KASAN: use-after-free Read in search_by_entry_key (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15cb9508080000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=b91428e0adf8831831d2
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17152c40080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=131af608080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b91428...@syzkaller.appspotmail.com

REISERFS (device loop0): journal params: device loop0, size 15748, journal first block 18, max trans len 1024, max batch 900, max commit age 0, max trans age 30
REISERFS (device loop0): checking transaction log (loop0)
REISERFS (device loop0): Using r5 hash to sort names
REISERFS (device loop0): using 3.5.x disk format
==================================================================
BUG: KASAN: use-after-free in bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
BUG: KASAN: use-after-free in search_by_entry_key+0xcda/0xf30 fs/reiserfs/namei.c:164
Read of size 4 at addr ffff88808c3f1014 by task syz-executor235/8108

CPU: 0 PID: 8108 Comm: syz-executor235 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load_n_noabort+0x8b/0xa0 mm/kasan/report.c:443
bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
search_by_entry_key+0xcda/0xf30 fs/reiserfs/namei.c:164
reiserfs_find_entry.part.0+0x142/0x1480 fs/reiserfs/namei.c:321
reiserfs_find_entry fs/reiserfs/namei.c:367 [inline]
reiserfs_lookup+0x24a/0x490 fs/reiserfs/namei.c:367
__lookup_slow+0x246/0x4a0 fs/namei.c:1672
lookup_one_len+0x163/0x190 fs/namei.c:2544
reiserfs_lookup_privroot+0x92/0x280 fs/reiserfs/xattr.c:970
reiserfs_fill_super+0x1f12/0x2d80 fs/reiserfs/super.c:2187
mount_bdev+0x2fc/0x3b0 fs/super.c:1158
mount_fs+0xa3/0x310 fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2492 [inline]
do_mount+0x115c/0x2f50 fs/namespace.c:2822
ksys_mount+0xcf/0x130 fs/namespace.c:3038
__do_sys_mount fs/namespace.c:3052 [inline]
__se_sys_mount fs/namespace.c:3049 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3049
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f8142fbfc8a
Code: 48 c7 c2 c0 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 a8 00 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc7acc0008 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc7acc0060 RCX: 00007f8142fbfc8a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffc7acc0020
RBP: 00007ffc7acc0020 R08: 00007ffc7acc0060 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 00000000200000a0
R13: 0000000000000003 R14: 0000000000000004 R15: 0000000000000004

The buggy address belongs to the page:
page:ffffea000230fc40 count:0 mapcount:0 mapping:0000000000000000 index:0x1
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea000230fc88 ffff8880ba02ea88 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808c3f0f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88808c3f0f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88808c3f1000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88808c3f1080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88808c3f1100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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