2024-05-17 09:43:21

by Ferry Meng

Subject: [PATCH v2 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry()

xattr in ocfs2 maybe 'non-indexed', which 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 crafted poisonous
images.

Signed-off-by: Ferry Meng <[email protected]>
---
fs/ocfs2/xattr.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 8aea94c90739..35c0cc2a51af 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -1068,7 +1068,7 @@ static int ocfs2_xattr_find_entry(struct inode *inode, int name_index,
{
struct ocfs2_xattr_entry *entry;
size_t name_len;
- int i, cmp = 1;
+ int i, name_offset, cmp = 1;

if (name == NULL)
return -EINVAL;
@@ -1083,10 +1083,15 @@ static int ocfs2_xattr_find_entry(struct inode *inode, int name_index,
cmp = name_index - ocfs2_xattr_get_type(entry);
if (!cmp)
cmp = name_len - entry->xe_name_len;
- if (!cmp)
- cmp = memcmp(name, (xs->base +
- le16_to_cpu(entry->xe_name_offset)),
- name_len);
+ if (!cmp) {
+ name_offset = le16_to_cpu(entry->xe_name_offset);
+ if ((xs->base + name_offset + name_len) > xs->end) {
+ ocfs2_error(inode->i_sb,
+ "corrupted xattr entries");
+ return -EFSCORRUPTED;
+ }
+ cmp = memcmp(name, (xs->base + name_offset), name_len);
+ }
if (cmp == 0)
break;
entry += 1;
--
2.32.0.3.g01195cf9f

2024-05-17 10:53:40

by Joseph Qi

Subject: Re: [PATCH v2 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry()

On 5/17/24 5:41 PM, Ferry Meng wrote:
> xattr in ocfs2 maybe 'non-indexed', which 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 crafted poisonous
> images.
>
> Signed-off-by: Ferry Meng <[email protected]>

Reported-by: lei lu <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>

> ---
> fs/ocfs2/xattr.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
> index 8aea94c90739..35c0cc2a51af 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -1068,7 +1068,7 @@ static int ocfs2_xattr_find_entry(struct inode *inode, int name_index,
> {
> struct ocfs2_xattr_entry *entry;
> size_t name_len;
> - int i, cmp = 1;
> + int i, name_offset, cmp = 1;
>
> if (name == NULL)
> return -EINVAL;
> @@ -1083,10 +1083,15 @@ static int ocfs2_xattr_find_entry(struct inode *inode, int name_index,
> cmp = name_index - ocfs2_xattr_get_type(entry);
> if (!cmp)
> cmp = name_len - entry->xe_name_len;
> - if (!cmp)
> - cmp = memcmp(name, (xs->base +
> - le16_to_cpu(entry->xe_name_offset)),
> - name_len);
> + if (!cmp) {
> + name_offset = le16_to_cpu(entry->xe_name_offset);
> + if ((xs->base + name_offset + name_len) > xs->end) {
> + ocfs2_error(inode->i_sb,
> + "corrupted xattr entries");
> + return -EFSCORRUPTED;
> + }
> + cmp = memcmp(name, (xs->base + name_offset), name_len);
> + }
> if (cmp == 0)
> break;
> entry += 1;

2024-05-28 11:38:53

by lei lu

Subject: Re: [PATCH v2 2/2] ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry()

Hi,

Maybe we should add the same check for ocfs2_xattr_list_entries.