2024-05-17 09:43:16

by Ferry Meng

Subject: [PATCH v2 1/2] ocfs2: add bounds checking to ocfs2_xattr_find_entry()

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 <[email protected]>
---
fs/ocfs2/xattr.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 3b81213ed7b8..8aea94c90739 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -1062,7 +1062,7 @@ ssize_t ocfs2_listxattr(struct dentry *dentry,
return i_ret + b_ret;
}

-static int ocfs2_xattr_find_entry(int name_index,
+static int ocfs2_xattr_find_entry(struct inode *inode, int name_index,
const char *name,
struct ocfs2_xattr_search *xs)
{
@@ -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 >= xs->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, 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, 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, name_index, name, xs);
} else
ret = ocfs2_xattr_index_block_find(inode, blk_bh,
name_index,
--
2.32.0.3.g01195cf9f

2024-05-17 10:52:52

by Joseph Qi

Subject: Re: [PATCH v2 1/2] ocfs2: add bounds checking to ocfs2_xattr_find_entry()

On 5/17/24 5:41 PM, Ferry Meng wrote:
> 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 <[email protected]>

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

> ---
> fs/ocfs2/xattr.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
> index 3b81213ed7b8..8aea94c90739 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -1062,7 +1062,7 @@ ssize_t ocfs2_listxattr(struct dentry *dentry,
> return i_ret + b_ret;
> }
>
> -static int ocfs2_xattr_find_entry(int name_index,
> +static int ocfs2_xattr_find_entry(struct inode *inode, int name_index,
> const char *name,
> struct ocfs2_xattr_search *xs)
> {
> @@ -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 >= xs->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, 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, 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, name_index, name, xs);
> } else
> ret = ocfs2_xattr_index_block_find(inode, blk_bh,
> name_index,