====================================================== WARNING: possible circular locking dependency detected 6.1.89-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/10657 is trying to acquire lock: ffff88807bd31e80 (&u->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88807bd31e80 (&u->lock){+.+.}-{2:2}, at: unix_gc+0x441/0x13d0 net/unix/garbage.c:263 but task is already holding lock: ffffffff8e397ab8 (unix_gc_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffffffff8e397ab8 (unix_gc_lock){+.+.}-{2:2}, at: unix_gc+0x115/0x13d0 net/unix/garbage.c:215 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (unix_gc_lock){+.+.}-{2:2}: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] unix_notinflight+0x20a/0x380 net/unix/scm.c:73 unix_detach_fds net/unix/scm.c:136 [inline] unix_destruct_scm+0x21d/0x350 net/unix/scm.c:147 skb_release_head_state+0xf9/0x230 net/core/skbuff.c:843 skb_release_all net/core/skbuff.c:854 [inline] __kfree_skb net/core/skbuff.c:870 [inline] kfree_skb_reason+0x13d/0x390 net/core/skbuff.c:893 kfree_skb include/linux/skbuff.h:1220 [inline] manage_oob net/unix/af_unix.c:2684 [inline] unix_stream_read_generic+0xf91/0x2250 net/unix/af_unix.c:2761 unix_stream_recvmsg+0x222/0x2b0 net/unix/af_unix.c:2956 ____sys_recvmsg+0x285/0x530 ___sys_recvmsg net/socket.c:2775 [inline] __sys_recvmsg+0x2e9/0x3d0 net/socket.c:2805 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&u->lock){+.+.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] unix_gc+0x441/0x13d0 net/unix/garbage.c:263 unix_release_sock+0xab8/0xcf0 net/unix/af_unix.c:669 unix_release+0x88/0xc0 net/unix/af_unix.c:1039 __sock_release net/socket.c:654 [inline] sock_close+0xcd/0x230 net/socket.c:1400 __fput+0x3b7/0x890 fs/file_table.c:320 task_work_run+0x246/0x300 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(unix_gc_lock); lock(&u->lock); lock(unix_gc_lock); lock(&u->lock); *** DEADLOCK *** 2 locks held by syz-executor.4/10657: #0: ffff888058bc6210 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline] #0: ffff888058bc6210 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release net/socket.c:653 [inline] #0: ffff888058bc6210 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: sock_close+0x98/0x230 net/socket.c:1400 #1: ffffffff8e397ab8 (unix_gc_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #1: ffffffff8e397ab8 (unix_gc_lock){+.+.}-{2:2}, at: unix_gc+0x115/0x13d0 net/unix/garbage.c:215 stack backtrace: CPU: 0 PID: 10657 Comm: syz-executor.4 Not tainted 6.1.89-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] unix_gc+0x441/0x13d0 net/unix/garbage.c:263 unix_release_sock+0xab8/0xcf0 net/unix/af_unix.c:669 unix_release+0x88/0xc0 net/unix/af_unix.c:1039 __sock_release net/socket.c:654 [inline] sock_close+0xcd/0x230 net/socket.c:1400 __fput+0x3b7/0x890 fs/file_table.c:320 task_work_run+0x246/0x300 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f8c2967dea9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8c2a47c0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f8c297abf80 RCX: 00007f8c2967dea9 RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 000000000000000a RBP: 00007f8c296ca4a4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f8c297abf80 R15: 00007ffe0ac61468