====================================================== WARNING: possible circular locking dependency detected 4.17.0-rc3+ #59 Not tainted ------------------------------------------------------ syz-executor1/25282 is trying to acquire lock: 000000004fddf743 (&(&u->lock)->rlock/1){+.+.}, at: sk_diag_dump_icons net/unix/diag.c:82 [inline] 000000004fddf743 (&(&u->lock)->rlock/1){+.+.}, at: sk_diag_fill.isra.5+0xa43/0x10d0 net/unix/diag.c:144 but task is already holding lock: 00000000b6895645 (rlock-AF_UNIX){+.+.}, at: spin_lock include/linux/spinlock.h:310 [inline] 00000000b6895645 (rlock-AF_UNIX){+.+.}, at: sk_diag_dump_icons net/unix/diag.c:64 [inline] 00000000b6895645 (rlock-AF_UNIX){+.+.}, at: sk_diag_fill.isra.5+0x94e/0x10d0 net/unix/diag.c:144 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (rlock-AF_UNIX){+.+.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 skb_queue_tail+0x26/0x150 net/core/skbuff.c:2900 unix_dgram_sendmsg+0xf77/0x1730 net/unix/af_unix.c:1797 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 ___sys_sendmsg+0x525/0x940 net/socket.c:2117 __sys_sendmmsg+0x3bb/0x6f0 net/socket.c:2205 __compat_sys_sendmmsg net/compat.c:770 [inline] __do_compat_sys_sendmmsg net/compat.c:777 [inline] __se_compat_sys_sendmmsg net/compat.c:774 [inline] __ia32_compat_sys_sendmmsg+0x9f/0x100 net/compat.c:774 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline] do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 -> #0 (&(&u->lock)->rlock/1){+.+.}: lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 _raw_spin_lock_nested+0x28/0x40 kernel/locking/spinlock.c:354 sk_diag_dump_icons net/unix/diag.c:82 [inline] sk_diag_fill.isra.5+0xa43/0x10d0 net/unix/diag.c:144 sk_diag_dump net/unix/diag.c:178 [inline] unix_diag_dump+0x35f/0x550 net/unix/diag.c:206 netlink_dump+0x507/0xd20 net/netlink/af_netlink.c:2226 __netlink_dump_start+0x51a/0x780 net/netlink/af_netlink.c:2323 netlink_dump_start include/linux/netlink.h:214 [inline] unix_diag_handler_dump+0x3f4/0x7b0 net/unix/diag.c:307 __sock_diag_cmd net/core/sock_diag.c:230 [inline] sock_diag_rcv_msg+0x2e0/0x3d0 net/core/sock_diag.c:261 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2448 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:272 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] netlink_unicast+0x58b/0x740 net/netlink/af_netlink.c:1336 netlink_sendmsg+0x9f0/0xfa0 net/netlink/af_netlink.c:1901 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 sock_write_iter+0x35a/0x5a0 net/socket.c:908 call_write_iter include/linux/fs.h:1784 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x64d/0x960 fs/read_write.c:487 vfs_write+0x1f8/0x560 fs/read_write.c:549 ksys_write+0xf9/0x250 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __ia32_sys_write+0x71/0xb0 fs/read_write.c:607 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline] do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rlock-AF_UNIX); lock(&(&u->lock)->rlock/1); lock(rlock-AF_UNIX); lock(&(&u->lock)->rlock/1); *** DEADLOCK *** 5 locks held by syz-executor1/25282: #0: 000000003919e1bd (sock_diag_mutex){+.+.}, at: sock_diag_rcv+0x1b/0x40 net/core/sock_diag.c:271 #1: 000000004f328d3e (sock_diag_table_mutex){+.+.}, at: __sock_diag_cmd net/core/sock_diag.c:225 [inline] #1: 000000004f328d3e (sock_diag_table_mutex){+.+.}, at: sock_diag_rcv_msg+0x169/0x3d0 net/core/sock_diag.c:261 #2: 000000004cc04dbb (nlk_cb_mutex-SOCK_DIAG){+.+.}, at: netlink_dump+0x98/0xd20 net/netlink/af_netlink.c:2182 #3: 00000000accdef41 (unix_table_lock){+.+.}, at: spin_lock include/linux/spinlock.h:310 [inline] #3: 00000000accdef41 (unix_table_lock){+.+.}, at: unix_diag_dump+0x10a/0x550 net/unix/diag.c:192 #4: 00000000b6895645 (rlock-AF_UNIX){+.+.}, at: spin_lock include/linux/spinlock.h:310 [inline] #4: 00000000b6895645 (rlock-AF_UNIX){+.+.}, at: sk_diag_dump_icons net/unix/diag.c:64 [inline] #4: 00000000b6895645 (rlock-AF_UNIX){+.+.}, at: sk_diag_fill.isra.5+0x94e/0x10d0 net/unix/diag.c:144 stack backtrace: CPU: 1 PID: 25282 Comm: syz-executor1 Not tainted 4.17.0-rc3+ #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_circular_bug.isra.36.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1223 check_prev_add kernel/locking/lockdep.c:1863 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2417 [inline] __lock_acquire+0x343e/0x5140 kernel/locking/lockdep.c:3431 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 _raw_spin_lock_nested+0x28/0x40 kernel/locking/spinlock.c:354 sk_diag_dump_icons net/unix/diag.c:82 [inline] sk_diag_fill.isra.5+0xa43/0x10d0 net/unix/diag.c:144 sk_diag_dump net/unix/diag.c:178 [inline] unix_diag_dump+0x35f/0x550 net/unix/diag.c:206 netlink_dump+0x507/0xd20 net/netlink/af_netlink.c:2226 __netlink_dump_start+0x51a/0x780 net/netlink/af_netlink.c:2323 netlink_dump_start include/linux/netlink.h:214 [inline] unix_diag_handler_dump+0x3f4/0x7b0 net/unix/diag.c:307 __sock_diag_cmd net/core/sock_diag.c:230 [inline] sock_diag_rcv_msg+0x2e0/0x3d0 net/core/sock_diag.c:261 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2448 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:272 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] netlink_unicast+0x58b/0x740 net/netlink/af_netlink.c:1336 netlink_sendmsg+0x9f0/0xfa0 net/netlink/af_netlink.c:1901 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 sock_write_iter+0x35a/0x5a0 net/socket.c:908 call_write_iter include/linux/fs.h:1784 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x64d/0x960 fs/read_write.c:487 vfs_write+0x1f8/0x560 fs/read_write.c:549 ksys_write+0xf9/0x250 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __ia32_sys_write+0x71/0xb0 fs/read_write.c:607 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline] do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f8ccb9 RSP: 002b:00000000f5f880ac EFLAGS: 00000282 ORIG_RAX: 0000000000000004 RAX: ffffffffffffffda RBX: 0000000000000017 RCX: 000000002058bfe4 RDX: 0000000000000029 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000