[v6.1] KASAN: use-after-free Read in do_split

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7c15117f9468 Linux 6.1.115
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15fd3f40580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c9c0221b8515082d
dashboard link: https://syzkaller.appspot.com/bug?extid=232819123659561f765c
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d43a49ab45a4/disk-7c15117f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1169a6dd6d5/vmlinux-7c15117f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cac0c99432c7/bzImage-7c15117f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+232819...@syzkaller.appspotmail.com

EXT4-fs error (device loop2): ext4_xattr_ibody_find:2186: inode #15: comm syz.2.69: corrupted in-inode xattr
EXT4-fs error (device loop2): ext4_orphan_get:1405: comm syz.2.69: couldn't read orphan inode 15 (err -117)
EXT4-fs (loop2): mounted filesystem without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: use-after-free in dx_insert_block fs/ext4/namei.c:1387 [inline]
BUG: KASAN: use-after-free in do_split+0x1f3d/0x24f0 fs/ext4/namei.c:2080
Read of size 106000 at addr ffff888075192428 by task syz.2.69/4649

CPU: 0 PID: 4649 Comm: syz.2.69 Not tainted 6.1.115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15f/0x4f0 mm/kasan/report.c:395
kasan_report+0x136/0x160 mm/kasan/report.c:495
kasan_check_range+0x27f/0x290 mm/kasan/generic.c:189
memmove+0x25/0x60 mm/kasan/shadow.c:54
dx_insert_block fs/ext4/namei.c:1387 [inline]
do_split+0x1f3d/0x24f0 fs/ext4/namei.c:2080
make_indexed_dir+0xeaf/0x1590 fs/ext4/namei.c:2392
ext4_add_entry+0xd5d/0x1010 fs/ext4/namei.c:2504
ext4_rename fs/ext4/namei.c:3976 [inline]
ext4_rename2+0x26bc/0x4420 fs/ext4/namei.c:4258
vfs_rename+0xd32/0x10f0 fs/namei.c:4874
do_renameat2+0xde0/0x1440 fs/namei.c:5027
__do_sys_rename fs/namei.c:5073 [inline]
__se_sys_rename fs/namei.c:5071 [inline]
__x64_sys_rename+0x82/0x90 fs/namei.c:5071
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f710897e719
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:00007f71097e3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f7108b35f80 RCX: 00007f710897e719
RDX: 0000000000000000 RSI: 0000000020001c40 RDI: 0000000020000f40
RBP: 00007f71089f139e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7108b35f80 R15: 00007ffda7991378
</TASK>

The buggy address belongs to the physical page:
page:ffffea0001d46480 refcount:3 mapcount:1 mapping:ffff8880180828f8 index:0x3 pfn:0x75192
memcg:ffff888029424000
aops:def_blk_aops ino:700002
flags: 0xfff5800002205e(referenced|uptodate|dirty|lru|workingset|private|mappedtodisk|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff5800002205e ffffea000173a348 ffffea0001fe0b48 ffff8880180828f8
raw: 0000000000000003 ffff888058dcdcb0 0000000300000000 ffff888029424000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x148c40(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 4649, tgid 4647 (syz.2.69), ts 99882669151, free_ts 99570180601
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2517
prep_new_page mm/page_alloc.c:2524 [inline]
get_page_from_freelist+0x322e/0x33b0 mm/page_alloc.c:4290
__alloc_pages+0x28d/0x770 mm/page_alloc.c:5558
folio_alloc+0x1a/0x50 mm/mempolicy.c:2292
filemap_alloc_folio+0xda/0x4f0 mm/filemap.c:999
__filemap_get_folio+0x749/0xe80 mm/filemap.c:1993
pagecache_get_page+0x28/0x250 mm/folio-compat.c:110
find_or_create_page include/linux/pagemap.h:646 [inline]
grow_dev_page fs/buffer.c:946 [inline]
grow_buffers fs/buffer.c:1011 [inline]
__getblk_slow fs/buffer.c:1038 [inline]
__getblk_gfp+0x211/0xa20 fs/buffer.c:1333
sb_getblk_gfp include/linux/buffer_head.h:363 [inline]
ext4_sb_breadahead_unmovable+0x63/0xe0 fs/ext4/super.c:257
__ext4_get_inode_loc+0xbbb/0xe40 fs/ext4/inode.c:4594
__ext4_get_inode_loc_noinmem fs/ext4/inode.c:4624 [inline]
__ext4_iget+0x4ff/0x3ee0 fs/ext4/inode.c:4846
__ext4_fill_super fs/ext4/super.c:5400 [inline]
ext4_fill_super+0x6cb9/0x8b50 fs/ext4/super.c:5665
get_tree_bdev+0x3fe/0x620 fs/super.c:1366
vfs_get_tree+0x88/0x270 fs/super.c:1573
do_new_mount+0x2ba/0xb40 fs/namespace.c:3056
do_mount fs/namespace.c:3399 [inline]
__do_sys_mount fs/namespace.c:3607 [inline]
__se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3584
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1444 [inline]
free_pcp_prepare mm/page_alloc.c:1494 [inline]
free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3369
free_unref_page+0x33/0x3e0 mm/page_alloc.c:3464
__vunmap+0x834/0x9a0 mm/vmalloc.c:2717
free_work+0x57/0x80 mm/vmalloc.c:97
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
ffff888075192f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888075192f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888075193000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888075193080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
ffff888075193100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.