====================================================== WARNING: possible circular locking dependency detected 5.4.0-next-20191204-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.3/12028 is trying to acquire lock: ffff888039c37690 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: inode_lock_shared include/linux/fs.h:801 [inline] ffff888039c37690 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: lookup_slow+0x4a/0x80 fs/namei.c:1681 but task is already holding lock: ffff88808e7c06d0 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0xeaa/0x2c70 kernel/events/core.c:11257 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1106 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1136 lock_trace+0x4a/0xe0 fs/proc/base.c:406 proc_pid_stack+0xbf/0x200 fs/proc/base.c:450 proc_single_show+0xfd/0x1c0 fs/proc/base.c:756 seq_read+0x4ca/0x1170 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 do_preadv+0x1c4/0x280 fs/read_write.c:1089 __do_sys_preadv fs/read_write.c:1139 [inline] __se_sys_preadv fs/read_write.c:1134 [inline] __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1134 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1106 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1121 seq_read+0x71/0x1170 fs/seq_file.c:161 kernfs_fop_read+0xed/0x590 fs/kernfs/file.c:251 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x4fb/0xa20 fs/splice.c:422 do_splice_to+0x127/0x180 fs/splice.c:890 splice_direct_to_actor+0x320/0xa30 fs/splice.c:969 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#3){.+.+}: percpu_down_read include/linux/percpu-rwsem.h:40 [inline] __sb_start_write+0x241/0x460 fs/super.c:1672 sb_start_write include/linux/fs.h:1650 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:354 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:21 ovl_xattr_set+0x53/0x5b0 fs/overlayfs/inode.c:329 ovl_posix_acl_xattr_set+0x375/0xa50 fs/overlayfs/super.c:910 __vfs_setxattr+0x11f/0x180 fs/xattr.c:150 __vfs_setxattr_noperm+0x11c/0x410 fs/xattr.c:181 vfs_setxattr+0xda/0x100 fs/xattr.c:224 setxattr+0x26f/0x380 fs/xattr.c:451 path_setxattr+0x197/0x1b0 fs/xattr.c:470 __do_sys_setxattr fs/xattr.c:485 [inline] __se_sys_setxattr fs/xattr.c:481 [inline] __x64_sys_setxattr+0xc4/0x150 fs/xattr.c:481 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: down_write_killable+0x96/0x170 kernel/locking/rwsem.c:1545 iterate_dir+0x414/0x5e0 fs/readdir.c:57 ovl_dir_read fs/overlayfs/readdir.c:309 [inline] ovl_dir_read_merged+0x199/0x500 fs/overlayfs/readdir.c:374 ovl_cache_get fs/overlayfs/readdir.c:426 [inline] ovl_iterate+0x750/0xc50 fs/overlayfs/readdir.c:752 iterate_dir+0x208/0x5e0 fs/readdir.c:67 ksys_getdents64+0x1ce/0x320 fs/readdir.c:372 __do_sys_getdents64 fs/readdir.c:391 [inline] __se_sys_getdents64 fs/readdir.c:388 [inline] __x64_sys_getdents64+0x73/0xb0 fs/readdir.c:388 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}: check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 down_read+0x95/0x430 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1681 walk_component+0x747/0x1df0 fs/namei.c:1802 lookup_last fs/namei.c:2260 [inline] path_lookupat.isra.0+0x1f5/0x8d0 fs/namei.c:2305 filename_lookup+0x1b0/0x3f0 fs/namei.c:2335 kern_path+0x36/0x40 fs/namei.c:2421 create_local_trace_uprobe+0x87/0x4a0 kernel/trace/trace_uprobe.c:1547 perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:9162 perf_try_init_event+0x135/0x590 kernel/events/core.c:10462 perf_init_event kernel/events/core.c:10514 [inline] perf_event_alloc.part.0+0x158f/0x3710 kernel/events/core.c:10794 perf_event_alloc kernel/events/core.c:10676 [inline] __do_sys_perf_event_open+0x6f8/0x2c70 kernel/events/core.c:11277 __se_sys_perf_event_open kernel/events/core.c:11151 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:11151 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth]#2 --> &p->lock --> &sig->cred_guard_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->cred_guard_mutex); lock(&p->lock); lock(&sig->cred_guard_mutex); lock(&ovl_i_mutex_dir_key[depth]#2); *** DEADLOCK *** 2 locks held by syz-executor.3/12028: #0: ffff88808e7c06d0 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0xeaa/0x2c70 kernel/events/core.c:11257 #1: ffffffff8b647028 (&pmus_srcu){....}, at: perf_event_alloc.part.0+0xefc/0x3710 kernel/events/core.c:10790 stack backtrace: CPU: 0 PID: 12028 Comm: syz-executor.3 Not tainted 5.4.0-next-20191204-syzkaller #0 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+0x197/0x210 lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809 check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 down_read+0x95/0x430 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1681 walk_component+0x747/0x1df0 fs/namei.c:1802 lookup_last fs/namei.c:2260 [inline] path_lookupat.isra.0+0x1f5/0x8d0 fs/namei.c:2305 filename_lookup+0x1b0/0x3f0 fs/namei.c:2335 kern_path+0x36/0x40 fs/namei.c:2421 create_local_trace_uprobe+0x87/0x4a0 kernel/trace/trace_uprobe.c:1547 perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:9162 perf_try_init_event+0x135/0x590 kernel/events/core.c:10462 perf_init_event kernel/events/core.c:10514 [inline] perf_event_alloc.part.0+0x158f/0x3710 kernel/events/core.c:10794 perf_event_alloc kernel/events/core.c:10676 [inline] __do_sys_perf_event_open+0x6f8/0x2c70 kernel/events/core.c:11277 __se_sys_perf_event_open kernel/events/core.c:11151 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:11151 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a679 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f72f8ed8c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045a679 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f72f8ed96d4 R13: 00000000004c84e1 R14: 00000000004df940 R15: 00000000ffffffff