From: Hawkins Jiawei <yin31149@gmail.com>
To: chenxiaosong2@huawei.com
Cc: akpm@linux-foundation.org, anton@tuxera.com,
linux-kernel@vger.kernel.org,
linux-ntfs-dev@lists.sourceforge.net, liuyongqiang13@huawei.com,
yi.zhang@huawei.com, zhangxiaoxu5@huawei.com,
18801353760@163.com, skhan@linuxfoundation.org,
paskripkin@gmail.com,
linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH v2] ntfs: fix use-after-free in ntfs_ucsncmp()
Date: Sat, 9 Jul 2022 08:54:51 +0800 [thread overview]
Message-ID: <20220709005450.2220-1-yin31149@gmail.com> (raw)
In-Reply-To: <20220707105329.4020708-1-chenxiaosong2@huawei.com>
> Fix this by adding sanity check on end address of attibute name string.
> diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
> index 4de597a83b88..9ab8766872d2 100644
> --- a/fs/ntfs/attrib.c
> +++ b/fs/ntfs/attrib.c
> @@ -592,8 +592,12 @@ static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name,
> a = (ATTR_RECORD*)((u8*)ctx->attr +
> le32_to_cpu(ctx->attr->length));
> for (;; a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) {
> - if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
> - le32_to_cpu(ctx->mrec->bytes_allocated))
> + u8 *mrec_end = (u8 *)ctx->mrec +
> + le32_to_cpu(ctx->mrec->bytes_allocated);
> + u8 *name_end = (u8 *)a + le16_to_cpu(a->name_offset) +
> + a->name_length;
In my opinion, name_length field just means the number of characters,
yet each character is a ntfschar type. So name should be
name_length * sizeof(ntfschar) bytes. The example is at
https://elixir.bootlin.com/linux/v5.19-rc5/source/fs/ntfs/attrib.c#L1667
> + if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end ||
> + name_end > mrec_end)
> break;
> ctx->attr = a;
> if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) ||
> --
next prev parent reply other threads:[~2022-07-09 0:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 10:53 ChenXiaoSong
2022-07-09 0:54 ` Hawkins Jiawei [this message]
2022-07-09 3:14 ` chenxiaosong (A)
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