====================================================== WARNING: possible circular locking dependency detected 4.19.108-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/9777 is trying to acquire lock: 00000000407f3139 (&ovl_i_mutex_dir_key[depth]){++++}, at: inode_lock_shared include/linux/fs.h:757 [inline] 00000000407f3139 (&ovl_i_mutex_dir_key[depth]){++++}, at: lookup_slow+0x43/0x70 fs/namei.c:1688 but task is already holding lock: 00000000d51b37a8 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: inode_lock_shared include/linux/fs.h:757 [inline] 00000000d51b37a8 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: do_last fs/namei.c:3326 [inline] 00000000d51b37a8 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: path_openat+0x1d18/0x4200 fs/namei.c:3537 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&ovl_i_mutex_dir_key[depth]#2){.+.+}: inode_lock_shared include/linux/fs.h:757 [inline] do_last fs/namei.c:3326 [inline] path_openat+0x1d18/0x4200 fs/namei.c:3537 do_filp_open+0x1a1/0x280 fs/namei.c:3567 do_open_execat+0x124/0x5b0 fs/exec.c:853 __do_execve_file.isra.0+0x1577/0x2110 fs/exec.c:1755 do_execveat_common fs/exec.c:1866 [inline] do_execve fs/exec.c:1883 [inline] __do_sys_execve fs/exec.c:1964 [inline] __se_sys_execve fs/exec.c:1959 [inline] __x64_sys_execve+0x8a/0xb0 fs/exec.c:1959 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&sig->cred_guard_mutex){+.+.}: do_io_accounting+0x1da/0x7b0 fs/proc/base.c:2738 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4b9/0x10f0 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x46b/0x640 fs/read_write.c:925 vfs_readv+0xf0/0x160 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x478/0x970 fs/splice.c:417 do_splice_to+0x10e/0x160 fs/splice.c:881 splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959 do_splice_direct+0x1a8/0x270 fs/splice.c:1068 do_sendfile+0x549/0xc10 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1494 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&p->lock){+.+.}: seq_read+0x6b/0x10f0 fs/seq_file.c:161 proc_reg_read+0x1bd/0x280 fs/proc/inode.c:231 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x46b/0x640 fs/read_write.c:925 vfs_readv+0xf0/0x160 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x478/0x970 fs/splice.c:417 do_splice_to+0x10e/0x160 fs/splice.c:881 splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959 do_splice_direct+0x1a8/0x270 fs/splice.c:1068 do_sendfile+0x549/0xc10 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1494 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#4){.+.+}: sb_start_write include/linux/fs.h:1578 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_do_remove+0xf8/0xd70 fs/overlayfs/dir.c:843 vfs_rmdir fs/namei.c:3882 [inline] vfs_rmdir+0x194/0x460 fs/namei.c:3861 do_rmdir+0x371/0x3e0 fs/namei.c:3943 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]){++++}: down_read+0x37/0xb0 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:757 [inline] lookup_slow+0x43/0x70 fs/namei.c:1688 lookup_one_len_unlocked+0xf5/0x100 fs/namei.c:2573 ovl_lookup_single+0x60/0x920 fs/overlayfs/namei.c:206 ovl_lookup_layer+0x3c7/0x450 fs/overlayfs/namei.c:292 ovl_lookup+0xce2/0x1a00 fs/overlayfs/namei.c:903 lookup_open+0x681/0x19b0 fs/namei.c:3214 do_last fs/namei.c:3327 [inline] path_openat+0x1d30/0x4200 fs/namei.c:3537 do_filp_open+0x1a1/0x280 fs/namei.c:3567 do_open_execat+0x124/0x5b0 fs/exec.c:853 __do_execve_file.isra.0+0x1577/0x2110 fs/exec.c:1755 do_execveat_common fs/exec.c:1866 [inline] do_execve fs/exec.c:1883 [inline] __do_sys_execve fs/exec.c:1964 [inline] __se_sys_execve fs/exec.c:1959 [inline] __x64_sys_execve+0x8a/0xb0 fs/exec.c:1959 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth] --> &sig->cred_guard_mutex --> &ovl_i_mutex_dir_key[depth]#2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ovl_i_mutex_dir_key[depth]#2); lock(&sig->cred_guard_mutex); lock(&ovl_i_mutex_dir_key[depth]#2); lock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 2 locks held by syz-executor.0/9777: #0: 00000000b8fedd16 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x51/0x120 fs/exec.c:1404 #1: 00000000d51b37a8 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: inode_lock_shared include/linux/fs.h:757 [inline] #1: 00000000d51b37a8 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: do_last fs/namei.c:3326 [inline] #1: 00000000d51b37a8 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: path_openat+0x1d18/0x4200 fs/namei.c:3537 stack backtrace: CPU: 1 PID: 9777 Comm: syz-executor.0 Not tainted 4.19.108-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+0x188/0x20d lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x1c4/0x282 kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x2e19/0x49c0 kernel/locking/lockdep.c:3411 lock_acquire+0x170/0x400 kernel/locking/lockdep.c:3903 down_read+0x37/0xb0 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:757 [inline] lookup_slow+0x43/0x70 fs/namei.c:1688 lookup_one_len_unlocked+0xf5/0x100 fs/namei.c:2573 ovl_lookup_single+0x60/0x920 fs/overlayfs/namei.c:206 ovl_lookup_layer+0x3c7/0x450 fs/overlayfs/namei.c:292 ovl_lookup+0xce2/0x1a00 fs/overlayfs/namei.c:903 lookup_open+0x681/0x19b0 fs/namei.c:3214 do_last fs/namei.c:3327 [inline] path_openat+0x1d30/0x4200 fs/namei.c:3537 do_filp_open+0x1a1/0x280 fs/namei.c:3567 do_open_execat+0x124/0x5b0 fs/exec.c:853 __do_execve_file.isra.0+0x1577/0x2110 fs/exec.c:1755 do_execveat_common fs/exec.c:1866 [inline] do_execve fs/exec.c:1883 [inline] __do_sys_execve fs/exec.c:1964 [inline] __se_sys_execve fs/exec.c:1959 [inline] __x64_sys_execve+0x8a/0xb0 fs/exec.c:1959 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c4a9 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:00007f8f7f627c78 EFLAGS: 00000246 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 00007f8f7f6286d4 RCX: 000000000045c4a9 RDX: 0000000020000300 RSI: 0000000020000280 RDI: 0000000020000140 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000000a6 R14: 00000000004c2fe0 R15: 000000000076bf2c overlayfs: maximum fs stacking depth exceeded overlayfs: maximum fs stacking depth exceeded kauditd_printk_skb: 3 callbacks suppressed audit: type=1400 audit(1583712092.248:98): avc: denied { map } for pid=9839 comm="syz-executor.1" path="socket:[36703]" dev="sockfs" ino=36703 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=rawip_socket permissive=1