[syzbot] general protection fault in exfat_fill_super

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    4d48f589d294 Add linux-next specific files for 20221021
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11fc516e880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2c4b7d600a5739a6
dashboard link: https://syzkaller.appspot.com/bug?extid=74fa8cb75d0a18df4790
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1056a9b4880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14613b3c880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0c86bd0b39a0/disk-4d48f589.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/074059d37f1f/vmlinux-4d48f589.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/6d392b37ac66/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+74fa8cb75d0a18df4790@xxxxxxxxxxxxxxxxxxxxxxxxx

loop0: detected capacity change from 0 to 4096
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 3610 Comm: syz-executor183 Not tainted 6.1.0-rc1-next-20221021-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:strcmp+0x35/0xb0 lib/string.c:281
Code: df 41 54 55 53 48 89 fb 48 83 ec 08 eb 08 40 84 ed 74 5d 4c 89 e6 48 89 df 48 83 c3 01 48 89 f8 48 89 fa 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 04 84 c0 75 50 0f b6 6b ff 4c 8d 66 01 48
RSP: 0018:ffffc90003e3fbd8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff89e65300 RDI: 0000000000000000
RBP: ffffc90003e3fd38 R08: 0000000000000005 R09: 0000000000000100
R10: 0000000000000100 R11: 1ffffffff17b2629 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880766a6000 R15: 0000000000000100
FS:  0000555556f6b300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005d84c8 CR3: 0000000072c9f000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 exfat_fill_super+0x16d0/0x2990 fs/exfat/super.c:659
 get_tree_bdev+0x440/0x760 fs/super.c:1324
 vfs_get_tree+0x89/0x2f0 fs/super.c:1531
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fa8d401085a
Code: 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdbcd10b08 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fa8d401085a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffdbcd10b20
RBP: 00007ffdbcd10b20 R08: 00007ffdbcd10b60 R09: 0000555556f6b2c0
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000000004
R13: 00007ffdbcd10b60 R14: 000000000000001d R15: 00000000200004b8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:strcmp+0x35/0xb0 lib/string.c:281
Code: df 41 54 55 53 48 89 fb 48 83 ec 08 eb 08 40 84 ed 74 5d 4c 89 e6 48 89 df 48 83 c3 01 48 89 f8 48 89 fa 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 04 84 c0 75 50 0f b6 6b ff 4c 8d 66 01 48
RSP: 0018:ffffc90003e3fbd8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff89e65300 RDI: 0000000000000000
RBP: ffffc90003e3fd38 R08: 0000000000000005 R09: 0000000000000100
R10: 0000000000000100 R11: 1ffffffff17b2629 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880766a6000 R15: 0000000000000100
FS:  0000555556f6b300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005d84c8 CR3: 0000000072c9f000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	df 41 54             	filds  0x54(%rcx)
   3:	55                   	push   %rbp
   4:	53                   	push   %rbx
   5:	48 89 fb             	mov    %rdi,%rbx
   8:	48 83 ec 08          	sub    $0x8,%rsp
   c:	eb 08                	jmp    0x16
   e:	40 84 ed             	test   %bpl,%bpl
  11:	74 5d                	je     0x70
  13:	4c 89 e6             	mov    %r12,%rsi
  16:	48 89 df             	mov    %rbx,%rdi
  19:	48 83 c3 01          	add    $0x1,%rbx
  1d:	48 89 f8             	mov    %rdi,%rax
  20:	48 89 fa             	mov    %rdi,%rdx
  23:	48 c1 e8 03          	shr    $0x3,%rax
  27:	83 e2 07             	and    $0x7,%edx
* 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2f:	38 d0                	cmp    %dl,%al
  31:	7f 04                	jg     0x37
  33:	84 c0                	test   %al,%al
  35:	75 50                	jne    0x87
  37:	0f b6 6b ff          	movzbl -0x1(%rbx),%ebp
  3b:	4c 8d 66 01          	lea    0x1(%rsi),%r12
  3f:	48                   	rex.W


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