From: "chenxiaosong (A)" <chenxiaosong2@huawei.com>
To: Hawkins Jiawei <yin31149@gmail.com>,
<syzbot+5f8dcabe4a3b2c51c607@syzkaller.appspotmail.com>,
Anton Altaparmakov <anton@tuxera.com>
Cc: <akpm@linux-foundation.org>, <linux-kernel@vger.kernel.org>,
<linux-ntfs-dev@lists.sourceforge.net>,
<syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH] ntfs: change check order in ntfs_attr_find
Date: Sat, 27 Aug 2022 09:28:51 +0800 [thread overview]
Message-ID: <1636796c-c85e-7f47-e96f-e074fee3c7d3@huawei.com> (raw)
In-Reply-To: <20220826122735.2690-1-yin31149@gmail.com>
在 2022/8/26 20:27, Hawkins Jiawei 写道:
> syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>
> Looks like it is improper check order that causes this bug.
>
> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
> ---
> fs/ntfs/attrib.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
> index 52615e6090e1..6480cd2d371d 100644
> --- a/fs/ntfs/attrib.c
> +++ b/fs/ntfs/attrib.c
> @@ -594,10 +594,11 @@ static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name,
> for (;; a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) {
> u8 *mrec_end = (u8 *)ctx->mrec +
> le32_to_cpu(ctx->mrec->bytes_allocated);
> + if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end)
> + break;
> u8 *name_end = (u8 *)a + le16_to_cpu(a->name_offset) +
> a->name_length * sizeof(ntfschar);
> - if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end ||
> - name_end > mrec_end)
> + if (name_end > mrec_end)
> break;
> ctx->attr = a;
> if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) ||
>
The reason is that a->length is 0, it will occur uaf when deref any
field of ATTR_RECORD.
It seems that changing check order will not fix root cause, if the
condition "if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end)" is false,
uaf will still occur.
Do you have any thoughts on this ?
next prev parent reply other threads:[~2022-08-27 1:32 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-25 18:25 [syzbot] KASAN: use-after-free Read in ntfs_attr_find syzbot
2022-08-25 18:32 ` Siddh Raman Pant
2022-08-25 18:34 ` Siddh Raman Pant
2022-08-26 12:27 ` [PATCH] ntfs: change check order " Hawkins Jiawei
2022-08-26 12:32 ` Hawkins Jiawei
2022-08-26 14:16 ` [syzbot] KASAN: use-after-free Read " syzbot
2022-08-26 15:15 ` [PATCH] ntfs: change check order " Dan Carpenter
2022-08-26 15:42 ` Hawkins Jiawei
2022-08-26 15:54 ` Hawkins Jiawei
2022-08-27 6:42 ` Dan Carpenter
2022-08-27 9:02 ` Hawkins Jiawei
2022-08-27 10:58 ` Dan Carpenter
2022-08-28 16:15 ` Hawkins Jiawei
2022-08-27 2:42 ` Andrew Morton
2022-08-27 8:38 ` Hawkins Jiawei
2022-08-27 1:28 ` chenxiaosong (A) [this message]
2022-08-27 7:51 ` Hawkins Jiawei
2022-08-27 14:49 ` Hawkins Jiawei
2022-08-29 9:51 ` Dan Carpenter
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