======================================================
WARNING: possible circular locking dependency detected
4.19.211-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/28413 is trying to acquire lock:
00000000d952acfe (&sig->cred_guard_mutex){+.+.}, at: lock_trace fs/proc/base.c:402 [inline]
00000000d952acfe (&sig->cred_guard_mutex){+.+.}, at: proc_pid_syscall+0xb8/0x2f0 fs/proc/base.c:635

but task is already holding lock:
0000000018bed185 (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&p->lock){+.+.}:
       seq_read+0x6b/0x11c0 fs/seq_file.c:164
       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:602
       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:937 [inline]
       __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078
       lock_trace fs/proc/base.c:402 [inline]
       proc_pid_syscall+0xb8/0x2f0 fs/proc/base.c:635
       proc_single_show+0xeb/0x170 fs/proc/base.c:755
       seq_read+0x4e0/0x11c0 fs/seq_file.c:232
       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);
                               lock(sb_writers#3);
                               lock(&p->lock);
  lock(&sig->cred_guard_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor.4/28413:
 #0: 0000000018bed185 (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164

stack backtrace:
CPU: 1 PID: 28413 Comm: syz-executor.4 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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:1222
 check_prev_add kernel/locking/lockdep.c:1866 [inline]
 check_prevs_add kernel/locking/lockdep.c:1979 [inline]
 validate_chain kernel/locking/lockdep.c:2420 [inline]
 __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908
 __mutex_lock_common kernel/locking/mutex.c:937 [inline]
 __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078
 lock_trace fs/proc/base.c:402 [inline]
 proc_pid_syscall+0xb8/0x2f0 fs/proc/base.c:635
 proc_single_show+0xeb/0x170 fs/proc/base.c:755
 seq_read+0x4e0/0x11c0 fs/seq_file.c:232
 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: 0033:0x7f638041e209
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f637ed93168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007f6380530f60 RCX: 00007f638041e209
RDX: 00000000000001d0 RSI: 00000000200017c0 RDI: 0000000000000003
RBP: 00007f6380478161 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd54e454ff R14: 00007f637ed93300 R15: 0000000000022000
audit: type=1800 audit(1659583395.747:9211): pid=28426 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.5" name="bus" dev="sda1" ino=14578 res=0
netlink: 112 bytes leftover after parsing attributes in process `syz-executor.2'.
A link change request failed with some changes committed already. Interface ipip1 may have been left with an inconsistent configuration, please check.
audit: type=1800 audit(1659583396.417:9212): pid=28431 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="bus" dev="sda1" ino=14257 res=0
kauditd_printk_skb: 4 callbacks suppressed
audit: type=1804 audit(1659583397.457:9217): pid=28573 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.4" name="/root/syzkaller-testdir3779096424/syzkaller.KJVWN7/1148/bus" dev="sda1" ino=14617 res=1
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
audit: type=1800 audit(1659583397.527:9218): pid=28529 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.5" name="bus" dev="sda1" ino=14614 res=0
IPVS: ftp: loaded support on port[0] = 21
FAT-fs (loop2): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
FAT-fs (loop2): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
audit: type=1804 audit(1659583398.267:9219): pid=28622 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/309/bus" dev="sda1" ino=14607 res=1
audit: type=1804 audit(1659583398.477:9220): pid=28658 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir2671142007/syzkaller.NHbBM6/2593/bus" dev="sda1" ino=14635 res=1
audit: type=1804 audit(1659583398.587:9221): pid=28669 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/310/bus" dev="sda1" ino=13870 res=1
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
IPVS: ftp: loaded support on port[0] = 21
audit: type=1804 audit(1659583398.627:9222): pid=28669 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/310/bus" dev="sda1" ino=13870 res=1
audit: type=1804 audit(1659583398.627:9223): pid=28669 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/310/bus" dev="sda1" ino=13870 res=1
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
audit: type=1804 audit(1659583398.637:9224): pid=28675 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.4" name="/root/syzkaller-testdir3779096424/syzkaller.KJVWN7/1149/bus" dev="sda1" ino=14622 res=1
audit: type=1804 audit(1659583399.027:9225): pid=28731 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.4" name="/root/syzkaller-testdir3779096424/syzkaller.KJVWN7/1149/bus" dev="sda1" ino=14622 res=1
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
audit: type=1804 audit(1659583399.097:9226): pid=28740 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/311/bus" dev="sda1" ino=14641 res=1
FAT-fs (loop2): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
FAT-fs (loop2): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
FAT-fs (loop2): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
FAT-fs (loop2): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
kauditd_printk_skb: 33 callbacks suppressed
audit: type=1804 audit(1659583402.477:9260): pid=29014 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.0" name="/root/syzkaller-testdir4059758111/syzkaller.VDefPq/1360/bus" dev="sda1" ino=14674 res=1
audit: type=1804 audit(1659583402.477:9261): pid=29013 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/319/bus" dev="sda1" ino=14522 res=1
netlink: 56 bytes leftover after parsing attributes in process `syz-executor.2'.
netlink: 56 bytes leftover after parsing attributes in process `syz-executor.2'.
audit: type=1804 audit(1659583402.527:9262): pid=29011 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir2671142007/syzkaller.NHbBM6/2598/bus" dev="sda1" ino=14677 res=1
audit: type=1804 audit(1659583402.607:9263): pid=29025 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/320/bus" dev="sda1" ino=14522 res=1
netlink: 56 bytes leftover after parsing attributes in process `syz-executor.2'.
audit: type=1804 audit(1659583402.627:9264): pid=29024 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.0" name="/root/syzkaller-testdir4059758111/syzkaller.VDefPq/1361/bus" dev="sda1" ino=14614 res=1
audit: type=1804 audit(1659583402.687:9265): pid=29028 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.4" name="/root/syzkaller-testdir3779096424/syzkaller.KJVWN7/1159/bus" dev="sda1" ino=14678 res=1
audit: type=1804 audit(1659583402.707:9266): pid=29034 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir2671142007/syzkaller.NHbBM6/2599/bus" dev="sda1" ino=14628 res=1
audit: type=1804 audit(1659583402.747:9267): pid=29037 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir3966375017/syzkaller.0ls67y/321/bus" dev="sda1" ino=14649 res=1
audit: type=1804 audit(1659583402.927:9268): pid=29054 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.4" name="/root/syzkaller-testdir3779096424/syzkaller.KJVWN7/1160/bus" dev="sda1" ino=14612 res=1
audit: type=1804 audit(1659583402.927:9269): pid=29051 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir2671142007/syzkaller.NHbBM6/2600/bus" dev="sda1" ino=14628 res=1