BUG: unable to handle kernel paging request in do_mount

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 690285a9380d Linux 4.14.279
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=108a5f3ef00000
kernel config: https://syzkaller.appspot.com/x/.config?x=f133a7983d091216
dashboard link: https://syzkaller.appspot.com/bug?extid=73d624a1519a6b17fbf5
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+73d624...@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fff6f193eff R14: 00007f7a83c82300 R15: 0000000000022000
BUG: unable to handle kernel paging request at fffffffffffffffc
IP: do_new_mount fs/namespace.c:2577 [inline]
IP: do_mount+0x1ef2/0x2a30 fs/namespace.c:2905
PGD 8e6b067 P4D 8e6b067 PUD 8e6d067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
PM: Image not found (code -6)
Modules linked in:
CPU: 1 PID: 15012 Comm: syz-executor.2 Not tainted 4.14.279-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880593a2300 task.stack: ffff8880597c0000
RIP: 0010:do_new_mount fs/namespace.c:2577 [inline]
RIP: 0010:do_mount+0x1ef2/0x2a30 fs/namespace.c:2905
RSP: 0018:ffff8880597c7d90 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 00000000fffffff4 RCX: ffffc900061c1000
RDX: 1fffffffffffffff RSI: ffffffff818e8bc4 RDI: fffffffffffffffc
RBP: fffffffffffffff4 R08: ffffffff8ba4d19c R09: 0000000000000001
R10: 0000000000000000 R11: ffff8880593a2300 R12: ffff8880a8ed1a28
R13: ffffffff891e9ee0 R14: 0000000000000000 R15: 0000000000000020
FS: 00007f7a83c82700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000008f5ca000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
SYSC_mount fs/namespace.c:3121 [inline]
SyS_mount+0xa8/0x120 fs/namespace.c:3098
PM: Starting manual resume from disk
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f7a8530d0e9
PM: Image not found (code -6)
RSP: 002b:00007f7a83c82168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f7a8541ff60 RCX: 00007f7a8530d0e9
RDX: 0000000020002000 RSI: 00000000200042c0 RDI: 0000000000000000
RBP: 00007f7a83c821d0 R08: 0000000020002240 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fff6f193eff R14: 00007f7a83c82300 R15: 0000000000022000
Code: c6 ff 48 89 ef 48 63 eb e8 7c 61 ff ff 48 8d 7d 08 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 80 3c 02 00 0f 85 4b 08 00 00 <48> 8b 5d 08 e8 b5 ba c6 ff 48 8d 7b 70 e8 dc 52 b2 ff 4c 89 ef
RIP: do_new_mount fs/namespace.c:2577 [inline] RSP: ffff8880597c7d90
RIP: do_mount+0x1ef2/0x2a30 fs/namespace.c:2905 RSP: ffff8880597c7d90
CR2: fffffffffffffffc
---[ end trace 00eb5bc6ab1dd431 ]---
----------------
Code disassembly (best guess), 1 bytes skipped:
0: ff 48 89 decl -0x77(%rax)
3: ef out %eax,(%dx)
4: 48 63 eb movslq %ebx,%rbp
7: e8 7c 61 ff ff callq 0xffff6188
c: 48 8d 7d 08 lea 0x8(%rbp),%rdi
10: b8 ff ff 37 00 mov $0x37ffff,%eax
15: 48 89 fa mov %rdi,%rdx
18: 48 c1 e0 2a shl $0x2a,%rax
1c: 48 c1 ea 03 shr $0x3,%rdx
20: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
24: 0f 85 4b 08 00 00 jne 0x875
* 2a: 48 8b 5d 08 mov 0x8(%rbp),%rbx <-- trapping instruction
2e: e8 b5 ba c6 ff callq 0xffc6bae8
33: 48 8d 7b 70 lea 0x70(%rbx),%rdi
37: e8 dc 52 b2 ff callq 0xffb25318
3c: 4c 89 ef mov %r13,%rdi


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 690285a9380d Linux 4.14.279
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=1192c009f00000

kernel config: https://syzkaller.appspot.com/x/.config?x=f133a7983d091216
dashboard link: https://syzkaller.appspot.com/bug?extid=73d624a1519a6b17fbf5
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13a718cef00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15344a21f00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+73d624...@syzkaller.appspotmail.com

RDX: 0000000020002000 RSI: 00000000200042c0 RDI: 0000000000000000

RBP: 00007ffc9b2b74e0 R08: 0000000020002240 R09: 000000000000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 00007ffc9b2b7500 R14: 00007ffc9b2b74f0 R15: 00007ffc9b2b74d4

BUG: unable to handle kernel paging request at fffffffffffffffc
IP: do_new_mount fs/namespace.c:2577 [inline]
IP: do_mount+0x1ef2/0x2a30 fs/namespace.c:2905
PGD 8e6b067 P4D 8e6b067 PUD 8e6d067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN

Modules linked in:
CPU: 1 PID: 8516 Comm: syz-executor109 Not tainted 4.14.279-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

task: ffff88809aed0040 task.stack: ffff8880995e8000

RIP: 0010:do_new_mount fs/namespace.c:2577 [inline]
RIP: 0010:do_mount+0x1ef2/0x2a30 fs/namespace.c:2905

RSP: 0018:ffff8880995efd90 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 00000000fffffff4 RCX: 0000000000000000
RDX: 1fffffffffffffff RSI: ffffffff87ccff80 RDI: fffffffffffffffc
RBP: fffffffffffffff4 R08: ffffffff8ba460bc R09: 0000000000000001
R10: 0000000000000000 R11: ffff88809aed0040 R12: ffff8880a8dd4028

R13: ffffffff891e9ee0 R14: 0000000000000000 R15: 0000000000000020

FS: 000055555656d300(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: fffffffffffffffc CR3: 00000000a5773000 CR4: 00000000003406e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
SYSC_mount fs/namespace.c:3121 [inline]
SyS_mount+0xa8/0x120 fs/namespace.c:3098

do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7ff216918509
RSP: 002b:00007ffc9b2b74c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007ff216918509

RDX: 0000000020002000 RSI: 00000000200042c0 RDI: 0000000000000000

RBP: 00007ffc9b2b74e0 R08: 0000000020002240 R09: 000000000000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 00007ffc9b2b7500 R14: 00007ffc9b2b74f0 R15: 00007ffc9b2b74d4

Code: c6 ff 48 89 ef 48 63 eb e8 7c 61 ff ff 48 8d 7d 08 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 80 3c 02 00 0f 85 4b 08 00 00 <48> 8b 5d 08 e8 b5 ba c6 ff 48 8d 7b 70 e8 dc 52 b2 ff 4c 89 ef

RIP: do_new_mount fs/namespace.c:2577 [inline] RSP: ffff8880995efd90
RIP: do_mount+0x1ef2/0x2a30 fs/namespace.c:2905 RSP: ffff8880995efd90
CR2: fffffffffffffffc
---[ end trace 2d2dc2b7be67814e ]---