affs: Fix memory leaks

The node structure reference is being allocated but not freed if it
reaches the end of the function. If any of the hooks had returned
a non-zero value, then node would have been copied in to the context
reference, but otherwise node is not stored and should be freed.

Similarly, the call to grub_affs_create_node() replaces the allocated
memory in node with a newly allocated structure, leaking the existing
memory pointed by node.

Finally, when dir->parent is set, then we again replace node with newly
allocated memory, which seems unnecessary when we copy in the values
from dir->parent immediately after.

Fixes: CID 73759
Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/039-affs-Fix-memory-leaks.patch

diff --git a/grub-core/fs/affs.c b/grub-core/fs/affs.c
index 220b3712f2a5107e5208df803e3a2e471c87abf5..230e26af0f8d95520a0ab020274c5d9eda9e595b 100644 (file)
--- a/grub-core/fs/affs.c
+++ b/grub-core/fs/affs.c
@@ -400,12 +400,12 @@ grub_affs_iterate_dir (grub_fshelp_node_t dir,
 {
   unsigned int i;
   struct grub_affs_file file;
-  struct grub_fshelp_node *node = 0;
+  struct grub_fshelp_node *node, *orig_node;
   struct grub_affs_data *data = dir->data;
   grub_uint32_t *hashtable;
 
   /* Create the directory entries for `.' and `..'.  */
-  node = grub_zalloc (sizeof (*node));
+  node = orig_node = grub_zalloc (sizeof (*node));
   if (!node)
     return 1;
     
@@ -414,9 +414,6 @@ grub_affs_iterate_dir (grub_fshelp_node_t dir,
     return 1;
   if (dir->parent)
     {
-      node = grub_zalloc (sizeof (*node));
-      if (!node)
-       return 1;
       *node = *dir->parent;
       if (hook ("..", GRUB_FSHELP_DIR, node, hook_data))
        return 1;
@@ -456,17 +453,18 @@ grub_affs_iterate_dir (grub_fshelp_node_t dir,
 
          if (grub_affs_create_node (dir, hook, hook_data, &node, &hashtable,
                                     next, &file))
-           return 1;
+           {
+             /* Node has been replaced in function. */
+             grub_free (orig_node);
+             return 1;
+           }
 
          next = grub_be_to_cpu32 (file.next);
        }
     }
 
-  grub_free (hashtable);
-  return 0;
-
  fail:
-  grub_free (node);
+  grub_free (orig_node);
   grub_free (hashtable);
   return 0;
 }