libFLAC: More comment validation

When the allocation for obj->comment fails, set obj->num_comments
to zero.

Patch-from: lvqcl <lvqcl.mail@gmail.com>

src/libFLAC/metadata_iterators.c

@@ -2255,8 +2255,10 @@ FLAC__Metadata_SimpleIteratorStatus read_metadata_block_data_vorbis_comment_cb_(
 	if(block->num_comments == 0) {
 		block->comments = 0;
 	}
-	else if(0 == (block->comments = calloc(block->num_comments, sizeof(FLAC__StreamMetadata_VorbisComment_Entry))))
+	else if(0 == (block->comments = calloc(block->num_comments, sizeof(FLAC__StreamMetadata_VorbisComment_Entry)))) {
+		block->num_comments = 0;
 		return FLAC__METADATA_SIMPLE_ITERATOR_STATUS_MEMORY_ALLOCATION_ERROR;
+	}
 
 	for(i = 0; i < block->num_comments; i++) {
 		status = read_metadata_block_data_vorbis_comment_entry_cb_(handle, read_cb, block->comments + i, block_length);

src/libFLAC/metadata_object.c

@@ -574,6 +574,7 @@ FLAC_API FLAC__StreamMetadata *FLAC__metadata_object_clone(const FLAC__StreamMet
 					FLAC__ASSERT(0 != object->data.vorbis_comment.comments);
 					to->data.vorbis_comment.comments = vorbiscomment_entry_array_copy_(object->data.vorbis_comment.comments, object->data.vorbis_comment.num_comments);
 					if(0 == to->data.vorbis_comment.comments) {
+						to->data.vorbis_comment.num_comments = 0;
 						FLAC__metadata_object_delete(to);
 						return 0;
 					}
@@ -1195,8 +1196,10 @@ FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_resize_comments(FLAC__St
 			free(object->data.vorbis_comment.comments);
 			object->data.vorbis_comment.comments = 0;
 		}
-		else if(0 == (object->data.vorbis_comment.comments = realloc(object->data.vorbis_comment.comments, new_size)))
+		else if(0 == (object->data.vorbis_comment.comments = realloc(object->data.vorbis_comment.comments, new_size))) {
+			object->data.vorbis_comment.num_comments = 0;
 			return false;
+		}
 
 		/* if growing, zero all the length/pointers of new elements */
 		if(new_size > old_size)

src/libFLAC/stream_decoder.c

@@ -1735,6 +1735,7 @@ FLAC__bool read_metadata_vorbiscomment_(FLAC__StreamDecoder *decoder, FLAC__Stre
 		}
 		if (obj->num_comments > 0) {
 			if (0 == (obj->comments = safe_malloc_mul_2op_p(obj->num_comments, /*times*/sizeof(FLAC__StreamMetadata_VorbisComment_Entry)))) {
+				obj->num_comments = 0;
 				decoder->protected_->state = FLAC__STREAM_DECODER_MEMORY_ALLOCATION_ERROR;
 				return false;
 			}