[syzbot] possible deadlock in register_netdev
From: syzbot
Date: Sun Aug 01 2021 - 06:44:29 EST
Hello,
syzbot found the following issue on:
HEAD commit: 3bdc70669eb2 Merge branch 'devlink-register'
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14e77662300000
kernel config: https://syzkaller.appspot.com/x/.config?x=914a8107c0ffdc14
dashboard link: https://syzkaller.appspot.com/bug?extid=ed8813d241a91de15965
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15581d46300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15bae1b2300000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ed8813d241a91de15965@xxxxxxxxxxxxxxxxxxxxxxxxx
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
---
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