[syzbot] [udf?] general protection fault in d_splice_alias

From: syzbot
Date: Mon Feb 03 2025 - 14:48:39 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 69e858e0b8b2 Merge tag 'uml-for-linus-6.14-rc1' of git://g..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11bfc518580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d1a6d4df5fcc342f
dashboard link: https://syzkaller.appspot.com/bug?extid=a9c0867e4d1dd0c7ab19
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=125d0eb0580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a595f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a4b4612f419c/disk-69e858e0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/07abf7c78a98/vmlinux-69e858e0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/085b44906cce/bzImage-69e858e0.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/0e8d208f30b1/mount_0.gz

The issue was bisected to:

commit 30d61efe118cad1a73ad2ad66a3298e4abdf9f41
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Jan 6 02:33:17 2025 +0000

9p: fix ->rename_sem exclusion

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1050fddf980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1250fddf980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1450fddf980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a9c0867e4d1dd0c7ab19@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 30d61efe118c ("9p: fix ->rename_sem exclusion")

UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2022/11/22 14:59 (1000)
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 0 UID: 0 PID: 5832 Comm: syz-executor165 Not tainted 6.13.0-syzkaller-09760-g69e858e0b8b2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:__d_unalias fs/dcache.c:2969 [inline]
RIP: 0010:d_splice_alias+0x9cd/0xf30 fs/dcache.c:3037
Code: 48 c1 ea 03 80 3c 02 00 0f 85 4e 05 00 00 49 8b 85 70 ff ff ff 48 ba 00 00 00 00 00 fc ff df 48 8d 78 68 48 89 f9 48 c1 e9 03 <80> 3c 11 00 0f 85 14 05 00 00 48 8b 40 68 48 85 c0 74 31 48 89 44
RSP: 0018:ffffc90003667c18 EFLAGS: 00010212
RAX: 0000000000000000 RBX: ffff88807dbd7318 RCX: 000000000000000d
RDX: dffffc0000000000 RSI: ffffffff82348f0c RDI: 0000000000000068
RBP: ffff8880754107b8 R08: 0000000000000000 R09: ffffed100f23d67a
R10: ffff8880791eb3d3 R11: 0000000000000032 R12: ffff8880791eb318
R13: ffff8880791eafd8 R14: ffff8880791eaeb0 R15: ffff8880791eaf48
FS: 0000555581642380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe875be000 CR3: 0000000076b7a000 CR4: 0000000000350ef0
Call Trace:
<TASK>
udf_lookup+0x191/0x240 fs/udf/namei.c:130
lookup_one_qstr_excl+0x120/0x190 fs/namei.c:1693
do_rmdir+0x247/0x410 fs/namei.c:4444
__do_sys_rmdir fs/namei.c:4474 [inline]
__se_sys_rmdir fs/namei.c:4472 [inline]
__x64_sys_rmdir+0xc5/0x110 fs/namei.c:4472
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9ee0142d99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe875bd248 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 6f72746e6f632f2e RCX: 00007f9ee0142d99
RDX: 00007f9ee0142d99 RSI: 00007f9ee0142d99 RDI: 0000000020000100
RBP: 00007f9ee01b75f0 R08: 00005555816434c0 R09: 00005555816434c0
R10: 00005555816434c0 R11: 0000000000000246 R12: 00007ffe875bd270
R13: 00007ffe875bd498 R14: 431bde82d7b634db R15: 00007f9ee018c03b
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__d_unalias fs/dcache.c:2969 [inline]
RIP: 0010:d_splice_alias+0x9cd/0xf30 fs/dcache.c:3037
Code: 48 c1 ea 03 80 3c 02 00 0f 85 4e 05 00 00 49 8b 85 70 ff ff ff 48 ba 00 00 00 00 00 fc ff df 48 8d 78 68 48 89 f9 48 c1 e9 03 <80> 3c 11 00 0f 85 14 05 00 00 48 8b 40 68 48 85 c0 74 31 48 89 44
RSP: 0018:ffffc90003667c18 EFLAGS: 00010212
RAX: 0000000000000000 RBX: ffff88807dbd7318 RCX: 000000000000000d
RDX: dffffc0000000000 RSI: ffffffff82348f0c RDI: 0000000000000068
RBP: ffff8880754107b8 R08: 0000000000000000 R09: ffffed100f23d67a
R10: ffff8880791eb3d3 R11: 0000000000000032 R12: ffff8880791eb318
R13: ffff8880791eafd8 R14: ffff8880791eaeb0 R15: ffff8880791eaf48
FS: 0000555581642380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe875be000 CR3: 0000000076b7a000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
0: 48 c1 ea 03 shr $0x3,%rdx
4: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
8: 0f 85 4e 05 00 00 jne 0x55c
e: 49 8b 85 70 ff ff ff mov -0x90(%r13),%rax
15: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
1c: fc ff df
1f: 48 8d 78 68 lea 0x68(%rax),%rdi
23: 48 89 f9 mov %rdi,%rcx
26: 48 c1 e9 03 shr $0x3,%rcx
* 2a: 80 3c 11 00 cmpb $0x0,(%rcx,%rdx,1) <-- trapping instruction
2e: 0f 85 14 05 00 00 jne 0x548
34: 48 8b 40 68 mov 0x68(%rax),%rax
38: 48 85 c0 test %rax,%rax
3b: 74 31 je 0x6e
3d: 48 rex.W
3e: 89 .byte 0x89
3f: 44 rex.R

---
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Next message: Charlie Jenkins: "Re: [PATCH v2] riscv: Use Zalrsc extension to implement atomic functions"
Previous message: Andy Shevchenko: "[PATCH v1 1/1] ACPI: property: Fix return value for nval == 0 in acpi_data_prop_read()"
Next in thread: Edward Adam Davis: "Re: [syzbot] [nilfs?] general protection fault in __d_unalias"
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