Handle out of memory/bad size situation gracefully, without getting into loop

Zend/zend_mm.c

@@ -318,9 +318,15 @@ zend_mm_finished_searching_for_block:
 	if (!best_fit) {
 		if (true_size > (heap->block_size - ZEND_MM_ALIGNED_SEGMENT_SIZE - ZEND_MM_ALIGNED_HEADER_SIZE)) {
 			/* Make sure we add a memory block which is big enough */
-			zend_mm_add_memory_block(heap, true_size + ZEND_MM_ALIGNED_SEGMENT_SIZE + ZEND_MM_ALIGNED_HEADER_SIZE);
+			if (zend_mm_add_memory_block(heap, true_size + ZEND_MM_ALIGNED_SEGMENT_SIZE + ZEND_MM_ALIGNED_HEADER_SIZE)) {
+				zend_error(E_ERROR, "Out of memory: cannot allocate %d bytes!", true_size);
+				return NULL;
+			}
 		} else {
-			zend_mm_add_memory_block(heap, heap->block_size);
+			if (zend_mm_add_memory_block(heap, heap->block_size)) {
+				zend_error(E_ERROR, "Out of memory: cannot allocate %d bytes!", heap->block_size);
+				return NULL;
+			}
 		}
 		return zend_mm_alloc(heap, size);
 	}