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SubjectRe: [PATCH 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry()
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On 5/15/24 9:29 PM, Ferry Meng wrote:
> xattr in ocfs2 maybe not INLINE, but saved with additional space
> requested. It's better to check if the memory is out of bound before
> memcmp, although this possibility mainly comes from custom poisonous
> images.

Specifically, this only addresses the case non-indexed xattr.

>
> Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
> ---
> fs/ocfs2/xattr.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
> index 37be4a286faf..4ceb0cb4cb71 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -1083,10 +1083,15 @@ static int ocfs2_xattr_find_entry(struct inode *inode, void *end,
> cmp = name_index - ocfs2_xattr_get_type(entry);

Or define a local variable 'offset' for le16_to_cpu(entry->xe_name_offset).

Thanks,
Joseph

> if (!cmp)
> cmp = name_len - entry->xe_name_len;
> - if (!cmp)
> + if (!cmp) {
> + if ((xs->base + le16_to_cpu(entry->xe_name_offset) + name_len) > end) {
> + ocfs2_error(inode->i_sb, "corrupted xattr entries");
> + return -EFSCORRUPTED;
> + }
> cmp = memcmp(name, (xs->base +
> le16_to_cpu(entry->xe_name_offset)),
> name_len);
> + }
> if (cmp == 0)
> break;
> entry += 1;

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