WARNING in ovl_create_or_link

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: e3c1b273 Linux 4.14.132
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13589eaba00000
kernel config: https://syzkaller.appspot.com/x/.config?x=a9ac034723e7e02b
dashboard link: https://syzkaller.appspot.com/bug?extid=7cdbbadfa983b60d6fa9
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11444615a00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1141893ba00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7cdbba...@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
audit: type=1400 audit(1562193882.744:36): avc: denied { map } for
pid=7064 comm="syz-executor539" path="/root/syz-executor539991880"
dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7064 at fs/overlayfs/dir.c:523
ovl_create_or_link+0x6c9/0x11e0 fs/overlayfs/dir.c:523
audit: type=1804 audit(1562193882.744:37): pid=7064 uid=0 auid=4294967295
ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
op="invalid_pcr" cause="open_writers" comm="syz-executor539"
name="/root/file0/file0" dev="sda1" ino=16487 res=1
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7064 Comm: syz-executor539 Not tainted 4.14.132 #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x19c lib/dump_stack.c:53
panic+0x1f2/0x426 kernel/panic.c:182
__warn.cold+0x2f/0x36 kernel/panic.c:546
report_bug+0x216/0x254 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:177 [inline]
fixup_bug arch/x86/kernel/traps.c:172 [inline]
do_error_trap+0x1bb/0x310 arch/x86/kernel/traps.c:295
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:960
RIP: 0010:ovl_create_or_link+0x6c9/0x11e0 fs/overlayfs/dir.c:523
RSP: 0018:ffff8880853ffbc0 EFLAGS: 00010297
RAX: ffff8880966be2c0 RBX: ffff88809a2ec530 RCX: 1ffff110134610ef
RDX: 0000000000000000 RSI: ffff88809a311544 RDI: ffff88809a2ec538
RBP: ffff8880853ffd30 R08: ffff8880966be2c0 R09: ffff8880966bec00
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88809a311540
ovl_link+0x157/0x1a1 fs/overlayfs/dir.c:614
vfs_link+0x6bd/0xa50 fs/namei.c:4261
SYSC_linkat fs/namei.c:4329 [inline]
SyS_linkat fs/namei.c:4285 [inline]
SYSC_link fs/namei.c:4352 [inline]
SyS_link+0x329/0x500 fs/namei.c:4350
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x440309
RSP: 002b:00007ffcf378b268 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440309
RDX: 0000000000440309 RSI: 0000000020000040 RDI: 0000000020000140
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000401b90
R13: 0000000000401c20 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


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