======================================================
WARNING: possible circular locking dependency detected
4.14.215-syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:3/2845 is trying to acquire lock:
 (sk_lock-AF_INET){+.+.}, at: [<ffffffff869dfafe>] do_strp_work net/strparser/strparser.c:415 [inline]
 (sk_lock-AF_INET){+.+.}, at: [<ffffffff869dfafe>] strp_work+0x3e/0x100 net/strparser/strparser.c:434

but task is already holding lock:
 ((&strp->work)){+.+.}, at: [<ffffffff81373836>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 ((&strp->work)){+.+.}:
       flush_work+0xad/0x770 kernel/workqueue.c:2889
       __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2964
       strp_done+0x53/0xd0 net/strparser/strparser.c:519
       kcm_attach net/kcm/kcmsock.c:1429 [inline]
       kcm_attach_ioctl net/kcm/kcmsock.c:1490 [inline]
       kcm_ioctl+0x828/0xfb0 net/kcm/kcmsock.c:1701
       sock_do_ioctl net/socket.c:974 [inline]
       sock_ioctl+0x2cc/0x4c0 net/socket.c:1071
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:500 [inline]
       do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
       SYSC_ioctl fs/ioctl.c:701 [inline]
       SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

-> #0 (sk_lock-AF_INET){+.+.}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       lock_sock_nested+0xb7/0x100 net/core/sock.c:2796
       do_strp_work net/strparser/strparser.c:415 [inline]
       strp_work+0x3e/0x100 net/strparser/strparser.c:434
       process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
       worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
       kthread+0x30d/0x420 kernel/kthread.c:232
       ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((&strp->work));
                               lock(sk_lock-AF_INET);
                               lock((&strp->work));
  lock(sk_lock-AF_INET);

 *** DEADLOCK ***

2 locks held by kworker/u4:3/2845:
 #0:  ("%s""kstrp"){+.+.}, at: [<ffffffff81373800>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087
 #1:  ((&strp->work)){+.+.}, at: [<ffffffff81373836>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091

stack backtrace:
CPU: 0 PID: 2845 Comm: kworker/u4:3 Not tainted 4.14.215-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kstrp strp_work
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 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
 lock_sock_nested+0xb7/0x100 net/core/sock.c:2796
 do_strp_work net/strparser/strparser.c:415 [inline]
 strp_work+0x3e/0x100 net/strparser/strparser.c:434
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
IPv6: addrconf: prefix option has invalid lifetime
audit: type=1804 audit(1610887543.980:34): pid=14509 uid=0 auid=0 ses=4 op="invalid_pcr" cause="open_writers" comm="syz-executor.2" name="/root/syzkaller-testdir864142658/syzkaller.vcASjC/129/bus" dev="sda1" ino=16276 res=1
audit: type=1804 audit(1610887544.020:35): pid=14509 uid=0 auid=0 ses=4 op="invalid_pcr" cause="ToMToU" comm="syz-executor.2" name="/root/syzkaller-testdir864142658/syzkaller.vcASjC/129/bus" dev="sda1" ino=16276 res=1
audit: type=1804 audit(1610887544.020:36): pid=14509 uid=0 auid=0 ses=4 op="invalid_pcr" cause="ToMToU" comm="syz-executor.2" name="/root/syzkaller-testdir864142658/syzkaller.vcASjC/129/bus" dev="sda1" ino=16276 res=1
audit: type=1804 audit(1610887544.100:37): pid=14517 uid=0 auid=0 ses=4 op="invalid_pcr" cause="ToMToU" comm="syz-executor.2" name="/root/syzkaller-testdir864142658/syzkaller.vcASjC/129/bus" dev="sda1" ino=16276 res=1
audit: type=1804 audit(1610887544.240:38): pid=14517 uid=0 auid=0 ses=4 op="invalid_pcr" cause="open_writers" comm="syz-executor.2" name="/root/syzkaller-testdir864142658/syzkaller.vcASjC/129/bus" dev="sda1" ino=16276 res=1
audit: type=1804 audit(1610887544.240:39): pid=14509 uid=0 auid=0 ses=4 op="invalid_pcr" cause="ToMToU" comm="syz-executor.2" name="/root/syzkaller-testdir864142658/syzkaller.vcASjC/129/bus" dev="sda1" ino=16276 res=1
FAT-fs (loop4): bogus number of reserved sectors
FAT-fs (loop4): Can't find a valid FAT filesystem
FAT-fs (loop4): bogus number of reserved sectors
FAT-fs (loop4): Can't find a valid FAT filesystem
Cannot find del_set index 0 as target
Cannot find del_set index 0 as target
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
EXT4-fs (loop5): ext4_check_descriptors: Checksum for group 0 failed (57356!=0)
EXT4-fs error (device loop5): ext4_fill_super:4365: inode #2: comm syz-executor.5: iget: bogus i_mode (0)
EXT4-fs (loop5): get root inode failed
EXT4-fs (loop5): mount failed
print_req_error: I/O error, dev loop5, sector 0
Buffer I/O error on dev loop5, logical block 0, async page read
print_req_error: I/O error, dev loop5, sector 6
Buffer I/O error on dev loop5, logical block 3, async page read
EXT4-fs (loop5): ext4_check_descriptors: Checksum for group 0 failed (57356!=0)
EXT4-fs error (device loop5): ext4_fill_super:4365: inode #2: comm syz-executor.5: iget: bogus i_mode (0)
EXT4-fs (loop5): get root inode failed
EXT4-fs (loop5): mount failed
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
Process accounting resumed
Process accounting resumed
Process accounting resumed
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
Process accounting resumed
Process accounting resumed
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
audit: type=1800 audit(1610887550.333:40): pid=15079 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
Process accounting resumed
audit: type=1800 audit(1610887550.373:41): pid=15079 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
Process accounting resumed
Process accounting resumed
audit: type=1800 audit(1610887550.463:42): pid=15096 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16342 res=0
audit: type=1800 audit(1610887550.463:43): pid=15092 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16342 res=0
audit: type=1800 audit(1610887550.543:44): pid=15108 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.
audit: type=1800 audit(1610887550.553:45): pid=15108 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
block nbd4: Receive control failed (result -107)
block nbd4: shutting down sockets
block nbd4: Receive control failed (result -107)
audit: type=1800 audit(1610887550.823:46): pid=15161 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
block nbd4: Device being setup by another task
audit: type=1800 audit(1610887550.863:47): pid=15161 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
block nbd2: Receive control failed (result -107)
block nbd2: shutting down sockets
block nbd4: Device being setup by another task
block nbd4: Device being setup by another task
block nbd2: Receive control failed (result -107)
block nbd2: shutting down sockets
audit: type=1800 audit(1610887551.723:48): pid=15222 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
block nbd4: Device being setup by another task
block nbd2: Receive control failed (result -107)
block nbd2: shutting down sockets
audit: type=1800 audit(1610887551.783:49): pid=15222 uid=0 auid=0 ses=4 op="collect_data" cause="failed(directio)" comm="syz-executor.1" name="bus" dev="sda1" ino=16356 res=0
block nbd4: Device being setup by another task
nla_parse: 19 callbacks suppressed
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.1'.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.1'.
overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'.