BUG: unable to handle kernel paging request in do_mount

From: syzbot
Date: Fri Sep 21 2018 - 02:44:26 EST

Hello,

syzbot found the following crash on:

HEAD commit: a0cb0cabe4bb Add linux-next specific files for 20180920
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=164d6511400000
kernel config: https://syzkaller.appspot.com/x/.config?x=786006c5dafbadf6
dashboard link: https://syzkaller.appspot.com/bug?extid=73c7fe4f77776505299b
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13650fae400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=118cbf21400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+73c7fe4f77776505299b@xxxxxxxxxxxxxxxxxxxxxxxxx

RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440329
RDX: 0000000020000380 RSI: 00000000200002c0 RDI: 0000000000000000
RBP: 00000000006cb018 R08: 0000000000000000 R09: 0000000000000034
R10: 00000000001800a0 R11: 0000000000000246 R12: 0000000000000003
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
BUG: unable to handle kernel paging request at fffffffffffffff4
PGD 966d067 P4D 966d067 PUD 966f067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 5551 Comm: syz-executor016 Not tainted 4.19.0-rc4-next-20180920+ #76
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:parse_monolithic_mount_data fs/namespace.c:2354 [inline]
RIP: 0010:do_remount fs/namespace.c:2387 [inline]
RIP: 0010:do_mount+0xb3b/0x1db0 fs/namespace.c:2950
Code: 06 00 48 89 c2 48 89 c3 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 24 11 00 00 48 b8 00 00 00 00 00 fc ff df <4c> 8b 33 49 8d 7e 18 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 f8 10
RSP: 0018:ffff8801bb99fc28 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: fffffffffffffff4 RCX: 0000000000000000
RDX: 1ffffffffffffffe RSI: ffffffff81ddffac RDI: 0000000000000282
RBP: ffff8801bb99fdb0 R08: ffff8801d8b0e600 R09: ffffed003b5a5b57
R10: ffffed003b5a5b57 R11: ffff8801dad2dabb R12: ffff8801d3666830
R13: ffff8801c942cb80 R14: ffff8801c942cb80 R15: 0000000000000000
FS: 00000000010de880(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000001d84b5000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
ksys_mount+0x12d/0x140 fs/namespace.c:3175
__do_sys_mount fs/namespace.c:3189 [inline]
__se_sys_mount fs/namespace.c:3186 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3186
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440329
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 5b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc6e4c9ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440329
RDX: 0000000020000380 RSI: 00000000200002c0 RDI: 0000000000000000
RBP: 00000000006cb018 R08: 0000000000000000 R09: 0000000000000034
R10: 00000000001800a0 R11: 0000000000000246 R12: 0000000000000003
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
CR2: fffffffffffffff4
---[ end trace 8aa3e592ff591401 ]---
RIP: 0010:parse_monolithic_mount_data fs/namespace.c:2354 [inline]
RIP: 0010:do_remount fs/namespace.c:2387 [inline]
RIP: 0010:do_mount+0xb3b/0x1db0 fs/namespace.c:2950
Code: 06 00 48 89 c2 48 89 c3 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 24 11 00 00 48 b8 00 00 00 00 00 fc ff df <4c> 8b 33 49 8d 7e 18 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 f8 10
RSP: 0018:ffff8801bb99fc28 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: fffffffffffffff4 RCX: 0000000000000000
RDX: 1ffffffffffffffe RSI: ffffffff81ddffac RDI: 0000000000000282
RBP: ffff8801bb99fdb0 R08: ffff8801d8b0e600 R09: ffffed003b5a5b57
R10: ffffed003b5a5b57 R11: ffff8801dad2dabb R12: ffff8801d3666830
R13: ffff8801c942cb80 R14: ffff8801c942cb80 R15: 0000000000000000
FS: 00000000010de880(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000001d84b5000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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