[Android 5.15] KASAN: out-of-bounds Read in ext4_xattr_set_entry (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0d918fa8e88d Merge android13-5.15 into android13-5.15-lts
git tree: android13-5.15-lts
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16edb48c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=790c33d0affdb7c8
dashboard link: https://syzkaller.appspot.com/bug?extid=3f3e4714a8b66ff246cf
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1665848c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1503d3d4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/44bd4d8dc6d6/disk-0d918fa8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a48b4d3211ff/vmlinux-0d918fa8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f3e620176b03/bzImage-0d918fa8.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/2daea9e2bc13/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=110daebc580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3f3e47...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in ext4_xattr_set_entry+0x13a3/0x37d0 fs/ext4/xattr.c:1747
Read of size 18446744073709551540 at addr ffff8881047aa870 by task syz-executor111/288

CPU: 1 PID: 288 Comm: syz-executor111 Not tainted 5.15.185-syzkaller-00032-g0d918fa8e88d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
__dump_stack+0x21/0x30 lib/dump_stack.c:88
dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:427 [inline]
kasan_report+0xf1/0x140 mm/kasan/report.c:444
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x280/0x290 mm/kasan/generic.c:189
memmove+0x2d/0x70 mm/kasan/shadow.c:54
ext4_xattr_set_entry+0x13a3/0x37d0 fs/ext4/xattr.c:1747
ext4_xattr_block_set+0x8cd/0x2cb0 fs/ext4/xattr.c:2004
ext4_xattr_set_handle+0xba5/0x12b0 fs/ext4/xattr.c:2412
ext4_xattr_set+0x22a/0x320 fs/ext4/xattr.c:2522
ext4_xattr_trusted_set+0x3c/0x50 fs/ext4/xattr_trusted.c:38
__vfs_setxattr+0x3e1/0x430 fs/xattr.c:182
__vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
__vfs_setxattr_locked+0x212/0x230 fs/xattr.c:277
vfs_setxattr+0x168/0x2f0 fs/xattr.c:303
do_setxattr fs/xattr.c:588 [inline]
setxattr+0x2da/0x300 fs/xattr.c:611
path_setxattr+0x142/0x280 fs/xattr.c:630
__do_sys_lsetxattr fs/xattr.c:653 [inline]
__se_sys_lsetxattr fs/xattr.c:649 [inline]
__x64_sys_lsetxattr+0xc2/0xe0 fs/xattr.c:649
x64_sys_call+0x8cc/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:190
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3809124a79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 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:00007ffc4b50c698 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00002000000001c0 RCX: 00007f3809124a79
RDX: 0000200000000040 RSI: 0000200000000300 RDI: 0000200000000100
RBP: 0000200000000040 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000fe37 R11: 0000000000000246 R12: 0072657070752e79
R13: 0032656c69662f2e R14: 0031656c69662f2e R15: 0000000000000001
</TASK>

Allocated by task 288:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:433 [inline]
____kasan_kmalloc mm/kasan/common.c:512 [inline]
__kasan_kmalloc+0xda/0x110 mm/kasan/common.c:521
kasan_kmalloc include/linux/kasan.h:227 [inline]
__kmalloc_track_caller+0x13c/0x2c0 mm/slub.c:4954
kmemdup+0x26/0x60 mm/util.c:132
ext4_xattr_block_set+0x7e2/0x2cb0 fs/ext4/xattr.c:1952
ext4_xattr_set_handle+0xba5/0x12b0 fs/ext4/xattr.c:2412
ext4_xattr_set+0x22a/0x320 fs/ext4/xattr.c:2522
ext4_xattr_trusted_set+0x3c/0x50 fs/ext4/xattr_trusted.c:38
__vfs_setxattr+0x3e1/0x430 fs/xattr.c:182
__vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
__vfs_setxattr_locked+0x212/0x230 fs/xattr.c:277
vfs_setxattr+0x168/0x2f0 fs/xattr.c:303
do_setxattr fs/xattr.c:588 [inline]
setxattr+0x2da/0x300 fs/xattr.c:611
path_setxattr+0x142/0x280 fs/xattr.c:630
__do_sys_lsetxattr fs/xattr.c:653 [inline]
__se_sys_lsetxattr fs/xattr.c:649 [inline]
__x64_sys_lsetxattr+0xc2/0xe0 fs/xattr.c:649
x64_sys_call+0x8cc/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:190
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff8881047aa800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 112 bytes inside of
1024-byte region [ffff8881047aa800, ffff8881047aac00)
The buggy address belongs to the page:
page:ffffea000411ea00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1047a8
head:ffffea000411ea00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 ffff888100043080
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 284, ts 22712890253, free_ts 22712055974
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605
prep_new_page+0x1c/0x110 mm/page_alloc.c:2611
get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485
__alloc_pages+0x18f/0x440 mm/page_alloc.c:5795
alloc_slab_page mm/slub.c:-1 [inline]
allocate_slab mm/slub.c:1932 [inline]
new_slab+0xa1/0x4d0 mm/slub.c:1995
___slab_alloc+0x381/0x810 mm/slub.c:3028
__slab_alloc+0x49/0x90 mm/slub.c:3115
slab_alloc_node mm/slub.c:3206 [inline]
slab_alloc mm/slub.c:3250 [inline]
__kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4949
kmalloc_reserve net/core/skbuff.c:357 [inline]
__alloc_skb+0x21a/0x740 net/core/skbuff.c:428
alloc_skb_fclone include/linux/skbuff.h:1233 [inline]
sk_stream_alloc_skb+0x21a/0xb60 net/ipv4/tcp.c:889
tcp_sendmsg_locked+0xc3e/0x3590 net/ipv4/tcp.c:1314
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1457
inet_sendmsg+0xa5/0xc0 net/ipv4/af_inet.c:830
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
sock_write_iter+0x29c/0x380 net/socket.c:1079
call_write_iter include/linux/fs.h:2212 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x802/0xf70 fs/read_write.c:594
ksys_write+0x140/0x240 fs/read_write.c:647
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1472 [inline]
free_pcp_prepare mm/page_alloc.c:1544 [inline]
free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534
free_unref_page+0xa2/0x550 mm/page_alloc.c:3616
free_the_page mm/page_alloc.c:805 [inline]
__free_pages+0x6c/0x100 mm/page_alloc.c:5871
__free_slab+0xe8/0x1e0 mm/slub.c:2020
free_slab mm/slub.c:2035 [inline]
discard_slab mm/slub.c:2041 [inline]
__unfreeze_partials+0x160/0x190 mm/slub.c:2527
put_cpu_partial+0xc6/0x120 mm/slub.c:2607
__slab_free+0x1d4/0x290 mm/slub.c:3390
do_slab_free mm/slub.c:3509 [inline]
___cache_free+0x104/0x120 mm/slub.c:3530
qlink_free+0x4d/0x90 mm/kasan/quarantine.c:157
qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:443
kasan_slab_alloc include/linux/kasan.h:217 [inline]
slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550
slab_alloc_node mm/slub.c:3240 [inline]
slab_alloc mm/slub.c:3250 [inline]
kmem_cache_alloc_trace+0xfb/0x270 mm/slub.c:3267
kmalloc include/linux/slab.h:616 [inline]
kzalloc include/linux/slab.h:747 [inline]
kobject_uevent_env+0x272/0x700 lib/kobject_uevent.c:539
kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657

Memory state around the buggy address:
ffff8881047aa700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881047aa780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881047aa800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^
ffff8881047aa880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8881047aa900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup