====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc3-next-20210730-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/10864 is trying to acquire lock: ffffffff8d0d9e68 (rtnl_mutex){+.+.}-{3:3}, at: br_del_bridge+0x14/0x110 net/bridge/br_if.c:470 but task is already holding lock: ffffffff8d0b7c88 (br_ioctl_mutex){+.+.}-{3:3}, at: br_ioctl_call+0x3b/0xa0 net/socket.c:1090 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:957 [inline] __mutex_lock+0x131/0x1300 kernel/locking/mutex.c:1096 br_ioctl_call+0x3b/0xa0 net/socket.c:1090 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:1129 sock_ioctl+0x2f1/0x640 net/socket.c:1232 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:866 [inline] __se_sys_ioctl fs/ioctl.c:852 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:852 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:957 [inline] __mutex_lock+0x131/0x1300 kernel/locking/mutex.c:1096 br_del_bridge+0x14/0x110 net/bridge/br_if.c:470 br_ioctl_stub+0x2f1/0x7f0 net/bridge/br_ioctl.c:392 br_ioctl_call+0x5e/0xa0 net/socket.c:1092 sock_ioctl+0x30c/0x640 net/socket.c:1186 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:866 [inline] __se_sys_ioctl fs/ioctl.c:852 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:852 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-executor.0/10864: #0: ffffffff8d0b7c88 (br_ioctl_mutex){+.+.}-{3:3}, at: br_ioctl_call+0x3b/0xa0 net/socket.c:1090 stack backtrace: CPU: 0 PID: 10864 Comm: syz-executor.0 Not tainted 5.14.0-rc3-next-20210730-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:957 [inline] __mutex_lock+0x131/0x1300 kernel/locking/mutex.c:1096 br_del_bridge+0x14/0x110 net/bridge/br_if.c:470 br_ioctl_stub+0x2f1/0x7f0 net/bridge/br_ioctl.c:392 br_ioctl_call+0x5e/0xa0 net/socket.c:1092 sock_ioctl+0x30c/0x640 net/socket.c:1186 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:866 [inline] __se_sys_ioctl fs/ioctl.c:852 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:852 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: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f356ea59188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 0000000020000300 RSI: 00000000000089a1 RDI: 0000000000000005 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffd3e50c8df R14: 00007f356ea59300 R15: 0000000000022000