Merge branch 'mk/maint-parse-careful'

* mk/maint-parse-careful:
  peel_onion: handle NULL
  check return value from parse_commit() in various functions
  parse_commit: don't fail, if object is NULL
  revision.c: handle tag->tagged == NULL
  reachable.c::process_tree/blob: check for NULL
  process_tag: handle tag->tagged == NULL
  check results of parse_commit in merge_bases
  list-objects.c::process_tree/blob: check for NULL
  reachable.c::add_one_tree: handle NULL from lookup_tree
  mark_blob/tree_uninteresting: check for NULL
  get_sha1_oneline: check return value of parse_object
  read_object_with_reference: don't read beyond the buffer

commit.c

@@ -311,6 +311,8 @@ int parse_commit(struct commit *item)
 	unsigned long size;
 	int ret;
 
+	if (!item)
+		return -1;
 	if (item->object.parsed)
 		return 0;
 	buffer = read_sha1_file(item->object.sha1, &type, &size);
@@ -385,8 +387,7 @@ struct commit *pop_most_recent_commit(struct commit_list **list,
 
 	while (parents) {
 		struct commit *commit = parents->item;
-		parse_commit(commit);
-		if (!(commit->object.flags & mark)) {
+		if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 			commit->object.flags |= mark;
 			insert_by_date(commit, list);
 		}
@@ -552,8 +553,10 @@ static struct commit_list *merge_bases(struct commit *one, struct commit *two)
 		 */
 		return commit_list_insert(one, &result);
 
-	parse_commit(one);
-	parse_commit(two);
+	if (parse_commit(one))
+		return NULL;
+	if (parse_commit(two))
+		return NULL;
 
 	one->object.flags |= PARENT1;
 	two->object.flags |= PARENT2;
@@ -586,7 +589,8 @@ static struct commit_list *merge_bases(struct commit *one, struct commit *two)
 			parents = parents->next;
 			if ((p->object.flags & flags) == flags)
 				continue;
-			parse_commit(p);
+			if (parse_commit(p))
+				return NULL;
 			p->object.flags |= flags;
 			insert_by_date(p, &list);
 		}

list-objects.c

@@ -18,6 +18,8 @@ static void process_blob(struct rev_info *revs,
 
 	if (!revs->blob_objects)
 		return;
+	if (!obj)
+		die("bad blob object");
 	if (obj->flags & (UNINTERESTING | SEEN))
 		return;
 	obj->flags |= SEEN;
@@ -69,6 +71,8 @@ static void process_tree(struct rev_info *revs,
 
 	if (!revs->tree_objects)
 		return;
+	if (!obj)
+		die("bad tree object");
 	if (obj->flags & (UNINTERESTING | SEEN))
 		return;
 	if (parse_tree(tree) < 0)

reachable.c

@@ -15,6 +15,8 @@ static void process_blob(struct blob *blob,
 {
 	struct object *obj = &blob->object;
 
+	if (!blob)
+		die("bad blob object");
 	if (obj->flags & SEEN)
 		return;
 	obj->flags |= SEEN;
@@ -39,6 +41,8 @@ static void process_tree(struct tree *tree,
 	struct name_entry entry;
 	struct name_path me;
 
+	if (!tree)
+		die("bad tree object");
 	if (obj->flags & SEEN)
 		return;
 	obj->flags |= SEEN;
@@ -79,7 +83,8 @@ static void process_tag(struct tag *tag, struct object_array *p, const char *nam
 
 	if (parse_tag(tag) < 0)
 		die("bad tag object %s", sha1_to_hex(obj->sha1));
-	add_object(tag->tagged, p, NULL, name);
+	if (tag->tagged)
+		add_object(tag->tagged, p, NULL, name);
 }
 
 static void walk_commit_list(struct rev_info *revs)
@@ -150,7 +155,8 @@ static int add_one_reflog(const char *path, const unsigned char *sha1, int flag,
 static void add_one_tree(const unsigned char *sha1, struct rev_info *revs)
 {
 	struct tree *tree = lookup_tree(sha1);
-	add_pending_object(revs, &tree->object, "");
+	if (tree)
+		add_pending_object(revs, &tree->object, "");
 }
 
 static void add_cache_tree(struct cache_tree *it, struct rev_info *revs)

revision.c

@@ -46,6 +46,8 @@ void add_object(struct object *obj,
 
 static void mark_blob_uninteresting(struct blob *blob)
 {
+	if (!blob)
+		return;
 	if (blob->object.flags & UNINTERESTING)
 		return;
 	blob->object.flags |= UNINTERESTING;
@@ -57,6 +59,8 @@ void mark_tree_uninteresting(struct tree *tree)
 	struct name_entry entry;
 	struct object *obj = &tree->object;
 
+	if (!tree)
+		return;
 	if (obj->flags & UNINTERESTING)
 		return;
 	obj->flags |= UNINTERESTING;
@@ -173,6 +177,8 @@ static struct commit *handle_commit(struct rev_info *revs, struct object *object
 		struct tag *tag = (struct tag *) object;
 		if (revs->tag_objects && !(flags & UNINTERESTING))
 			add_pending_object(revs, object, tag->tag);
+		if (!tag->tagged)
+			die("bad tag");
 		object = parse_object(tag->tagged->sha1);
 		if (!object)
 			die("bad object %s", sha1_to_hex(tag->tagged->sha1));
@@ -685,6 +691,8 @@ static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 		it = get_reference(revs, arg, sha1, 0);
 		if (it->type != OBJ_TAG)
 			break;
+		if (!((struct tag*)it)->tagged)
+			return 0;
 		hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 	}
 	if (it->type != OBJ_COMMIT)

sha1_file.c

@@ -1943,7 +1943,8 @@ void *read_object_with_reference(const unsigned char *sha1,
 		}
 		ref_length = strlen(ref_type);
 
-		if (memcmp(buffer, ref_type, ref_length) ||
+		if (ref_length + 40 > isize ||
+		    memcmp(buffer, ref_type, ref_length) ||
 		    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
 			free(buffer);
 			return NULL;

sha1_name.c

@@ -494,8 +494,11 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 				return error("%.*s: expected %s type, but the object dereferences to %s type",
 					     len, name, typename(expected_type),
 					     typename(o->type));
+			if (!o)
+				return -1;
 			if (!o->parsed)
-				parse_object(o->sha1);
+				if (!parse_object(o->sha1))
+					return -1;
 		}
 	}
 	return 0;
@@ -620,7 +623,8 @@ static int get_sha1_oneline(const char *prefix, unsigned char *sha1)
 		unsigned long size;
 
 		commit = pop_most_recent_commit(&list, ONELINE_SEEN);
-		parse_object(commit->object.sha1);
+		if (!parse_object(commit->object.sha1))
+			continue;
 		if (temp_commit_buffer)
 			free(temp_commit_buffer);
 		if (commit->buffer)

shallow.c

@@ -70,7 +70,8 @@ struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
 				cur_depth = *(int *)commit->util;
 			}
 		}
-		parse_commit(commit);
+		if (parse_commit(commit))
+			die("invalid commit");
 		commit->object.flags |= not_shallow_flag;
 		cur_depth++;
 		for (p = commit->parents, commit = NULL; p; p = p->next) {

upload-pack.c

@@ -534,7 +534,8 @@ static void receive_needs(void)
 				/* make sure the real parents are parsed */
 				unregister_shallow(object->sha1);
 				object->parsed = 0;
-				parse_commit((struct commit *)object);
+				if (parse_commit((struct commit *)object))
+					die("invalid commit");
 				parents = ((struct commit *)object)->parents;
 				while (parents) {
 					add_object_array(&parents->item->object,