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.

Link: https://lkml.kernel.org/r/20240520024024.1976129-1-joseph.qi@linux.alibaba.com
Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reported-by: lei lu <llfamsec@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 3b81213ed7b85bbfd227f6c902fb4d749d0d8c48..8aea94c907397948c371573448b9d3b9d312f970 100644 (file)
--- 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,