[Android 5.10] KASAN: use-after-free Read in ext4_get_inode_usage

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1b32327554da Merge 5.10.255 into android13-5.10-lts
git tree: android13-5.10-lts
console output: https://syzkaller.appspot.com/x/log.txt?x=14523fce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a785e77f3e5809cd
dashboard link: https://syzkaller.appspot.com/bug?extid=5a4cb69d50e0f4dc32e9
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10596e36580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10b0602e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/779df7314d92/disk-1b323275.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a3b4dce5953d/vmlinux-1b323275.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b139d7e3bd87/bzImage-1b323275.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/57cdf5e83ce1/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17f91bce580000)
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/d9b20b32b294/mount_6.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=14e4e306580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5a4cb6...@syzkaller.appspotmail.com

EXT4-fs (loop2): Warning: mounting with an experimental mount option 'dioread_nolock' for blocksize < PAGE_SIZE
[EXT4 FS bs=1024, gc=1, bpg=131072, ipg=32, mo=e855c01c, mo2=0003]
System zones: 0-1, 3-36
EXT4-fs (loop2): mounted filesystem without journal. Opts: grpquota,delalloc,resuid=0x0000000000000000,debug,dioread_nolock,bsddf,nomblk_io_submit,noauto_da_alloc,,errors=continue
==================================================================
BUG: KASAN: use-after-free in ext4_get_inode_usage+0x3a1/0x520 fs/ext4/xattr.c:817
Read of size 4 at addr ffff888110dd0070 by task syz.2.17/368

CPU: 0 PID: 368 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
__dump_stack+0x21/0x24 lib/dump_stack.c:77
dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:435 [inline]
kasan_report+0xe2/0x130 mm/kasan/report.c:452
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
ext4_get_inode_usage+0x3a1/0x520 fs/ext4/xattr.c:817
__dquot_transfer+0x192/0x20d0 fs/quota/dquot.c:2017
dquot_transfer+0x2f1/0x460 fs/quota/dquot.c:2169
ext4_setattr+0x715/0x1950 fs/ext4/inode.c:5577
notify_change+0xab3/0xe40 fs/attr.c:410
chown_common+0x335/0x500 fs/open.c:675
do_fchownat+0x147/0x240 fs/open.c:705
__do_sys_chown fs/open.c:725 [inline]
__se_sys_chown fs/open.c:723 [inline]
__x64_sys_chown+0x82/0x90 fs/open.c:723
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f4ee0985e59
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:00007ffc58f1c7e8 EFLAGS: 00000246 ORIG_RAX: 000000000000005c
RAX: ffffffffffffffda RBX: 00007f4ee0bfefa0 RCX: 00007f4ee0985e59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000140
RBP: 00007f4ee0a1bd6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ee0bfefac R14: 00007f4ee0bfefa0 R15: 00007f4ee0bfefa0

The buggy address belongs to the page:
page:ffffea0004437400 refcount:0 mapcount:-128 mapping:0000000000000000 index:0xffff888110dd2000 pfn:0x110dd0
flags: 0x4000000000000000()
raw: 4000000000000000 ffffea0004437808 ffffea0004438c08 0000000000000000
raw: ffff888110dd2000 0000000000000004 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 104, ts 4360692680, free_ts 26296659818
set_page_owner include/linux/page_owner.h:35 [inline]
post_alloc_hook mm/page_alloc.c:2456 [inline]
prep_new_page+0x179/0x180 mm/page_alloc.c:2462
get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254
__alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384
alloc_slab_page mm/slub.c:-1 [inline]
allocate_slab mm/slub.c:1813 [inline]
new_slab+0x84/0x3f0 mm/slub.c:1874
new_slab_objects mm/slub.c:2632 [inline]
___slab_alloc+0x2a6/0x450 mm/slub.c:2796
__slab_alloc+0x63/0xa0 mm/slub.c:2836
slab_alloc_node mm/slub.c:2918 [inline]
slab_alloc mm/slub.c:2960 [inline]
kmem_cache_alloc_trace+0x1b0/0x2e0 mm/slub.c:2977
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:667 [inline]
kernfs_iop_get_link+0x66/0x600 fs/kernfs/symlink.c:136
vfs_readlink+0x179/0x3e0 fs/namei.c:4728
do_readlinkat+0x251/0x490 fs/stat.c:426
__do_sys_readlink fs/stat.c:447 [inline]
__se_sys_readlink fs/stat.c:444 [inline]
__x64_sys_readlink+0x7f/0x90 fs/stat.c:444
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
reset_page_owner include/linux/page_owner.h:28 [inline]
free_pages_prepare mm/page_alloc.c:1349 [inline]
__free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
free_the_page mm/page_alloc.c:5445 [inline]
__free_pages+0xd8/0x3b0 mm/page_alloc.c:5454
__free_slab+0xcf/0x190 mm/slub.c:1899
free_slab mm/slub.c:1914 [inline]
discard_slab mm/slub.c:1920 [inline]
unfreeze_partials+0x15f/0x190 mm/slub.c:2415
put_cpu_partial+0xc1/0x180 mm/slub.c:2451
__slab_free+0x2c9/0x3a0 mm/slub.c:3100
do_slab_free mm/slub.c:3196 [inline]
___cache_free+0x10e/0x130 mm/slub.c:3215
qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440
kasan_slab_alloc include/linux/kasan.h:244 [inline]
slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
slab_alloc_node mm/slub.c:2952 [inline]
slab_alloc mm/slub.c:2960 [inline]
__kmalloc+0x180/0x330 mm/slub.c:4034
kmalloc include/linux/slab.h:560 [inline]
kzalloc include/linux/slab.h:667 [inline]
fib_create_info+0x8f0/0x1fc0 net/ipv4/fib_semantics.c:1479
fib_table_insert+0xc2/0x1d70 net/ipv4/fib_trie.c:1170
fib_magic net/ipv4/fib_frontend.c:1107 [inline]
fib_add_ifaddr+0xa7c/0xfc0 net/ipv4/fib_frontend.c:1151

Memory state around the buggy address:
ffff888110dcff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888110dcff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888110dd0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888110dd0080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888110dd0100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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