Squashfs: add sanity checks to xattr reading at mount time

These checks add sanity checking of the mount-time xattr structures.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/squashfs/xattr_id.c b/fs/squashfs/xattr_id.c
index 51a7bd0cc449..f60fb3cce183 100644
--- a/fs/squashfs/xattr_id.c
+++ b/fs/squashfs/xattr_id.c
@@ -76,6 +76,17 @@ __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
         *xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
         *xattr_ids = le32_to_cpu(id_table->xattr_ids);
         kfree(id_table);
+
+        /* Sanity check values */
+
+        /* there is always at least one xattr id */
+        if (*xattr_ids == 0)
+                return ERR_PTR(-EINVAL);
+
+        /* xattr_table should be less than start */
+        if (*xattr_table_start >= start)
+                return ERR_PTR(-EINVAL);
+
         len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
 
         TRACE("In read_xattr_index_table, length %d\n", len);