xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING ====================================================== WARNING: possible circular locking dependency detected 4.19.112-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/25856 is trying to acquire lock: 000000004891de97 (&sig->cred_guard_mutex){+.+.}, at: do_io_accounting+0x1da/0x7b0 fs/proc/base.c:2738 but task is already holding lock: 000000006689f425 (&p->lock){+.+.}, at: seq_read+0x6b/0x10f0 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&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 -> #2 (sb_writers#4){.+.+}: sb_start_write include/linux/fs.h:1578 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_setattr+0xdd/0x950 fs/overlayfs/inode.c:30 notify_change+0xad7/0xfb0 fs/attr.c:334 chown_common+0x4a9/0x550 fs/open.c:651 do_fchownat+0x126/0x1e0 fs/open.c:681 __do_sys_chown fs/open.c:701 [inline] __se_sys_chown fs/open.c:699 [inline] __x64_sys_chown+0x77/0xb0 fs/open.c:699 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: 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 -> #0 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1300 kernel/locking/mutex.c:1072 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 other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#4 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#4); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 1 lock held by syz-executor.1/25856: #0: 000000006689f425 (&p->lock){+.+.}, at: seq_read+0x6b/0x10f0 fs/seq_file.c:161 stack backtrace: CPU: 0 PID: 25856 Comm: syz-executor.1 Not tainted 4.19.112-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 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1300 kernel/locking/mutex.c:1072 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 RIP: 0033:0x45c849 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:00007f40ef747c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f40ef7486d4 RCX: 000000000045c849 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000081 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000008d0 R14: 00000000004cb74a R15: 000000000076bf0c overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified overlayfs: unrecognized mount option "lowerdi˙=./bus" or missing value xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_check_match: 24 callbacks suppressed x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified x_tables: ip6_tables: cgroup match: used from hooks PREROUTING, but only valid from INPUT/OUTPUT/POSTROUTING xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified xt_cgroup: xt_cgroup: no path or classid specified