[ostree] repo: Validate checksums have correct length

[Matthew Barnes <mbarnes src gnome org>]

commit 5307af5a7adc79af331c6da804c0ea75cb6adf22
Author: Matthew Barnes <mbarnes redhat com>
Date:   Mon Nov 16 19:29:59 2015 -0500

    repo: Validate checksums have correct length
    
    ostree_checksum_bytes_peek() can return NULL if the checksum has an
    incorrect length (most likely from disk corruption) but most callers
    are not prepared to handle this and would likely crash.
    
    Use ostree_checksum_bytes_peek_validate() instead, which sets a
    GError on an invalid checksum.

 src/libostree/ostree-repo-file.c |   18 +++++++++++---
 src/libostree/ostree-repo-pull.c |   49 +++++++++++++++++++++++++++++--------
 src/libostree/ostree-repo-refs.c |    9 +++++-
 3 files changed, 59 insertions(+), 17 deletions(-)
---
diff --git a/src/libostree/ostree-repo-file.c b/src/libostree/ostree-repo-file.c
index b382dbf..49f7333 100644
--- a/src/libostree/ostree-repo-file.c
+++ b/src/libostree/ostree-repo-file.c
@@ -869,9 +869,14 @@ ostree_repo_file_tree_query_child (OstreeRepoFile  *self,
   c = g_variant_n_children (files_variant);
   if (n < c)
     {
+      const guchar *csum_bytes;
+
       g_variant_get_child (files_variant, n, "(&s ay)", &name, &content_csum_v);
-      ostree_checksum_inplace_from_bytes (ostree_checksum_bytes_peek (content_csum_v),
-                                          tmp_checksum);
+      csum_bytes = ostree_checksum_bytes_peek_validate (content_csum_v, error);
+      if (csum_bytes == NULL)
+        goto out;
+
+      ostree_checksum_inplace_from_bytes (csum_bytes, tmp_checksum);
 
       if (!ostree_repo_load_file (self->repo, tmp_checksum, NULL, &ret_info, NULL,
                                   cancellable, error))
@@ -885,10 +890,15 @@ ostree_repo_file_tree_query_child (OstreeRepoFile  *self,
 
       if (n < c)
         {
+          const guchar *csum_bytes;
+
           g_variant_get_child (dirs_variant, n, "(&s ay@ay)",
                                &name, NULL, &meta_csum_v);
-          ostree_checksum_inplace_from_bytes (ostree_checksum_bytes_peek (meta_csum_v),
-                                              tmp_checksum);
+          csum_bytes = ostree_checksum_bytes_peek_validate (meta_csum_v, error);
+          if (csum_bytes == NULL)
+            goto out;
+
+          ostree_checksum_inplace_from_bytes (csum_bytes, tmp_checksum);
 
           if (!query_child_info_dir (self->repo, tmp_checksum,
                                      matcher, flags, &ret_info,
diff --git a/src/libostree/ostree-repo-pull.c b/src/libostree/ostree-repo-pull.c
index 76cd027..57c3689 100644
--- a/src/libostree/ostree-repo-pull.c
+++ b/src/libostree/ostree-repo-pull.c
@@ -501,6 +501,8 @@ scan_dirtree_object (OtPullData   *pull_data,
     {
       g_autoptr(GVariant) tree_csum = NULL;
       g_autoptr(GVariant) meta_csum = NULL;
+      const guchar *tree_csum_bytes;
+      const guchar *meta_csum_bytes;
 
       g_variant_get_child (dirs_variant, i, "(&s ay@ay)",
                            &dirname, &tree_csum, &meta_csum);
@@ -511,9 +513,17 @@ scan_dirtree_object (OtPullData   *pull_data,
       if (subdir_target && strcmp (subdir_target, dirname) != 0)
         continue;
 
-      queue_scan_one_metadata_object_c (pull_data, ostree_checksum_bytes_peek (tree_csum),
+      tree_csum_bytes = ostree_checksum_bytes_peek_validate (tree_csum, error);
+      if (tree_csum_bytes == NULL)
+        goto out;
+
+      meta_csum_bytes = ostree_checksum_bytes_peek_validate (meta_csum, error);
+      if (meta_csum_bytes == NULL)
+        goto out;
+
+      queue_scan_one_metadata_object_c (pull_data, tree_csum_bytes,
                                         OSTREE_OBJECT_TYPE_DIR_TREE, recursion_depth + 1);
-      queue_scan_one_metadata_object_c (pull_data, ostree_checksum_bytes_peek (meta_csum),
+      queue_scan_one_metadata_object_c (pull_data, meta_csum_bytes,
                                         OSTREE_OBJECT_TYPE_DIR_META, recursion_depth + 1);
     }
 
@@ -1002,9 +1012,9 @@ scan_commit_object (OtPullData         *pull_data,
                     GError            **error)
 {
   gboolean ret = FALSE;
-  gboolean have_parent;
   g_autoptr(GVariant) commit = NULL;
   g_autoptr(GVariant) parent_csum = NULL;
+  const guchar *parent_csum_bytes = NULL;
   gpointer depthp;
   gint depth;
 
@@ -1061,19 +1071,25 @@ scan_commit_object (OtPullData         *pull_data,
 
   /* PARSE OSTREE_SERIALIZED_COMMIT_VARIANT */
   g_variant_get_child (commit, 1, "@ay", &parent_csum);
-  have_parent = g_variant_n_children (parent_csum) > 0;
-  if (have_parent && pull_data->maxdepth == -1)
+  if (g_variant_n_children (parent_csum) > 0)
     {
-      queue_scan_one_metadata_object_c (pull_data, ostree_checksum_bytes_peek (parent_csum),
+      parent_csum_bytes = ostree_checksum_bytes_peek_validate (parent_csum, error);
+      if (parent_csum_bytes == NULL)
+        goto out;
+    }
+
+  if (parent_csum_bytes != NULL && pull_data->maxdepth == -1)
+    {
+      queue_scan_one_metadata_object_c (pull_data, parent_csum_bytes,
                                         OSTREE_OBJECT_TYPE_COMMIT, recursion_depth + 1);
     }
-  else if (have_parent && depth > 0)
+  else if (parent_csum_bytes != NULL && depth > 0)
     {
       char parent_checksum[65];
       gpointer parent_depthp;
       int parent_depth;
 
-      ostree_checksum_inplace_from_bytes (ostree_checksum_bytes_peek (parent_csum), parent_checksum);
+      ostree_checksum_inplace_from_bytes (parent_csum_bytes, parent_checksum);
   
       if (g_hash_table_lookup_extended (pull_data->commit_to_depth, parent_checksum,
                                         NULL, &parent_depthp))
@@ -1089,7 +1105,7 @@ scan_commit_object (OtPullData         *pull_data,
         {
           g_hash_table_insert (pull_data->commit_to_depth, g_strdup (parent_checksum),
                                GINT_TO_POINTER (parent_depth));
-          queue_scan_one_metadata_object_c (pull_data, ostree_checksum_bytes_peek (parent_csum),
+          queue_scan_one_metadata_object_c (pull_data, parent_csum_bytes,
                                             OSTREE_OBJECT_TYPE_COMMIT, recursion_depth + 1);
         }
     }
@@ -1098,13 +1114,24 @@ scan_commit_object (OtPullData         *pull_data,
     {
       g_autoptr(GVariant) tree_contents_csum = NULL;
       g_autoptr(GVariant) tree_meta_csum = NULL;
+      const guchar *tree_contents_csum_bytes;
+      const guchar *tree_meta_csum_bytes;
 
       g_variant_get_child (commit, 6, "@ay", &tree_contents_csum);
       g_variant_get_child (commit, 7, "@ay", &tree_meta_csum);
 
-      queue_scan_one_metadata_object_c (pull_data, ostree_checksum_bytes_peek (tree_contents_csum),
+      tree_contents_csum_bytes = ostree_checksum_bytes_peek_validate (tree_contents_csum, error);
+      if (tree_contents_csum_bytes == NULL)
+        goto out;
+
+      tree_meta_csum_bytes = ostree_checksum_bytes_peek_validate (tree_meta_csum, error);
+      if (tree_meta_csum_bytes == NULL)
+        goto out;
+
+      queue_scan_one_metadata_object_c (pull_data, tree_contents_csum_bytes,
                                         OSTREE_OBJECT_TYPE_DIR_TREE, recursion_depth + 1);
-      queue_scan_one_metadata_object_c (pull_data, ostree_checksum_bytes_peek (tree_meta_csum),
+
+      queue_scan_one_metadata_object_c (pull_data, tree_meta_csum_bytes,
                                         OSTREE_OBJECT_TYPE_DIR_META, recursion_depth + 1);
     }
 
diff --git a/src/libostree/ostree-repo-refs.c b/src/libostree/ostree-repo-refs.c
index 23e47fc..6d3bd51 100644
--- a/src/libostree/ostree-repo-refs.c
+++ b/src/libostree/ostree-repo-refs.c
@@ -633,10 +633,15 @@ ostree_repo_remote_list_refs (OstreeRepo       *self,
 
           if (ref_name != NULL)
             {
+              const guchar *csum_bytes;
+
               g_variant_get_child (child, 1, "(t aya{sv})", NULL, &csum_v, NULL);
+              csum_bytes = ostree_checksum_bytes_peek_validate (csum_v, error);
+              if (csum_bytes == NULL)
+                goto out;
+
+              ostree_checksum_inplace_from_bytes (csum_bytes, tmp_checksum);
 
-              ostree_checksum_inplace_from_bytes (ostree_checksum_bytes_peek (csum_v),
-                                                  tmp_checksum);
               g_hash_table_insert (ret_all_refs,
                                    g_strdup (ref_name),
                                    g_strdup (tmp_checksum));