WARNING in fuse_destroy_inode

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: da5322e65940 Merge tag 'selinux-pr-20181115' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a5bb0b400000
kernel config: https://syzkaller.appspot.com/x/.config?x=d86f24333880b605
dashboard link: https://syzkaller.appspot.com/bug?extid=b9c89b84423073226299
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157b5f7b400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12ac8ed5400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b9c89b...@syzkaller.appspotmail.com

audit: type=1800 audit(1542387310.926:30): pid=5882 uid=0 auid=4294967295
ses=4294967295 subj==unconfined op=collect_data cause=failed(directio)
comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0
sshd (6020) used greatest stack depth: 15744 bytes left
IPVS: ftp: loaded support on port[0] = 21
WARNING: CPU: 0 PID: 6039 at fs/fuse/inode.c:119
fuse_destroy_inode+0x251/0x2c0 fs/fuse/inode.c:119
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 6039 Comm: syz-executor459 Not tainted 4.20.0-rc2+ #337
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+0x244/0x39d lib/dump_stack.c:113
panic+0x2ad/0x55c kernel/panic.c:188
__warn.cold.8+0x20/0x45 kernel/panic.c:540
report_bug+0x254/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969
RIP: 0010:fuse_destroy_inode+0x251/0x2c0 fs/fuse/inode.c:119
Code: 41 c6 44 15 00 f8 0f 84 8c fe ff ff e8 c8 f2 f2 fe 0f 0b e9 80 fe ff
ff 48 89 df e8 b9 3f 36 ff e9 50 fe ff ff e8 af f2 f2 fe <0f> 0b e9 6a ff
ff ff e8 e3 3f 36 ff e9 90 fe ff ff e8 29 5a bc fe
RSP: 0018:ffff8881c0b76818 EFLAGS: 00010293
RAX: ffff8881c435c700 RBX: ffff8881b19bb5c0 RCX: 1ffff1103816ed08
RDX: 0000000000000000 RSI: ffffffff828c9531 RDI: 0000000000000003
RBP: ffff8881c0b768e8 R08: ffff8881c435c700 R09: 0000000000000008
R10: 0000000000000002 R11: ffff8881c435c700 R12: 1ffff1103816ed04
R13: 1ffff1103816ed08 R14: ffff8881c0b768c0 R15: ffff8881b19bb998
destroy_inode+0x159/0x200 fs/inode.c:267
evict+0x5e0/0x980 fs/inode.c:575
iput_final fs/inode.c:1547 [inline]
iput+0x679/0xa90 fs/inode.c:1573
dentry_unlink_inode+0x461/0x5e0 fs/dcache.c:360
__dentry_kill+0x44c/0x7a0 fs/dcache.c:552
dentry_kill+0xc9/0x680 fs/dcache.c:671
dput.part.25+0x660/0x860 fs/dcache.c:832
dput fs/dcache.c:815 [inline]
do_one_tree+0x37/0x40 fs/dcache.c:1515
shrink_dcache_for_umount+0xc7/0x2b0 fs/dcache.c:1529
generic_shutdown_super+0xd5/0x530 fs/super.c:441
kill_anon_super+0x3e/0x60 fs/super.c:1032
fuse_kill_sb_anon+0x1d/0x20 fs/fuse/inode.c:1256
deactivate_locked_super+0x97/0x100 fs/super.c:329
deactivate_super+0x2bb/0x320 fs/super.c:360
cleanup_mnt+0xbf/0x160 fs/namespace.c:1098
__cleanup_mnt+0x16/0x20 fs/namespace.c:1105
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x1ad6/0x26d0 kernel/exit.c:867
do_group_exit+0x177/0x440 kernel/exit.c:970
get_signal+0x8b0/0x1980 kernel/signal.c:2517
do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445f79
Code: Bad RIP value.
RSP: 002b:00007f081109ada8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006dbc38 RCX: 0000000000445f79
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc38
RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 2f30656c69662f2e R14: 0000000100000001 R15: 0000000000000001
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+b9c89b...@syzkaller.appspotmail.com

Tested on:

commit: c8ce94b8fe53 Merge tag 'mips_fixes_4.20_3' of git://git.ke..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=73e2bc0cb6463446

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=1576d45d400000

Note: testing is done by a robot and is best-effort only.