linux-kernel - Bug: use-after-free in __bitmap

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Message-Id: <630B5C8C-5C8A-4BFB-9FB0-A63CDB200629@m.fudan.edu.cn>
Date: Tue, 24 Dec 2024 19:37:29 +0800
From: Kun Hu <huk23@...udan.edu.cn>
To: akpm@...ux-foundation.org,
 yury.norov@...il.com,
 linux@...musvillemoes.dk,
 pabeni@...hat.com,
 jacob.e.keller@...el.com
Cc: linux-kernel@...r.kernel.org,
 "jjtan24@...udan.edu.cn" <jjtan24@...udan.edu.cn>
Subject: Bug: use-after-free in __bitmap_weight

Hello,

When using fuzzer tool to fuzz the latest Linux kernel, the following crash
was triggered.

HEAD commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
git tree: upstream
Console output: https://drive.google.com/file/d/1CJ3VaQxlqkGdcEitM_aoSuzeCpfUWrAi/view?usp=sharing
Kernel config: https://drive.google.com/file/d/1RhT5dFTs6Vx1U71PbpenN7TPtnPoa3NI/view?usp=sharing
C reproducer: /
Syzlang reproducer: /


Unfortunately, we're getting a stable reproduction of the program. If you fix this issue, please add the following tag to the commit:
Reported-by: Kun Hu <huk23@...udan.edu.cn>

(syz.0.394,3922,2):ocfs2_mknod:298 ERROR: status = -2
(syz.0.394,3922,2):ocfs2_mknod:502 ERROR: status = -2
(syz.0.394,3922,2):ocfs2_create:676 ERROR: status = -2
==================================================================
BUG: KASAN: use-after-free in __bitmap_weight+0xf9/0x110 lib/bitmap.c:340
Read of size 8 at addr ff11000056367000 by task syz.0.394/3922

CPU: 2 UID: 0 PID: 3922 Comm: syz.0.394 Not tainted 6.13.0-rc3 #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcf/0x5f0 mm/kasan/report.c:489
kasan_report+0x93/0xc0 mm/kasan/report.c:602
__bitmap_weight+0xf9/0x110 lib/bitmap.c:340
bitmap_weight include/linux/bitmap.h:446 [inline]
memweight+0x120/0x1c0 lib/memweight.c:24
ocfs2_local_alloc_count_bits fs/ocfs2/localalloc.c:817 [inline]
ocfs2_reserve_local_alloc_bits+0x3e1/0x10a0 fs/ocfs2/localalloc.c:655
ocfs2_reserve_clusters_with_limit+0x7eb/0xcd0 fs/ocfs2/suballoc.c:1166
ocfs2_reserve_clusters fs/ocfs2/suballoc.c:1227 [inline]
ocfs2_lock_allocators+0x351/0x610 fs/ocfs2/suballoc.c:2746
ocfs2_extend_allocation+0x274/0x17d0 fs/ocfs2/file.c:589
ocfs2_allocate_unwritten_extents+0x22c/0x740 fs/ocfs2/file.c:1496
__ocfs2_change_file_space+0xba0/0x1090 fs/ocfs2/file.c:2023
ocfs2_fallocate+0x271/0x300 fs/ocfs2/file.c:2138
vfs_fallocate+0x49d/0xeb0 fs/open.c:327
ksys_fallocate+0x55/0xa0 fs/open.c:351
__do_sys_fallocate fs/open.c:356 [inline]
__se_sys_fallocate fs/open.c:354 [inline]
__x64_sys_fallocate+0x97/0x100 fs/open.c:354
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc3/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9d68c8d71d
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9d678bfba8 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f9d68e50058 RCX: 00007f9d68c8d71d
RDX: 00000000000000fa RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f9d68d02425 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000ffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9d68e50064 R14: 00007f9d68e500f0 R15: 00007f9d678bfd40
</TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7f pfn:0x56367
flags: 0x100000000000000(node=0|zone=1)
raw: 0100000000000000 ffd4000001221708 ffd40000012ea688 0000000000000000
raw: 000000000000007f 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ff11000056366f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ff11000056366f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ff11000056367000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ff11000056367080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff11000056367100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
OCFS2: ERROR (device loop0): ocfs2_reserve_local_alloc_bits: local alloc inode 10712166395476743305 says it has 2419393108 used bits, but a count shows 145657
On-disk corruption discovered. Please run fsck.ocfs2 once the filesystem is unmounted.
OCFS2: Returning error to the calling process.
(syz.0.394,3922,2):ocfs2_reserve_local_alloc_bits:710 ERROR: status = -5
(syz.0.394,3922,2):ocfs2_reserve_clusters_with_limit:1170 ERROR: status = -5
(syz.0.394,3922,2):ocfs2_reserve_clusters_with_limit:1219 ERROR: status = -5
(syz.0.394,3922,2):ocfs2_lock_allocators:2749 ERROR: status = -5
(syz.0.394,3922,2):ocfs2_extend_allocation:592 ERROR: status = -5
(syz.0.394,3922,2):ocfs2_allocate_unwritten_extents:1499 ERROR: status = -5
(syz.0.394,3922,2):__ocfs2_change_file_space:2045 ERROR: status = -5


---------------
thanks,
Kun Hu