KASAN: use-after-free Read in leaf_paste_entries

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 27ce4f2a Linux 4.14.206
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12fb68f6500000
kernel config: https://syzkaller.appspot.com/x/.config?x=32258a0e1fac372d
dashboard link: https://syzkaller.appspot.com/bug?extid=a8a2ffc09ae509f0a7ba
compiler: gcc (GCC) 10.1.0-syz 20200507

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a8a2ff...@syzkaller.appspotmail.com

NILFS (loop1): unrecognized mount option "�=�� _�"
REISERFS (device loop2): Using tea hash to sort names
EXT4-fs: failed to create workqueue
EXT4-fs (loop0): mount failed
==================================================================
BUG: KASAN: use-after-free in memmove include/linux/string.h:387 [inline]
BUG: KASAN: use-after-free in leaf_paste_entries+0x421/0x9b0 fs/reiserfs/lbalance.c:1369
Read of size 18446744073709519376 at addr ffff888051d0dda4 by task syz-executor.2/2146

CPU: 1 PID: 2146 Comm: syz-executor.2 Not tainted 4.14.206-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+0x1b2/0x283 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
kasan_report+0x6f/0x7b mm/kasan/report.c:409
memmove+0x20/0x50 mm/kasan/kasan.c:293
memmove include/linux/string.h:387 [inline]
leaf_paste_entries+0x421/0x9b0 fs/reiserfs/lbalance.c:1369
balance_leaf_finish_node_paste_dirent fs/reiserfs/do_balan.c:1306 [inline]
balance_leaf_finish_node_paste fs/reiserfs/do_balan.c:1332 [inline]
balance_leaf_finish_node fs/reiserfs/do_balan.c:1375 [inline]
balance_leaf+0x8298/0xbaa0 fs/reiserfs/do_balan.c:1463
do_balance+0x27e/0x630 fs/reiserfs/do_balan.c:1899
reiserfs_paste_into_item+0x569/0x6f0 fs/reiserfs/stree.c:2142
reiserfs_add_entry+0x7d3/0xbc0 fs/reiserfs/namei.c:566
reiserfs_mkdir+0x5ca/0x8b0 fs/reiserfs/namei.c:858
create_privroot fs/reiserfs/xattr.c:880 [inline]
reiserfs_xattr_init+0x393/0xa49 fs/reiserfs/xattr.c:1002
reiserfs_fill_super+0x1b18/0x28be fs/reiserfs/super.c:2180
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: 0033:0x46090a
RSP: 002b:00007fa53786aa88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fa53786ab20 RCX: 000000000046090a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fa53786aae0
RBP: 00007fa53786aae0 R08: 00007fa53786ab20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020011500

The buggy address belongs to the page:
page:ffffea0001474340 count:0 mapcount:0 mapping: (null) index:0x1
flags: 0xfff00000000000()
raw: 00fff00000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea00012aa8e0 ffffea00014743e0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888051d0dc80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888051d0dd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888051d0dd80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888051d0de00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888051d0de80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 87335852 Linux 4.14.209
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13f6c295500000
kernel config: https://syzkaller.appspot.com/x/.config?x=77df3f7a7cfbd2e6

dashboard link: https://syzkaller.appspot.com/bug?extid=a8a2ffc09ae509f0a7ba
compiler: gcc (GCC) 10.1.0-syz 20200507

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1089aa79500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15953195500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a8a2ff...@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 30, 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 memmove include/linux/string.h:387 [inline]
BUG: KASAN: use-after-free in leaf_paste_entries+0x421/0x9b0 fs/reiserfs/lbalance.c:1369

Read of size 18446744073709549059 at addr ffff8880835179bf by task syz-executor427/7983

CPU: 1 PID: 7983 Comm: syz-executor427 Not tainted 4.14.209-syzkaller #0

RIP: 0033:0x44706a
RSP: 002b:00007ffe53434408 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe53434460 RCX: 000000000044706a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe53434420
RBP: 00007ffe53434420 R08: 00007ffe53434460 R09: 00007ffe00000015
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000006
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

The buggy address belongs to the page:

page:ffffea00020d45c0 count:0 mapcount:0 mapping: (null) index:0x1

flags: 0xfff00000000000()
raw: 00fff00000000000 0000000000000000 0000000000000001 00000000ffffffff

raw: ffffea00020d4620 ffff8880ba52dac8 0000000000000000 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff888083517880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888083517900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888083517980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888083517a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888083517a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

[syzbot]

syzbot suspects this issue was fixed by commit:

commit b74d5f70523a819aac71e0eee4f4b530e69e463a
Author: Rustam Kovhaev <rkov...@gmail.com>
Date: Sun Nov 1 14:09:58 2020 +0000

reiserfs: add check for an invalid ih_entry_count

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14d85794d00000
start commit: 87335852 Linux 4.14.209
git tree: linux-4.14.y
kernel config: https://syzkaller.appspot.com/x/.config?x=a932ed2a762225b
dashboard link: https://syzkaller.appspot.com/bug?extid=a8a2ffc09ae509f0a7ba
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113afae9500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17a76cc9500000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: reiserfs: add check for an invalid ih_entry_count

For information about bisection process see: https://goo.gl/tpsmEJ#bisection