KASAN: use-after-free Read in reiserfs_fill_super

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 17529385 Linux 4.14.213
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15a238f7500000
kernel config: https://syzkaller.appspot.com/x/.config?x=f94010bb59bd4675
dashboard link: https://syzkaller.appspot.com/bug?extid=207f085f52755723335c
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+207f08...@syzkaller.appspotmail.com

==================================================================
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 ffff88800df8b000 by task syz-executor.3/7136

CPU: 0 PID: 7136 Comm: syz-executor.3 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: 0033:0x460c6a
RSP: 002b:00007fb4f7f15a78 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb4f7f15b10 RCX: 0000000000460c6a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fb4f7f15ad0
RBP: 00007fb4f7f15ad0 R08: 00007fb4f7f15b10 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020011100

The buggy address belongs to the page:
page:ffffea000037e2c0 count:0 mapcount:0 mapping: (null) index:0x1
flags: 0xfff00000000000()
raw: 00fff00000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea000037a5a0 ffffea000037a420 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88800df8af00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88800df8af80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88800df8b000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88800df8b080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88800df8b100: 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: 17529385 Linux 4.14.213
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=16a58750d00000

kernel config: https://syzkaller.appspot.com/x/.config?x=f94010bb59bd4675
dashboard link: https://syzkaller.appspot.com/bug?extid=207f085f52755723335c
compiler: gcc (GCC) 10.1.0-syz 20200507

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15496f70d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12267400d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+207f08...@syzkaller.appspotmail.com

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
==================================================================

[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=125396f2d00000
start commit: 17529385 Linux 4.14.213
git tree: linux-4.14.y

kernel config: https://syzkaller.appspot.com/x/.config?x=f94010bb59bd4675
dashboard link: https://syzkaller.appspot.com/bug?extid=207f085f52755723335c

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15496f70d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12267400d00000

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