overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on '.' does not support file handles, falling back to index=off. overlayfs: 'file0' not a directory overlayfs: filesystem on './bus' not supported as upperdir ====================================================== WARNING: possible circular locking dependency detected 4.14.228-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.3/26479 is trying to acquire lock: (&ovl_i_mutex_dir_key[depth]#2){++++}, at: [] inode_lock_shared include/linux/fs.h:729 [inline] (&ovl_i_mutex_dir_key[depth]#2){++++}, at: [] do_last fs/namei.c:3333 [inline] (&ovl_i_mutex_dir_key[depth]#2){++++}, at: [] path_openat+0x149b/0x2970 fs/namei.c:3569 but task is already holding lock: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds fs/exec.c:1404 [inline] (&sig->cred_guard_mutex){+.+.}, at: [] do_execveat_common+0x319/0x1f30 fs/exec.c:1748 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:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 lock_trace fs/proc/base.c:407 [inline] proc_pid_syscall+0xa7/0x2a0 fs/proc/base.c:639 proc_single_show+0xe7/0x150 fs/proc/base.c:761 seq_read+0x4cf/0x1120 fs/seq_file.c:237 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3eb/0x5b0 fs/read_write.c:919 vfs_readv+0xc8/0x120 fs/read_write.c:981 do_preadv fs/read_write.c:1065 [inline] SYSC_preadv fs/read_write.c:1115 [inline] SyS_preadv+0x15a/0x200 fs/read_write.c:1110 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 seq_read+0xba/0x1120 fs/seq_file.c:165 proc_reg_read+0xee/0x1a0 fs/proc/inode.c:217 do_loop_readv_writev fs/read_write.c:695 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_read+0x3eb/0x5b0 fs/read_write.c:919 vfs_readv+0xc8/0x120 fs/read_write.c:981 kernel_readv fs/splice.c:361 [inline] default_file_splice_read+0x418/0x910 fs/splice.c:416 do_splice_to+0xfb/0x140 fs/splice.c:880 splice_direct_to_actor+0x207/0x730 fs/splice.c:952 do_splice_direct+0x164/0x210 fs/splice.c:1061 do_sendfile+0x47f/0xb30 fs/read_write.c:1441 SYSC_sendfile64 fs/read_write.c:1502 [inline] SyS_sendfile64+0xff/0x110 fs/read_write.c:1488 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #2 (sb_writers#3){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x64/0x260 fs/super.c:1342 sb_start_write include/linux/fs.h:1549 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 ovl_do_remove+0x67/0xb90 fs/overlayfs/dir.c:759 vfs_rmdir.part.0+0x144/0x390 fs/namei.c:3908 vfs_rmdir fs/namei.c:3893 [inline] do_rmdir+0x334/0x3c0 fs/namei.c:3968 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: down_read+0x36/0x80 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:729 [inline] lookup_slow+0x129/0x400 fs/namei.c:1674 lookup_one_len_unlocked+0x3a0/0x410 fs/namei.c:2595 ovl_lookup_single+0x33/0x6d0 fs/overlayfs/namei.c:208 ovl_lookup_layer+0x2ef/0x3d0 fs/overlayfs/namei.c:265 ovl_lookup+0x5d9/0x1120 fs/overlayfs/namei.c:670 lookup_slow+0x20a/0x400 fs/namei.c:1696 walk_component+0x6a1/0xbc0 fs/namei.c:1825 link_path_walk+0x823/0x10a0 fs/namei.c:2154 path_lookupat+0xcb/0x780 fs/namei.c:2342 filename_lookup+0x18a/0x510 fs/namei.c:2377 user_path_at include/linux/namei.h:57 [inline] do_sys_truncate.part.0+0x78/0xf0 fs/open.c:141 do_sys_truncate fs/open.c:137 [inline] SYSC_truncate fs/open.c:155 [inline] SyS_truncate+0x23/0x40 fs/open.c:153 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 down_read+0x36/0x80 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:729 [inline] do_last fs/namei.c:3333 [inline] path_openat+0x149b/0x2970 fs/namei.c:3569 do_filp_open+0x179/0x3c0 fs/namei.c:3603 do_open_execat+0xd3/0x450 fs/exec.c:849 do_execveat_common+0x711/0x1f30 fs/exec.c:1755 do_execve fs/exec.c:1860 [inline] SYSC_execve fs/exec.c:1941 [inline] SyS_execve+0x3b/0x50 fs/exec.c:1936 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb 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 *** 1 lock held by syz-executor.3/26479: #0: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds fs/exec.c:1404 [inline] #0: (&sig->cred_guard_mutex){+.+.}, at: [] do_execveat_common+0x319/0x1f30 fs/exec.c:1748 stack backtrace: CPU: 0 PID: 26479 Comm: syz-executor.3 Not tainted 4.14.228-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 down_read+0x36/0x80 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:729 [inline] do_last fs/namei.c:3333 [inline] path_openat+0x149b/0x2970 fs/namei.c:3569 do_filp_open+0x179/0x3c0 fs/namei.c:3603 do_open_execat+0xd3/0x450 fs/exec.c:849 do_execveat_common+0x711/0x1f30 fs/exec.c:1755 do_execve fs/exec.c:1860 [inline] SYSC_execve fs/exec.c:1941 [inline] SyS_execve+0x3b/0x50 fs/exec.c:1936 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x466459 RSP: 002b:00007f4e441e3188 EFLAGS: 00000246 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459 RDX: 00000000200008c0 RSI: 0000000020000600 RDI: 00000000200004c0 RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffc5f85113f R14: 00007f4e441e3300 R15: 0000000000022000 sd 0:0:1:0: [sg0] tag#3237 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK sd 0:0:1:0: [sg0] tag#3237 CDB: Test Unit Ready sd 0:0:1:0: [sg0] tag#3237 CDB[00]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[10]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[20]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[30]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[40]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[50]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[60]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[70]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[80]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[90]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[a0]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[b0]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 sd 0:0:1:0: [sg0] tag#3237 CDB[c0]: 00 00 00 00 00 00 00 00 x_tables: ip_tables: CLASSIFY target: used from hooks PREROUTING, but only usable from FORWARD/OUTPUT/POSTROUTING netlink: 196 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 4 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 124 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 16 bytes leftover after parsing attributes in process `syz-executor.3'.