[v6.6] KASAN: slab-out-of-bounds Read in reiserfs_xattr_get (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8cee53b8eaeb Linux 6.6.134
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10dafb02580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=4f7007a58fe4293f83f8
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4c0eb6df7b4a/disk-8cee53b8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/38626ee912e4/vmlinux-8cee53b8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/646a84f3433a/bzImage-8cee53b8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4f7007...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in reiserfs_xattr_get+0xfe/0x5a0 fs/reiserfs/xattr.c:676
Read of size 8 at addr ffff8880290ce598 by task syz.3.3126/12339

CPU: 1 PID: 12339 Comm: syz.3.3126 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xa8/0x210 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
reiserfs_xattr_get+0xfe/0x5a0 fs/reiserfs/xattr.c:676
reiserfs_get_acl+0x7e/0x6a0 fs/reiserfs/xattr_acl.c:215
__get_acl+0x273/0x400 fs/posix_acl.c:160
check_acl+0x3a/0x150 fs/namei.c:310
acl_permission_check fs/namei.c:355 [inline]
generic_permission+0x381/0x590 fs/namei.c:408
do_inode_permission fs/namei.c:462 [inline]
inode_permission+0x23d/0x480 fs/namei.c:529
may_open+0x2e9/0x440 fs/namei.c:3268
do_open fs/namei.c:3638 [inline]
path_openat+0x268c/0x3230 fs/namei.c:3797
do_filp_open+0x1f5/0x430 fs/namei.c:3824
do_sys_openat2+0x134/0x1d0 fs/open.c:1421
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0x139/0x160 fs/open.c:1447
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcb55f5d04e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fcb56e8ada8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fcb56e8b6c0 RCX: 00007fcb55f5d04e
RDX: 0000000000010000 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 0000200000000140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000040
R13: 00007fcb56e8aea0 R14: 0000000000006208 R15: 0000200000000340
</TASK>

Allocated by task 1:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
____kasan_kmalloc mm/kasan/common.c:375 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
bus_add_driver+0x162/0x630 drivers/base/bus.c:659
driver_register+0x23a/0x310 drivers/base/driver.c:246
usb_register_driver+0x206/0x3d0 drivers/usb/core/driver.c:1062
do_one_initcall+0x242/0x790 init/main.c:1250
do_initcall_level+0x137/0x1f0 init/main.c:1312
do_initcalls+0x69/0xd0 init/main.c:1328
kernel_init_freeable+0x3ed/0x580 init/main.c:1565
kernel_init+0x1d/0x1c0 init/main.c:1455
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff8880290ce400
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 200 bytes to the right of
allocated 208-byte region [ffff8880290ce400, ffff8880290ce4d0)

The buggy address belongs to the physical page:
page:ffffea0000a43380 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x290ce
head:ffffea0000a43380 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c41b40 ffffea0000adec00 dead000000000004
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2, tgid 2 (kthreadd), ts 13963579578, free_ts 0
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581
prep_new_page mm/page_alloc.c:1588 [inline]
get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220
__alloc_pages+0x1f0/0x460 mm/page_alloc.c:4500
alloc_slab_page+0x5d/0x160 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2d0 mm/slub.c:2081
___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
__kmem_cache_alloc_node+0x19e/0x250 mm/slub.c:3534
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
set_kthread_struct+0xb7/0x1f0 kernel/kthread.c:118
copy_process+0x10a3/0x3d80 kernel/fork.c:2434
kernel_clone+0x24b/0x8a0 kernel/fork.c:2915
kernel_thread+0x13f/0x1b0 kernel/fork.c:2977
create_kthread kernel/kthread.c:411 [inline]
kthreadd+0x57f/0x750 kernel/kthread.c:766
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
page_owner free stack trace missing

Memory state around the buggy address:
ffff8880290ce480: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
ffff8880290ce500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880290ce580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880290ce600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880290ce680: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
==================================================================


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