syzbot


possible deadlock in register_netdev
Status: upstream: reported C repro on 2021/08/01 10:44
Reported-by: syzbot+ed8813d241a91de15965@syzkaller.appspotmail.com
First crash: 297d, last: 287d

Cause bisection: introduced by (bisect log) [no-op commit]:
commit b9fc8b4a591811546fec2dbef7e9f809362100c9
Author: Grant Seltzer <grantseltzer@gmail.com>
Date: Mon Feb 22 19:58:46 2021 +0000

  bpf: Add kernel/modules BTF presence checks to bpftool feature command

Crash: WARNING in kvm_wait (log)
Repro: C syz .config

Fix bisection: fixed by (bisect log) [no-op commit]:
commit a3af0140663dc335e5c18277a61bb99bfcb60694
Author: Emil Velikov <emil.velikov@collabora.com>
Date: Fri Jun 4 15:49:05 2021 +0000

  drm/i915: apply WaEnableVGAAccessThroughIOPort as needed

Patch testing requests:
Created Duration User Patch Repo Result
2021/10/24 14:14 16m phind.uet@gmail.com linux-next OK

Sample crash report:
netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc2-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor917/8441 is trying to acquire lock:
ffffffff8d0cb568 (rtnl_mutex){+.+.}-{3:3}, at: register_netdev+0x11/0x50 net/core/dev.c:10474

but task is already holding lock:
ffffffff8d0a9608 (br_ioctl_mutex){+.+.}-{3:3}, at: br_ioctl_call+0x3b/0xa0 net/socket.c:1089

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (br_ioctl_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:959 [inline]
       __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
       br_ioctl_call+0x3b/0xa0 net/socket.c:1089
       dev_ifsioc+0xc1f/0xf60 net/core/dev_ioctl.c:382
       dev_ioctl+0x1b9/0xee0 net/core/dev_ioctl.c:580
       sock_do_ioctl+0x18b/0x210 net/socket.c:1128
       sock_ioctl+0x2f1/0x640 net/socket.c:1231
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:1069 [inline]
       __se_sys_ioctl fs/ioctl.c:1055 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (rtnl_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3051 [inline]
       check_prevs_add kernel/locking/lockdep.c:3174 [inline]
       validate_chain kernel/locking/lockdep.c:3789 [inline]
       __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
       lock_acquire kernel/locking/lockdep.c:5625 [inline]
       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
       __mutex_lock_common kernel/locking/mutex.c:959 [inline]
       __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
       register_netdev+0x11/0x50 net/core/dev.c:10474
       br_add_bridge+0x97/0xf0 net/bridge/br_if.c:459
       br_ioctl_stub+0x750/0x7f0 net/bridge/br_ioctl.c:390
       br_ioctl_call+0x5e/0xa0 net/socket.c:1091
       sock_ioctl+0x30c/0x640 net/socket.c:1185
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:1069 [inline]
       __se_sys_ioctl fs/ioctl.c:1055 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(br_ioctl_mutex);
                               lock(rtnl_mutex);
                               lock(br_ioctl_mutex);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor917/8441:
 #0: ffffffff8d0a9608 (br_ioctl_mutex){+.+.}-{3:3}, at: br_ioctl_call+0x3b/0xa0 net/socket.c:1089

stack backtrace:
CPU: 0 PID: 8441 Comm: syz-executor917 Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131
 check_prev_add kernel/locking/lockdep.c:3051 [inline]
 check_prevs_add kernel/locking/lockdep.c:3174 [inline]
 validate_chain kernel/locking/lockdep.c:3789 [inline]
 __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
 lock_acquire kernel/locking/lockdep.c:5625 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
 __mutex_lock_common kernel/locking/mutex.c:959 [inline]
 __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104
 register_netdev+0x11/0x50 net/core/dev.c:10474
 br_add_bridge+0x97/0xf0 net/bridge/br_if.c:459
 br_ioctl_stub+0x750/0x7f0 net/bridge/br_ioctl.c:390
 br_ioctl_call+0x5e/0xa0 net/socket.c:1091
 sock_ioctl+0x30c/0x640 net/socket.c:1185
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4431e9
Code: 28 c3 e8 4a 15 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd3f5d9338 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffd3f5d9348 RCX: 00000000004431e9
RDX: 0000000020000300 RSI: 00000000000089a0 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd3f5d9350
R13: 00007ffd3

Crashes (104):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-net-kasan-gce 2021/07/28 14:11 net-next 3bdc70669eb2 17d6ab15 .config log report syz C possible deadlock in register_netdev
ci-upstream-bpf-next-kasan-gce 2021/08/06 23:17 bpf-next 579345e7f219 f9e341e3 .config log report info possible deadlock in register_netdev
ci-upstream-bpf-next-kasan-gce 2021/08/06 19:46 bpf-next 579345e7f219 f9e341e3 .config log report info possible deadlock in register_netdev
ci-upstream-bpf-next-kasan-gce 2021/08/05 06:27 bpf-next 372642ea83ff 7f7bb950 .config log report info possible deadlock in register_netdev
ci-upstream-bpf-next-kasan-gce 2021/08/05 00:56 bpf-next db517c8f8556 b97d64c9 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/04 20:02 net-next c2eecaa193ff b97d64c9 .config log report info possible deadlock in register_netdev
ci-upstream-bpf-next-kasan-gce 2021/08/04 16:46 bpf-next db517c8f8556 b97d64c9 .config log report info possible deadlock in register_netdev
ci-upstream-bpf-next-kasan-gce 2021/08/04 13:18 bpf-next 83f31535565c 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/03 20:29 net-next 7cdd0a89ec70 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/03 10:56 net-next 7cdd0a89ec70 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/03 08:51 net-next 28814cd18cd7 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/03 04:48 net-next 28814cd18cd7 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/03 03:12 net-next 28814cd18cd7 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/08/02 11:04 net-next 3e12361b6d23 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/07/31 14:00 net-next 3e12361b6d23 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-net-kasan-gce 2021/07/28 10:32 net-next 3bdc70669eb2 17d6ab15 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/06 13:21 linux-next 8d4b477da1a8 f9e341e3 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/06 07:13 linux-next 8d4b477da1a8 d2d6e680 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/06 05:46 linux-next 8d4b477da1a8 d2d6e680 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/06 04:37 linux-next 8d4b477da1a8 d2d6e680 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/05 20:24 linux-next 8d4b477da1a8 d2d6e680 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/05 09:35 linux-next 8d4b477da1a8 7f7bb950 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 23:40 linux-next 8d4b477da1a8 b97d64c9 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 21:54 linux-next 8d4b477da1a8 b97d64c9 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 18:15 linux-next 8d4b477da1a8 b97d64c9 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 15:44 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 12:15 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 10:09 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 05:05 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 03:55 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 02:20 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/04 00:57 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/03 18:18 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/03 15:53 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/03 13:23 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/03 03:02 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/02 15:10 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/02 08:56 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/02 01:44 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/01 23:44 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/01 20:39 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/08/01 08:16 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/07/31 21:37 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/07/31 17:26 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/07/31 06:09 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/07/31 01:45 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/07/30 21:02 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev
ci-upstream-linux-next-kasan-gce-root 2021/07/30 19:51 linux-next 8d4b477da1a8 6c236867 .config log report info possible deadlock in register_netdev