From: Joseph Qi <joseph.qi@linux.alibaba.com>
To: Ferry Meng <mengferry@linux.alibaba.com>,
Mark Fasheh <mark@fasheh.com>, Joel Becker <jlbec@evilplan.org>,
ocfs2-devel@lists.linux.dev
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] ocfs2: add bounds checking to ocfs2_xattr_find_entry()
Date: Thu, 16 May 2024 09:25:26 +0800 [thread overview]
Message-ID: <cb1d3df4-db34-447d-b265-e4fad5a1fe7f@linux.alibaba.com> (raw)
In-Reply-To: <20240515132934.69511-2-mengferry@linux.alibaba.com>
On 5/15/24 9:29 PM, Ferry Meng wrote:
> Just add redundant (perhaps paranoia) checks to make sure it doesn't
> stray beyond valid meory region of ocfs2 xattr entry array during a
> single match.
>
> Maybe this patch can prevent some crash caused by crafted poison images.
>
I'd rather restructure the commit message as below:
Add a paranoia check to make sure it doesn't stray beyond valid memory
region containing ocfs2 xattr entries when scanning for a match.
It will prevent out-of-bound access in case of crafted images.
> Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
> ---
> fs/ocfs2/xattr.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
> index 3b81213ed7b8..37be4a286faf 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -1062,8 +1062,8 @@ ssize_t ocfs2_listxattr(struct dentry *dentry,
> return i_ret + b_ret;
> }
>
> -static int ocfs2_xattr_find_entry(int name_index,
> - const char *name,
> +static int ocfs2_xattr_find_entry(struct inode *inode, void *end,
'end' can be obtained from ocfs2_xattr_search directly.
Thanks,
Joseph
> + int name_index, const char *name,
> struct ocfs2_xattr_search *xs)
> {
> struct ocfs2_xattr_entry *entry;
> @@ -1076,6 +1076,10 @@ static int ocfs2_xattr_find_entry(int name_index,
> name_len = strlen(name);
> entry = xs->here;
> for (i = 0; i < le16_to_cpu(xs->header->xh_count); i++) {
> + if ((void *)entry >= end) {
> + ocfs2_error(inode->i_sb, "corrupted xattr entries");
> + return -EFSCORRUPTED;
> + }
> cmp = name_index - ocfs2_xattr_get_type(entry);
> if (!cmp)
> cmp = name_len - entry->xe_name_len;
> @@ -1166,7 +1170,7 @@ static int ocfs2_xattr_ibody_get(struct inode *inode,
> xs->base = (void *)xs->header;
> xs->here = xs->header->xh_entries;
>
> - ret = ocfs2_xattr_find_entry(name_index, name, xs);
> + ret = ocfs2_xattr_find_entry(inode, xs->end, name_index, name, xs);
> if (ret)
> return ret;
> size = le64_to_cpu(xs->here->xe_value_size);
> @@ -2698,7 +2702,7 @@ static int ocfs2_xattr_ibody_find(struct inode *inode,
>
> /* Find the named attribute. */
> if (oi->ip_dyn_features & OCFS2_INLINE_XATTR_FL) {
> - ret = ocfs2_xattr_find_entry(name_index, name, xs);
> + ret = ocfs2_xattr_find_entry(inode, xs->end, name_index, name, xs);
> if (ret && ret != -ENODATA)
> return ret;
> xs->not_found = ret;
> @@ -2833,7 +2837,7 @@ static int ocfs2_xattr_block_find(struct inode *inode,
> xs->end = (void *)(blk_bh->b_data) + blk_bh->b_size;
> xs->here = xs->header->xh_entries;
>
> - ret = ocfs2_xattr_find_entry(name_index, name, xs);
> + ret = ocfs2_xattr_find_entry(inode, xs->end, name_index, name, xs);
> } else
> ret = ocfs2_xattr_index_block_find(inode, blk_bh,
> name_index,
next prev parent reply other threads:[~2024-05-16 1:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-15 13:29 [PATCH 0/2] ocfs2: add checks in ocfs2_xattr_find_entry() to avoid potential out-of-bound access Ferry Meng
2024-05-15 13:29 ` [PATCH 1/2] ocfs2: add bounds checking to ocfs2_xattr_find_entry() Ferry Meng
2024-05-16 1:25 ` Joseph Qi [this message]
2024-05-15 13:29 ` [PATCH 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry() Ferry Meng
2024-05-16 1:41 ` Joseph Qi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=cb1d3df4-db34-447d-b265-e4fad5a1fe7f@linux.alibaba.com \
--to=joseph.qi@linux.alibaba.com \
--cc=jlbec@evilplan.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark@fasheh.com \
--cc=mengferry@linux.alibaba.com \
--cc=ocfs2-devel@lists.linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).