KASAN: use-after-free Read in search_by_entry_key (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 958e517f Linux 4.14.230
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12f354ded00000
kernel config: https://syzkaller.appspot.com/x/.config?x=cdbb0f19434a286f
dashboard link: https://syzkaller.appspot.com/bug?extid=42d685ccd71d27232b90
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15568d19d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=125470e5d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+42d685...@syzkaller.appspotmail.com

reiserfs: using flush barriers
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 rupasov hash to sort names
==================================================================
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+0xc7e/0xf50 fs/reiserfs/namei.c:164
Read of size 4 at addr ffff88808b9a6004 by task syz-executor314/7986

CPU: 0 PID: 7986 Comm: syz-executor314 Not tainted 4.14.230-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
kasan_report mm/kasan/report.c:409 [inline]
__asan_report_load_n_noabort+0x6b/0x80 mm/kasan/report.c:440
bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
search_by_entry_key+0xc7e/0xf50 fs/reiserfs/namei.c:164
reiserfs_find_entry.part.0+0x138/0x11e0 fs/reiserfs/namei.c:321
reiserfs_find_entry fs/reiserfs/namei.c:367 [inline]
reiserfs_lookup+0x1fd/0x400 fs/reiserfs/namei.c:367
lookup_real fs/namei.c:1555 [inline]
__lookup_hash fs/namei.c:1575 [inline]
__lookup_hash+0x1bb/0x270 fs/namei.c:1563
lookup_one_len+0x279/0x3a0 fs/namei.c:2539
reiserfs_lookup_privroot+0x92/0x270 fs/reiserfs/xattr.c:970
reiserfs_fill_super+0x1211/0x28c0 fs/reiserfs/super.c:2197
mount_bdev+0x2b3/0x360 fs/super.c:1134
mount_fs+0x92/0x2a0 fs/super.c:1237
vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
vfs_kern_mount fs/namespace.c:1036 [inline]
do_new_mount fs/namespace.c:2549 [inline]
do_mount+0xe53/0x2a00 fs/namespace.c:2879
SYSC_mount fs/namespace.c:3095 [inline]
SyS_mount+0xa8/0x120 fs/namespace.c:3072
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x44c95a
RSP: 002b:00007ffe5b400d98 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe5b400df0 RCX: 000000000044c95a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe5b400db0
RBP: 00007ffe5b400db0 R08: 00007ffe5b400df0 R09: 0000003400000000
R10: 0000000000208403 R11: 0000000000000286 R12: 0000000000000004
R13: 0000000000000003 R14: 0000000000000003 R15: 0000000000000004

The buggy address belongs to the page:
page:ffffea00022e6980 count:0 mapcount:0 mapping: (null) index:0x1
flags: 0xfff00000000000()
raw: 00fff00000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea00022e69e0 ffff8880ba42dac8 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808b9a5f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88808b9a5f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88808b9a6000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88808b9a6080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88808b9a6100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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