general protection fault in kernfs_name_hash (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fdd06dc6b0f8 ANDROID: GKI: db845c: Update symbols list and..
git tree: android12-5.10-lts
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1573809bf00000
kernel config: https://syzkaller.appspot.com/x/.config?x=298c89d0104c8e66
dashboard link: https://syzkaller.appspot.com/bug?extid=50473482bc396bb5e953
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13a86c60080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1730cba7f00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+504734...@syzkaller.appspotmail.com

RBP: 00007ffc1a278760 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000004
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
---[ end trace 2e1e7d352c52daaf ]---
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: 377 Comm: syz-executor277 Tainted: G W 5.10.117-syzkaller-00814-gfdd06dc6b0f8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:strlen+0x3a/0x80 lib/string.c:568
Code: c0 ff ff ff ff 49 bf 00 00 00 00 00 fc ff df 48 89 fb 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 49 89 c4 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 75 12 48 ff c3 49 8d 44 24 01 43 80 7c 26 01
RSP: 0018:ffffc9000096fb68 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8881065b4f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000096fb88 R08: ffffffff81d1390c R09: fffff5200012df75
R10: fffff5200012df75 R11: 1ffff9200012df74 R12: ffffffffffffffff
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS: 00005555556e7300(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc523fb29a0 CR3: 00000001087b5000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kernfs_name_hash+0x21/0x240 fs/kernfs/dir.c:302
kernfs_find_ns+0x72/0x280 fs/kernfs/dir.c:841
kernfs_remove_by_name_ns+0x36/0x90 fs/kernfs/dir.c:1514
kernfs_remove_by_name include/linux/kernfs.h:608 [inline]
sysfs_remove_link+0x50/0x60 fs/sysfs/symlink.c:152
del_gendisk+0xbe0/0xe20 block/genhd.c:951
loop_remove+0x46/0xb0 drivers/block/loop.c:2185
loop_control_ioctl+0x67f/0x740 drivers/block/loop.c:2284
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl+0x115/0x190 fs/ioctl.c:739
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
do_syscall_64+0x34/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fc523f83069
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc1a278748 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fc523f83069
RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000003
RBP: 00007ffc1a278760 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000004
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 2e1e7d352c52dab0 ]---
RIP: 0010:strlen+0x3a/0x80 lib/string.c:568
Code: c0 ff ff ff ff 49 bf 00 00 00 00 00 fc ff df 48 89 fb 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 49 89 c4 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 75 12 48 ff c3 49 8d 44 24 01 43 80 7c 26 01
RSP: 0018:ffffc9000096fb68 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8881065b4f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000096fb88 R08: ffffffff81d1390c R09: fffff5200012df75
R10: fffff5200012df75 R11: 1ffff9200012df74 R12: ffffffffffffffff
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS: 00005555556e7300(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc1a278728 CR3: 00000001087b5000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 5 bytes skipped:
0: 49 bf 00 00 00 00 00 movabs $0xdffffc0000000000,%r15
7: fc ff df
a: 48 89 fb mov %rdi,%rbx
d: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
14: 00 00 00 00
18: 0f 1f 00 nopl (%rax)
1b: 49 89 c4 mov %rax,%r12
1e: 48 89 d8 mov %rbx,%rax
21: 48 c1 e8 03 shr $0x3,%rax
* 25: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax <-- trapping instruction
2a: 84 c0 test %al,%al
2c: 75 12 jne 0x40
2e: 48 ff c3 inc %rbx
31: 49 8d 44 24 01 lea 0x1(%r12),%rax
36: 43 rex.XB
37: 80 .byte 0x80
38: 7c 26 jl 0x60
3a: 01 .byte 0x1


---
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[syzbot]

syzbot has bisected this issue to:

commit bda49ad0602e5250a9d3dd61deda19d3e5615c54
Author: Bart Van Assche <bvana...@google.com>
Date: Mon Aug 2 17:05:29 2021 +0000

FROMGIT: loop: Select I/O scheduler 'none' from inside add_disk()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16b6ecf8080000
start commit: fdd06dc6b0f8 ANDROID: GKI: db845c: Update symbols list and..
git tree: android12-5.10-lts
final oops: https://syzkaller.appspot.com/x/report.txt?x=15b6ecf8080000
console output: https://syzkaller.appspot.com/x/log.txt?x=11b6ecf8080000

kernel config: https://syzkaller.appspot.com/x/.config?x=298c89d0104c8e66
dashboard link: https://syzkaller.appspot.com/bug?extid=50473482bc396bb5e953

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13a86c60080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1730cba7f00000

Reported-by: syzbot+504734...@syzkaller.appspotmail.com
Fixes: bda49ad0602e ("FROMGIT: loop: Select I/O scheduler 'none' from inside add_disk()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection