Squashfs: add sanity checks to lookup table reading at mount time

[pandora-kernel.git] / fs / squashfs / export.c

diff --git a/fs/squashfs/export.c b/fs/squashfs/export.c
index cc6dd90..e310871 100644 (file)
--- a/fs/squashfs/export.c
+++ b/fs/squashfs/export.c
@@ -121,13 +121,38 @@ static struct dentry *squashfs_get_parent(struct dentry *child)
  * Read uncompressed inode lookup table indexes off disk into memory
  */
 __le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
-               u64 lookup_table_start, unsigned int inodes)
+               u64 lookup_table_start, u64 next_table, unsigned int inodes)
 {
        unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
+       __le64 *table;
 
        TRACE("In read_inode_lookup_table, length %d\n", length);
 
-       return squashfs_read_table(sb, lookup_table_start, length);
+       /* Sanity check values */
+
+       /* there should always be at least one inode */
+       if (inodes == 0)
+               return ERR_PTR(-EINVAL);
+
+       /* length bytes should not extend into the next table - this check
+        * also traps instances where lookup_table_start is incorrectly larger
+        * than the next table start
+        */
+       if (lookup_table_start + length > next_table)
+               return ERR_PTR(-EINVAL);
+
+       table = squashfs_read_table(sb, lookup_table_start, length);
+
+       /*
+        * table[0] points to the first inode lookup table metadata block,
+        * this should be less than lookup_table_start
+        */
+       if (!IS_ERR(table) && table[0] >= lookup_table_start) {
+               kfree(table);
+               return ERR_PTR(-EINVAL);
+       }
+
+       return table;
 }