KASAN: use-after-free Read in reiserfs_fill_super

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b3298500 Merge tag 'for-5.10/dm-fixes' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e64345500000
kernel config: https://syzkaller.appspot.com/x/.config?x=e49433cfed49b7d9
dashboard link: https://syzkaller.appspot.com/bug?extid=2b5c012223e37b7c2a88
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12ad719b500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11193117500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2b5c01...@syzkaller.appspotmail.com

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:1325 [inline]
BUG: KASAN: use-after-free in reiserfs_read_locked_inode+0x1f2d/0x2230 fs/reiserfs/inode.c:1574
Read of size 4 at addr ffff888035a26000 by task syz-executor059/8481

CPU: 0 PID: 8481 Comm: syz-executor059 Not tainted 5.10.0-rc6-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+0x107/0x163 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
__kasan_report mm/kasan/report.c:545 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
init_inode fs/reiserfs/inode.c:1325 [inline]
reiserfs_read_locked_inode+0x1f2d/0x2230 fs/reiserfs/inode.c:1574
reiserfs_fill_super+0x18eb/0x2e00 fs/reiserfs/super.c:2081
mount_bdev+0x32e/0x3f0 fs/super.c:1419
legacy_get_tree+0x105/0x220 fs/fs_context.c:592
vfs_get_tree+0x89/0x2f0 fs/super.c:1549
do_new_mount fs/namespace.c:2875 [inline]
path_mount+0x13ad/0x20c0 fs/namespace.c:3205
do_mount fs/namespace.c:3218 [inline]
__do_sys_mount fs/namespace.c:3426 [inline]
__se_sys_mount fs/namespace.c:3403 [inline]
__x64_sys_mount+0x27f/0x300 fs/namespace.c:3403
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x447d7a
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:00007ffcf7e76348 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffcf7e763a0 RCX: 0000000000447d7a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffcf7e76360
RBP: 00007ffcf7e76360 R08: 00007ffcf7e763a0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000006
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

The buggy address belongs to the page:
page:0000000050546bce refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x35a26
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea0000d689c8 ffff8880b9e39d48 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888035a25f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888035a25f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888035a26000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888035a26080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888035a26100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit d24396c5290ba8ab04ba505176874c4e04a2d53c
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=113a2d57500000
start commit: b3298500 Merge tag 'for-5.10/dm-fixes' of git://git.kernel..
git tree: upstream

kernel config: https://syzkaller.appspot.com/x/.config?x=e49433cfed49b7d9
dashboard link: https://syzkaller.appspot.com/bug?extid=2b5c012223e37b7c2a88

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12ad719b500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11193117500000

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

[syzbot]

Your 'fix:' command is accepted, but please keep syzkall...@googlegroups.com mailing list in CC next time. It serves as a history of what happened with each bug report. Thank you.

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> SUSE Labs, CR