syzbot


KASAN: use-after-free Read in search_by_entry_key

Status: fixed on 2021/02/20 09:47
Reported-by: syzbot+1b84cc0519f482028eca@syzkaller.appspotmail.com
Fix commit: b8590c82b3cc reiserfs: add check for an invalid ih_entry_count
First crash: 787d, last: 697d

Fix bisection: fixed by (bisect log) :
commit b8590c82b3ccf9fb4d9f0b0b097be10736869333
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 (6):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in search_by_entry_key (2) C inconclusive inconclusive 14 11d 173d 0/24 upstream: reported C repro on 2022/06/12 10:38
linux-4.14 KASAN: use-after-free Read in search_by_entry_key (2) C error 5 11h24m 596d 0/1 upstream: reported C repro on 2021/04/16 06:17
linux-4.14 KASAN: use-after-free Read in search_by_entry_key C done 3 696d 802d 1/1 fixed on 2021/02/21 17:18
linux-4.19 KASAN: use-after-free Read in search_by_entry_key (3) C error 6 7d05h 169d 0/1 upstream: reported C repro on 2022/06/17 02:59
upstream KASAN: use-after-free Read in search_by_entry_key C done 3 782d 785d 21/24 fixed on 2021/03/10 01:49
linux-4.19 KASAN: use-after-free Read in search_by_entry_key (2) C done 2 478d 628d 1/1 fixed on 2021/09/10 21:17

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 bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
BUG: KASAN: use-after-free in search_by_entry_key+0xcf4/0xf50 fs/reiserfs/namei.c:164
Read of size 4 at addr ffff8880786f97bd by task syz-executor536/6501

CPU: 1 PID: 6501 Comm: syz-executor536 Not tainted 4.19.149-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+0x22c/0x33e lib/dump_stack.c:118
 print_address_description.cold+0x56/0x25c mm/kasan/report.c:256
 kasan_report_error.cold+0x66/0xb9 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+0xcf4/0xf50 fs/reiserfs/namei.c:164
 reiserfs_find_entry.part.0+0x143/0x1400 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:963
 reiserfs_fill_super+0x21e8/0x2e60 fs/reiserfs/super.c:2179
 mount_bdev+0x2fc/0x3b0 fs/super.c:1158
 mount_fs+0xa3/0x318 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:2469 [inline]
 do_mount+0x51c/0x2f10 fs/namespace.c:2799
 ksys_mount+0xcf/0x130 fs/namespace.c:3015
 __do_sys_mount fs/namespace.c:3029 [inline]
 __se_sys_mount fs/namespace.c:3026 [inline]
 __x64_sys_mount+0xba/0x150 fs/namespace.c:3026
 do_syscall_64+0xf9/0x670 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447d9a
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 7d a3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 5a a3 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffe22e07138 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe22e07190 RCX: 0000000000447d9a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe22e07150
RBP: 00007ffe22e07150 R08: 00007ffe22e07190 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000006
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

The buggy address belongs to the page:
page:ffffea0001e1be40 count:0 mapcount:0 mapping:0000000000000000 index:0x1
flags: 0xfffe0000000000()
raw: 00fffe0000000000 ffffea0001e1be88 ffffea0001e1be08 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880786f9680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880786f9700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880786f9780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                        ^
 ffff8880786f9800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880786f9880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-19 2020/10/06 18:06 linux-4.19.y b09c34517e1a 1880b4a9 .config log report syz C
* Struck through repros no longer work on HEAD.