====================================================== WARNING: possible circular locking dependency detected 4.19.177-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/1578 is trying to acquire lock: 0000000032de9193 (&sig->cred_guard_mutex){+.+.}, at: do_io_accounting fs/proc/base.c:2737 [inline] 0000000032de9193 (&sig->cred_guard_mutex){+.+.}, at: proc_tid_io_accounting+0x184/0x2b0 fs/proc/base.c:2780 but task is already holding lock: 00000000aeaa0447 (&p->lock){+.+.}, at: seq_read+0x6b/0x1160 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/0x1160 fs/seq_file.c:161 proc_reg_read+0x1bd/0x2d0 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+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x457/0xa00 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+0x1a7/0x270 fs/splice.c:1068 do_sendfile+0x550/0xc30 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64+0x147/0x160 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#3){.+.+}: sb_start_write include/linux/fs.h:1579 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_create_object+0x96/0x290 fs/overlayfs/dir.c:600 lookup_open+0x893/0x1a20 fs/namei.c:3235 do_last fs/namei.c:3327 [inline] path_openat+0x1094/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_sys_open+0x3b3/0x520 fs/open.c:1085 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:758 [inline] do_last fs/namei.c:3326 [inline] path_openat+0x17ec/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_open_execat+0x11d/0x5b0 fs/exec.c:853 __do_execve_file+0x1a8b/0x2360 fs/exec.c:1770 do_execveat_common fs/exec.c:1879 [inline] do_execve+0x35/0x50 fs/exec.c:1896 __do_sys_execve fs/exec.c:1977 [inline] __se_sys_execve fs/exec.c:1972 [inline] __x64_sys_execve+0x7c/0xa0 fs/exec.c:1972 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+0xd7/0x1260 kernel/locking/mutex.c:1072 do_io_accounting fs/proc/base.c:2737 [inline] proc_tid_io_accounting+0x184/0x2b0 fs/proc/base.c:2780 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4be/0x1160 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+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 do_preadv fs/read_write.c:1071 [inline] __do_sys_preadv fs/read_write.c:1121 [inline] __se_sys_preadv fs/read_write.c:1116 [inline] __x64_sys_preadv+0x22b/0x310 fs/read_write.c:1116 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#3 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); Unknown ioctl -1056942500 lock(sb_writers#3); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 1 lock held by syz-executor.4/1578: #0: 00000000aeaa0447 (&p->lock){+.+.}, at: seq_read+0x6b/0x1160 fs/seq_file.c:161 stack backtrace: Unknown ioctl -1056942500 CPU: 1 PID: 1578 Comm: syz-executor.4 Not tainted 4.19.177-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+0x1fc/0x2ef lib/dump_stack.c:118 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1865 [inline] check_prevs_add kernel/locking/lockdep.c:1978 [inline] validate_chain kernel/locking/lockdep.c:2419 [inline] __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3415 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xd7/0x1260 kernel/locking/mutex.c:1072 do_io_accounting fs/proc/base.c:2737 [inline] proc_tid_io_accounting+0x184/0x2b0 fs/proc/base.c:2780 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4be/0x1160 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+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 do_preadv fs/read_write.c:1071 [inline] __do_sys_preadv fs/read_write.c:1121 [inline] __se_sys_preadv fs/read_write.c:1116 [inline] __x64_sys_preadv+0x22b/0x310 fs/read_write.c:1116 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x465ef9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8749e3e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465ef9 RDX: 000000000000037d RSI: 0000000020000500 RDI: 0000000000000003 RBP: 00000000004bcd1c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffdbb143abf R14: 00007f8749e3e300 R15: 0000000000022000 veth1_to_bond: mtu greater than device maximum netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'. audit: type=1800 audit(1614530513.254:7344): pid=2050 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="vcs2" dev="sda1" ino=17041 res=0 audit: type=1800 audit(1614530513.284:7345): pid=2050 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="vcs2" dev="sda1" ino=17041 res=0 audit: type=1800 audit(1614530513.434:7346): pid=2077 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="vcs2" dev="sda1" ino=17041 res=0 audit: type=1800 audit(1614530513.534:7347): pid=2090 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="vcs2" dev="sda1" ino=17041 res=0 audit: type=1800 audit(1614530516.354:7348): pid=2119 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="vcs2" dev="sda1" ino=17041 res=0