====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.5/2925 is trying to acquire lock: ffff888018d38630 (&u->lock/1){+.+.}-{2:2}, at: sk_diag_dump_icons net/unix/diag.c:86 [inline] ffff888018d38630 (&u->lock/1){+.+.}-{2:2}, at: sk_diag_fill+0x6f2/0x1090 net/unix/diag.c:154 but task is already holding lock: ffff888018d389a0 ( rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_dump_icons net/unix/diag.c:68 [inline] rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_fill+0x64b/0x1090 net/unix/diag.c:154 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (rlock-AF_UNIX){+.+.}-{2:2}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb3/0x100 kernel/locking/spinlock.c:159 skb_queue_tail+0x32/0x120 net/core/skbuff.c:3263 unix_dgram_sendmsg+0x1a3c/0x2a80 net/unix/af_unix.c:1850 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg net/socket.c:723 [inline] ____sys_sendmsg+0x5a2/0x900 net/socket.c:2392 ___sys_sendmsg net/socket.c:2446 [inline] __sys_sendmmsg+0x500/0x790 net/socket.c:2532 __do_sys_sendmmsg net/socket.c:2561 [inline] __se_sys_sendmmsg net/socket.c:2558 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2558 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&u->lock/1){+.+.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 _raw_spin_lock_nested+0x2d/0x40 kernel/locking/spinlock.c:361 sk_diag_dump_icons net/unix/diag.c:86 [inline] sk_diag_fill+0x6f2/0x1090 net/unix/diag.c:154 sk_diag_dump net/unix/diag.c:192 [inline] unix_diag_dump+0x2e9/0x4f0 net/unix/diag.c:220 netlink_dump+0x5b7/0xc30 net/netlink/af_netlink.c:2278 __netlink_dump_start+0x53d/0x710 net/netlink/af_netlink.c:2383 netlink_dump_start include/linux/netlink.h:258 [inline] unix_diag_handler_dump+0x307/0x7d0 net/unix/diag.c:319 __sock_diag_cmd net/core/sock_diag.c:234 [inline] sock_diag_rcv_msg+0x350/0x460 net/core/sock_diag.c:265 netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2504 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x7de/0x9b0 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x9e7/0xe00 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg net/socket.c:723 [inline] sock_write_iter+0x398/0x520 net/socket.c:1056 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:2108 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 vfs_writev fs/read_write.c:939 [inline] do_writev+0x240/0x440 fs/read_write.c:982 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/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(rlock-AF_UNIX); lock(&u->lock/1); lock(rlock-AF_UNIX); lock(&u->lock/1); *** DEADLOCK *** 5 locks held by syz-executor.5/2925: #0: ffffffff8d751a88 (sock_diag_mutex){+.+.}-{3:3}, at: sock_diag_rcv+0x17/0x40 net/core/sock_diag.c:275 #1: ffffffff8d7518e8 (sock_diag_table_mutex){+.+.}-{3:3}, at: __sock_diag_cmd net/core/sock_diag.c:229 [inline] #1: ffffffff8d7518e8 (sock_diag_table_mutex){+.+.}-{3:3}, at: sock_diag_rcv_msg+0x23f/0x460 net/core/sock_diag.c:265 #2: ffff88806de6f638 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{3:3}, at: netlink_dump+0xd0/0xc30 net/netlink/af_netlink.c:2233 #3: ffffffff8d841178 (unix_table_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] #3: ffffffff8d841178 (unix_table_lock){+.+.}-{2:2}, at: unix_diag_dump+0xf1/0x4f0 net/unix/diag.c:206 #4: ffff888018d389a0 (rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] #4: ffff888018d389a0 (rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_dump_icons net/unix/diag.c:68 [inline] #4: ffff888018d389a0 (rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_fill+0x64b/0x1090 net/unix/diag.c:154 stack backtrace: CPU: 0 PID: 2925 Comm: syz-executor.5 Not tainted 5.14.0-rc5-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+0x1ae/0x29f lib/dump_stack.c:105 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 _raw_spin_lock_nested+0x2d/0x40 kernel/locking/spinlock.c:361 sk_diag_dump_icons net/unix/diag.c:86 [inline] sk_diag_fill+0x6f2/0x1090 net/unix/diag.c:154 sk_diag_dump net/unix/diag.c:192 [inline] unix_diag_dump+0x2e9/0x4f0 net/unix/diag.c:220 netlink_dump+0x5b7/0xc30 net/netlink/af_netlink.c:2278 __netlink_dump_start+0x53d/0x710 net/netlink/af_netlink.c:2383 netlink_dump_start include/linux/netlink.h:258 [inline] unix_diag_handler_dump+0x307/0x7d0 net/unix/diag.c:319 __sock_diag_cmd net/core/sock_diag.c:234 [inline] sock_diag_rcv_msg+0x350/0x460 net/core/sock_diag.c:265 netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2504 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:276 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x7de/0x9b0 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x9e7/0xe00 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg net/socket.c:723 [inline] sock_write_iter+0x398/0x520 net/socket.c:1056 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:2108 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 vfs_writev fs/read_write.c:939 [inline] do_writev+0x240/0x440 fs/read_write.c:982 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/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:00007f5b30d9a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 0000000000000001 RSI: 00000000200000c0 RDI: 0000000000000006 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffd964833ff R14: 00007f5b30d9a300 R15: 0000000000022000