Squashfs: add extra sanity checks at mount time

Add some extra sanity checks of the inode and directory structures.

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

1 files changed, 16 insertions, 2 deletions

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index efa8118260d4..984d6c861928 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -268,7 +268,7 @@ allocate_id_index_table:
 handle_fragments:
         fragments = le32_to_cpu(sblk->fragments);
         if (fragments == 0)
-                goto allocate_root;
+                goto check_directory_table;
 
         msblk->fragment_cache = squashfs_cache_init("fragment",
                 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
@@ -286,8 +286,22 @@ handle_fragments:
                 msblk->fragment_index = NULL;
                 goto failed_mount;
         }
+        next_table = msblk->fragment_index[0];
 
-allocate_root:
+check_directory_table:
+        /* Sanity check directory_table */
+        if (msblk->directory_table >= next_table) {
+                err = -EINVAL;
+                goto failed_mount;
+        }
+
+        /* Sanity check inode_table */
+        if (msblk->inode_table >= msblk->directory_table) {
+                err = -EINVAL;
+                goto failed_mount;
+        }
+
+        /* allocate root */
         root = new_inode(sb);
         if (!root) {
                 err = -ENOMEM;