KASAN: use-after-free Read in leaf_paste

KASAN: use-after-free Read in leaf_paste_entries
Status: fixed on 2021/01/26 16:42
Reported-by: syzbot+a8a2ffc09ae509f0a7ba@syzkaller.appspotmail.com
Fix commit: b74d5f70523a reiserfs: add check for an invalid ih_entry_count
First crash: 552d, last: 508d

Fix bisection: fixed by (bisect log) :
commit b74d5f70523a819aac71e0eee4f4b530e69e463a
Author: Rustam Kovhaev <rkovhaev@gmail.com>
Date: Sun Nov 1 14:09:58 2020 +0000

reiserfs: add check for an invalid ih_entry_count

similar bugs (3):
Kernel	Title	Repro	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.19	KASAN: out-of-bounds Read in leaf_paste_entries	C	error	12	24d	549d	0/1	upstream: reported C repro on 2020/11/14 23:23
linux-4.19	KASAN: use-after-free Read in leaf_paste_entries	C	done	1	514d	514d	1/1	fixed on 2021/01/19 18:33
linux-4.14	KASAN: out-of-bounds Read in leaf_paste_entries	C	error	9	136d	589d	0/1	upstream: reported C repro on 2020/10/05 14:11

Sample crash report:

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 ffff8880839eb9bf by task syz-executor691/8006

CPU: 0 PID: 8006 Comm: syz-executor691 Not tainted 4.14.209-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: 0033:0x44706a
RSP: 002b:00007ffd8d257f68 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd8d257fc0 RCX: 000000000044706a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffd8d257f80
RBP: 00007ffd8d257f80 R08: 00007ffd8d257fc0 R09: 00007ffd00000015
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000006
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

The buggy address belongs to the page:
page:ffffea00020e7ac0 count:0 mapcount:0 mapping:          (null) index:0x1
flags: 0xfff00000000000()
raw: 00fff00000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea00020e7b20 ffff8880ba42dac8 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880839eb880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880839eb900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880839eb980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                        ^
 ffff8880839eba00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880839eba80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info
ci2-linux-4-14	2020/11/29 16:27	linux-4.14.y	87335852c5d9	a0092f9d	.config	log	report	syz	C
ci2-linux-4-14	2020/11/25 06:32	linux-4.14.y	87335852c5d9	1a1f4bd8	.config	log	report	syz	C
ci2-linux-4-14	2020/12/26 04:14	linux-4.14.y	3f2ecb86cb90	821e0b09	.config	log	report			info
ci2-linux-4-14	2020/12/01 00:13	linux-4.14.y	87335852c5d9	b3a34598	.config	log	report			info
ci2-linux-4-14	2020/11/25 05:03	linux-4.14.y	87335852c5d9	1a1f4bd8	.config	log	report			info
ci2-linux-4-14	2020/11/12 10:47	linux-4.14.y	27ce4f2a6817	77a55c8e	.config	log	report			info