linux-kernel - general protection fault in loop_validate

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Message-ID: <00000000000098bf7d05845616d7@google.com>
Date:   Sun, 17 Mar 2019 20:36:04 -0700
From:   syzbot <syzbot+9bdc1adc1c55e7fe765b@...kaller.appspotmail.com>
To:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: general protection fault in loop_validate_file (2)

Hello,

syzbot found the following crash on:

HEAD commit:    9c7dc824 Merge tag '5.1-rc-smb3' of git://git.samba.org/sf..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148a35fb200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7e1aaa1cfbfe1abf
dashboard link: https://syzkaller.appspot.com/bug?extid=9bdc1adc1c55e7fe765b
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+9bdc1adc1c55e7fe765b@...kaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 9499 Comm: syz-executor.4 Not tainted 5.0.0+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:loop_validate_file+0x23e/0x310 drivers/block/loop.c:652
Code: 00 48 89 f8 48 c1 e8 03 42 80 3c 38 00 0f 85 d4 00 00 00 4d 8b a4 24  
f0 00 00 00 49 8d bc 24 b8 01 00 00 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00  
0f 85 a8 00 00 00 4d 8b a4 24 b8 01 00 00 4c 89 e0
RSP: 0018:ffff88804d2bfb18 EFLAGS: 00010202
RAX: 0000000000000037 RBX: ffff888095ffa3d8 RCX: ffffc9000e657000
RDX: 0000000000000077 RSI: ffffffff83e754ed RDI: 00000000000001b8
RBP: ffff88804d2bfb40 R08: ffff88808eab41c0 R09: fffffbfff11d981d
R10: ffff88804d2bfb40 R11: ffffffff88ecc0e7 R12: 0000000000000000
R13: 0000000000000002 R14: ffff888095ffa800 R15: dffffc0000000000
FS:  00007f04b0c91700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000000a7af8000 CR4: 00000000001406e0
Call Trace:
  loop_set_fd drivers/block/loop.c:930 [inline]
  lo_ioctl+0x99d/0x2150 drivers/block/loop.c:1542
  __blkdev_driver_ioctl block/ioctl.c:303 [inline]
  blkdev_ioctl+0xee8/0x1c40 block/ioctl.c:605
  block_ioctl+0xee/0x130 fs/block_dev.c:1931
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:509 [inline]
  do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
  __do_sys_ioctl fs/ioctl.c:720 [inline]
  __se_sys_ioctl fs/ioctl.c:718 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458079
Code: ad b8 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 b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f04b0c90c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458079
RDX: 0000000000000004 RSI: 0000000000004c00 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f04b0c916d4
R13: 00000000004c1252 R14: 00000000004d3160 R15: 00000000ffffffff
Modules linked in:
---[ end trace 81b29486bae7280a ]---
RIP: 0010:loop_validate_file+0x23e/0x310 drivers/block/loop.c:652
Code: 00 48 89 f8 48 c1 e8 03 42 80 3c 38 00 0f 85 d4 00 00 00 4d 8b a4 24  
f0 00 00 00 49 8d bc 24 b8 01 00 00 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00  
0f 85 a8 00 00 00 4d 8b a4 24 b8 01 00 00 4c 89 e0
RSP: 0018:ffff88804d2bfb18 EFLAGS: 00010202
RAX: 0000000000000037 RBX: ffff888095ffa3d8 RCX: ffffc9000e657000
RDX: 0000000000000077 RSI: ffffffff83e754ed RDI: 00000000000001b8
RBP: ffff88804d2bfb40 R08: ffff88808eab41c0 R09: fffffbfff11d981d
R10: ffff88804d2bfb40 R11: ffffffff88ecc0e7 R12: 0000000000000000
R13: 0000000000000002 R14: ffff888095ffa800 R15: dffffc0000000000
FS:  00007f04b0c91700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000000a7af8000 CR4: 00000000001406e0


---
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