Squashfs: add sanity checks to id reading at mount time

[deliverable/linux.git] / fs / squashfs / id.c

diff --git a/fs/squashfs/id.c b/fs/squashfs/id.c
index 2fdac6703b481e0db548b13649df3092464d15a3..499d08a1f34aead90bcb753881e2d93027ef2058 100644 (file)
--- a/fs/squashfs/id.c
+++ b/fs/squashfs/id.c
@@ -66,11 +66,37 @@ int squashfs_get_id(struct super_block *sb, unsigned int index,
  * Read uncompressed id lookup table indexes from disk into memory
  */
 __le64 *squashfs_read_id_index_table(struct super_block *sb,
-                       u64 id_table_start, unsigned short no_ids)
+               u64 id_table_start, u64 next_table, unsigned short no_ids)
 {
        unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
+       __le64 *table;
 
        TRACE("In read_id_index_table, length %d\n", length);
 
-       return squashfs_read_table(sb, id_table_start, length);
+       /* Sanity check values */
+
+       /* there should always be at least one id */
+       if (no_ids == 0)
+               return ERR_PTR(-EINVAL);
+
+       /*
+        * length bytes should not extend into the next table - this check
+        * also traps instances where id_table_start is incorrectly larger
+        * than the next table start
+        */
+       if (id_table_start + length > next_table)
+               return ERR_PTR(-EINVAL);
+
+       table = squashfs_read_table(sb, id_table_start, length);
+
+       /*
+        * table[0] points to the first id lookup table metadata block, this
+        * should be less than id_table_start
+        */
+       if (!IS_ERR(table) && table[0] >= id_table_start) {
+               kfree(table);
+               return ERR_PTR(-EINVAL);
+       }
+
+       return table;
 }