syzbot


KASAN: use-after-free Read in reiserfs_fill_super
Status: fixed on 2021/02/21 17:18
Reported-by: syzbot+207f085f52755723335c@syzkaller.appspotmail.com
Fix commit: b74d5f70523a reiserfs: add check for an invalid ih_entry_count
First crash: 504d, last: 504d

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 (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in reiserfs_fill_super C error done 2 534d 533d 21/22 fixed on 2021/03/10 01:48
upstream KASAN: use-after-free Read in reiserfs_fill_super (2) 1 170d 166d 0/22 auto-closed as invalid on 2022/02/03 07:30

Sample crash report:
reiserfs: using flush barriers
REISERFS (device loop0): journal params: device loop0, size 8192, 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)
==================================================================
BUG: KASAN: use-after-free in init_inode fs/reiserfs/inode.c:1326 [inline]
BUG: KASAN: use-after-free in reiserfs_read_locked_inode+0x2030/0x2190 fs/reiserfs/inode.c:1575
Read of size 4 at addr ffff8880876c5000 by task syz-executor847/7983

CPU: 1 PID: 7983 Comm: syz-executor847 Not tainted 4.14.213-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 mm/kasan/report.c:409 [inline]
 __asan_report_load_n_noabort+0x6b/0x80 mm/kasan/report.c:440
 init_inode fs/reiserfs/inode.c:1326 [inline]
 reiserfs_read_locked_inode+0x2030/0x2190 fs/reiserfs/inode.c:1575
 reiserfs_fill_super+0x151f/0x28be fs/reiserfs/super.c:2084
 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: 0033:0x446dda
RSP: 002b:00007ffdc0dc1258 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffdc0dc12b0 RCX: 0000000000446dda
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffdc0dc1270
RBP: 00007ffdc0dc1270 R08: 00007ffdc0dc12b0 R09: 00007ffd00000015
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000006
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

The buggy address belongs to the page:
page:ffffea00021db140 count:0 mapcount:0 mapping:          (null) index:0x1
flags: 0xfff00000000000()
raw: 00fff00000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea00021db1a0 ffff8880ba52dac8 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880876c4f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880876c4f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880876c5000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8880876c5080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880876c5100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2021/01/05 18:09 linux-4.14.y 1752938529c6 a0234d98 .config log report syz C
ci2-linux-4-14 2021/01/05 17:54 linux-4.14.y 1752938529c6 a0234d98 .config log report info