[v6.6] KASAN: use-after-free Read in udf_add_fid_counter

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1058d77c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=ae5087bff16eb8f5c3c6
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ae5087...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in le32_add_cpu include/linux/byteorder/generic.h:151 [inline]
BUG: KASAN: use-after-free in udf_add_fid_counter+0x1a2/0x210 fs/udf/namei.c:-1
Read of size 4 at addr ffff8880ae2c85c0 by task syz.7.1306/11383

CPU: 1 PID: 11383 Comm: syz.7.1306 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x220 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
le32_add_cpu include/linux/byteorder/generic.h:151 [inline]
udf_add_fid_counter+0x1a2/0x210 fs/udf/namei.c:-1
udf_rename+0x941/0xcc0 fs/udf/namei.c:883
vfs_rename+0xb96/0xec0 fs/namei.c:4880
do_renameat2+0x8a1/0xc70 fs/namei.c:5033
__do_sys_rename fs/namei.c:5079 [inline]
__se_sys_rename fs/namei.c:5077 [inline]
__x64_sys_rename+0x86/0x90 fs/namei.c:5077
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb35418f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb355096038 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007fb3543e6180 RCX: 00007fb35418f749
RDX: 0000000000000000 RSI: 0000200000000100 RDI: 0000200000000040
RBP: 00007fb354213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb3543e6218 R14: 00007fb3543e6180 R15: 00007ffce0c951d8
</TASK>

The buggy address belongs to the physical page:
page:ffffea0002b8b200 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xae2c8
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 ffffea0002b8b208 ffffea0002b8b208 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
ffff8880ae2c8480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff8880ae2c8500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880ae2c8580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff8880ae2c8600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff8880ae2c8680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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