ext2fs: Trap trying to access bogus data areas

i.e. superblock, block group descriptor table or beyond the end.

1 files changed, 6 insertions, 1 deletions

diff --git a/ext2fs/getblk.c b/ext2fs/getblk.c
index 7c94d87f..26ac145e 100644
--- a/ext2fs/getblk.c
+++ b/ext2fs/getblk.c
@@ -130,7 +130,12 @@ inode_getblk (struct node *node, int nr, int create, int zero,
 
   *result = diskfs_node_disknode (node)->info.i_data[nr];
   if (*result)
-    return 0;
+    {
+      /* Trap trying to access superblock, block group descriptor table, or beyond the end */
+      assert_backtrace (*result >= group_desc_block_end
+		     && *result < store->size >> log2_block_size);
+      return 0;
+    }
 
   if (!create)
     return EINVAL;