WARNING in ovl_real_fdget_meta

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: cb1f9a16 Linux 4.19.94
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=140e069ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9d03b07719ed036e
dashboard link: https://syzkaller.appspot.com/bug?extid=e967b3e531e31a44f295
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e967b3...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 24534 at fs/overlayfs/file.c:58 ovl_change_flags
fs/overlayfs/file.c:58 [inline]
WARNING: CPU: 0 PID: 24534 at fs/overlayfs/file.c:58
ovl_real_fdget_meta.cold+0x11/0x1e fs/overlayfs/file.c:109
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 24534 Comm: syz-executor.2 Not tainted 4.19.94-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+0x197/0x210 lib/dump_stack.c:118
panic+0x26a/0x50e kernel/panic.c:186
__warn.cold+0x20/0x53 kernel/panic.c:541
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1037
RIP: 0010:ovl_change_flags fs/overlayfs/file.c:58 [inline]
RIP: 0010:ovl_real_fdget_meta.cold+0x11/0x1e fs/overlayfs/file.c:109
Code: e9 b3 fd ff ff e8 fc ca 3f ff e9 fb fd ff ff e8 f2 ca 3f ff e9 15 fe
ff ff e8 28 32 08 ff 48 c7 c7 20 20 d5 87 e8 b0 95 f2 fe <0f> 0b 41 bc fb
ff ff ff e9 98 c6 ff ff e8 0a 32 08 ff 48 c7 c7 20
RSP: 0018:ffff88808e937ba0 EFLAGS: 00010282
RAX: 0000000000000024 RBX: 0000000004048000 RCX: 0000000000000000
kauditd_printk_skb: 2 callbacks suppressed
audit: type=1804 audit(1578716813.199:312): pid=24551 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-executor.1"
name="/root/syzkaller-testdir601507520/syzkaller.7YCBtT/501/bus" dev="sda1"
ino=17041 res=1
RDX: 0000000000000000 RSI: ffffffff81558bb6 RDI: ffffed1011d26f66
RBP: ffff88808e937bd0 R08: 0000000000000024 R09: ffffed1015d05079
R10: ffffed1015d05078 R11: ffff8880ae8283c7 R12: 000000000000a000
R13: ffff8880878e47c0 R14: ffff8880878e4838 R15: ffff88809483b6b0
ovl_real_fdget fs/overlayfs/file.c:116 [inline]
ovl_read_iter+0x11a/0x363 fs/overlayfs/file.c:241
audit: type=1804 audit(1578716813.199:313): pid=24551 uid=0 auid=4294967295
ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
op=invalid_pcr cause=ToMToU comm="syz-executor.1"
name="/root/syzkaller-testdir601507520/syzkaller.7YCBtT/501/bus" dev="sda1"
ino=17041 res=1
call_read_iter include/linux/fs.h:1814 [inline]
new_sync_read fs/read_write.c:406 [inline]
__vfs_read+0x584/0x800 fs/read_write.c:418
vfs_read+0x194/0x3d0 fs/read_write.c:452
ksys_read+0x14f/0x2d0 fs/read_write.c:579
__do_sys_read fs/read_write.c:589 [inline]
__se_sys_read fs/read_write.c:587 [inline]
__x64_sys_read+0x73/0xb0 fs/read_write.c:587
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
audit: type=1804 audit(1578716813.199:314): pid=24557 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-executor.1"
name="/root/syzkaller-testdir601507520/syzkaller.7YCBtT/502/bus" dev="sda1"
ino=17041 res=1
RSP: 002b:00007f80aa9a3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 0000000000001000 RSI: 0000000020000300 RDI: 0000000000000003
overlayfs: failed to resolve './file0': -2
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f80aa9a46d4
R13: 00000000004c964f R14: 00000000004e21e0 R15: 00000000ffffffff
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#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: cb1f9a16 Linux 4.19.94
git tree: linux-4.19.y

console output: https://syzkaller.appspot.com/x/log.txt?x=15d7f549e00000

kernel config: https://syzkaller.appspot.com/x/.config?x=9d03b07719ed036e
dashboard link: https://syzkaller.appspot.com/bug?extid=e967b3e531e31a44f295
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13308269e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15e6cd71e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e967b3...@syzkaller.appspotmail.com

audit: type=1400 audit(1578719296.925:36): avc: denied { map } for
pid=7947 comm="syz-executor587" path="/root/syz-executor587839102"
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 ]------------
audit: type=1400 audit(1578719296.925:37): avc: denied { associate } for
pid=7947 comm="syz-executor587" name="file0"
scontext=unconfined_u:object_r:unlabeled_t:s0
tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1
WARNING: CPU: 1 PID: 7947 at fs/overlayfs/file.c:58 ovl_change_flags
fs/overlayfs/file.c:58 [inline]
WARNING: CPU: 1 PID: 7947 at fs/overlayfs/file.c:58

ovl_real_fdget_meta.cold+0x11/0x1e fs/overlayfs/file.c:109
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 7947 Comm: syz-executor587 Not tainted 4.19.94-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+0x197/0x210 lib/dump_stack.c:118
panic+0x26a/0x50e kernel/panic.c:186
__warn.cold+0x20/0x53 kernel/panic.c:541
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1037
RIP: 0010:ovl_change_flags fs/overlayfs/file.c:58 [inline]
RIP: 0010:ovl_real_fdget_meta.cold+0x11/0x1e fs/overlayfs/file.c:109
Code: e9 b3 fd ff ff e8 fc ca 3f ff e9 fb fd ff ff e8 f2 ca 3f ff e9 15 fe
ff ff e8 28 32 08 ff 48 c7 c7 20 20 d5 87 e8 b0 95 f2 fe <0f> 0b 41 bc fb
ff ff ff e9 98 c6 ff ff e8 0a 32 08 ff 48 c7 c7 20

RSP: 0018:ffff88809a2c7ba0 EFLAGS: 00010282

RAX: 0000000000000024 RBX: 0000000004048000 RCX: 0000000000000000

RDX: 0000000000000000 RSI: ffffffff81558bb6 RDI: ffffed1013458f66
RBP: ffff88809a2c7bd0 R08: 0000000000000024 R09: ffffed1015d25079
R10: ffffed1015d25078 R11: ffff8880ae9283c7 R12: 000000000000a000
R13: ffff88809925ccc0 R14: ffff88809925cd38 R15: ffff8880949bf530

ovl_real_fdget fs/overlayfs/file.c:116 [inline]
ovl_read_iter+0x11a/0x363 fs/overlayfs/file.c:241

call_read_iter include/linux/fs.h:1814 [inline]
new_sync_read fs/read_write.c:406 [inline]
__vfs_read+0x584/0x800 fs/read_write.c:418
vfs_read+0x194/0x3d0 fs/read_write.c:452
ksys_read+0x14f/0x2d0 fs/read_write.c:579
__do_sys_read fs/read_write.c:589 [inline]
__se_sys_read fs/read_write.c:587 [inline]
__x64_sys_read+0x73/0xb0 fs/read_write.c:587
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

RIP: 0033:0x4402b9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc9f576bc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402b9

RDX: 0000000000001000 RSI: 0000000020000300 RDI: 0000000000000003

RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401b40
R13: 0000000000401bd0 R14: 0000000000000000 R15: 0000000000000000