 8b 45 d0 48 05 68 01 00 00 48 89 45 90 48 c1 e8 03 <42> 80 3c 20 00 > > > 0f 85 b1 09 00 00 48 8b 45 d0 48 8b 98 68 01 00 00 > > > RSP: 0018:ffff88806c98fc90 EFLAGS: 00010a06 > > > RAX: 1bd5a0000000004d RBX: 0000000000000000 RCX: ffffffff84836e22 > > > RDX: 0000000000000000 RSI: ffffffff84836db2 RDI: 0000000000000001 > > > RBP: ffff88806c98fd30 R08: ffff88806c9863c0 R09: ffffed100d75f3d9 > > > R10: ffffed100d75f3d8 R11: ffff88806baf9ec7 R12: dffffc0000000000 > > > R13: ffff88806baf9ec0 R14: ffff8880a9a13900 R15: ffff8880ae934500 > > > FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 00007efdd0c9e000 CR3: 000000009cc1b000 CR4: 00000000001406e0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 > > > worker_thread+0x98/0xe40 kernel/workqueue.c:2415 > > > kthread+0x361/0x430 kernel/kthread.c:255 > > > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > > Modules linked in: > > > ---[ end trace ba29cd1c27f63d86 ]--- > > > RIP: 0010:nsim_dev_trap_report_work+0xc4/0xaf0 > > > drivers/net/netdevsim/dev.c:409 > > > Code: 89 45 d0 0f 84 8b 07 00 00 49 bc 00 00 00 00 00 fc ff df e8 3e ae ef > > > fc 48 8b 45 d0 48 05 68 01 00 00 48 89 45 90 48 c1 e8 03 <42> 80 3c 20 00 > > > 0f 85 b1 09 00 00 48 8b 45 d0 48 8b 98 68 01 00 00 > > > RSP: 0018:ffff88806c98fc90 EFLAGS: 00010a06 > > > RAX: 1bd5a0000000004d RBX: 0000000000000000 RCX: ffffffff84836e22 > > > RDX: 0000000000000000 RSI: ffffffff84836db2 RDI: 0000000000000001 > > > RBP: ffff88806c98fd30 R08: ffff88806c9863c0 R09: ffffed100d75f3d9 > > > R10: ffffed100d75f3d8 R11: ffff88806baf9ec7 R12: dffffc0000000000 > > > R13: ffff88806baf9ec0 R14: ffff8880a9a13900 R15: ffff8880ae934500 > > > FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 00007efdd0c9e000 CR3: 000000009cc1b000 CR4: 00000000001406e0 > > > 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@xxxxxxxxxxxxxxxx. > > > > > > syzbot will keep track of this bug report. 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/0000000000001c46d5059608892f%40google.com.
