[syzbot] [ext4?] KASAN: use-after-free Read in ext4_xattr_list_entries (2)

[syzbot <syzbot+3fbf2337de43f5581aec@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    8e65320d91cd Merge tag 'drm-fixes-2026-06-06' of https://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=106aabec580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b4166e8ea5fbf7e3
dashboard link: https://syzkaller.appspot.com/bug?extid=3fbf2337de43f5581aec
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 (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-8e65320d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0bee42e3c28b/vmlinux-8e65320d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/57e4c1a3c321/bzImage-8e65320d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fbf2337de43f5581aec@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 2048
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
cdc_ether 5-1:1.0: probe with driver cdc_ether failed with error -22
loop0: detected capacity change from 2048 to 64
EXT4-fs error (device loop0): xattr_find_entry:337: inode #15: comm syz.0.0: corrupted xattr entries
==================================================================
BUG: KASAN: use-after-free in ext4_xattr_list_entries+0x302/0x3d0 fs/ext4/xattr.c:724
Read of size 4 at addr ffff8880568de014 by task syz.0.0/5342

CPU: 0 UID: 0 PID: 5342 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_xattr_list_entries+0x302/0x3d0 fs/ext4/xattr.c:724
 ext4_xattr_ibody_list fs/ext4/xattr.c:793 [inline]
 ext4_listxattr+0x221/0x670 fs/ext4/xattr.c:818
 vfs_listxattr fs/xattr.c:511 [inline]
 listxattr+0x112/0x2a0 fs/xattr.c:933
 filename_listxattr fs/xattr.c:966 [inline]
 path_listxattrat+0x1a3/0x3f0 fs/xattr.c:993
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9709f9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f970af29fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000c3
RAX: ffffffffffffffda RBX: 00007f970a215fa0 RCX: 00007f9709f9ce59
RDX: 000000000000002d RSI: 0000200000000100 RDI: 0000200000000140
RBP: 00007f970a032d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f970a216038 R14: 00007f970a215fa0 R15: 00007fff4c5d5648
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x568de
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 ffffea00015a37c8 ffffea000141f208 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:
 ffff8880568ddf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880568ddf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880568de000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                         ^
 ffff8880568de080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880568de100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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