#ifdef PB_ENABLE_MALLOC
/* Allocate storage for the field and store the pointer at iter->pData.
- * array_size is the number of entries to reserve in an array. */
+ * array_size is the number of entries to reserve in an array.
+ * Zero size is not allowed, use pb_free() for releasing.
+ */
static bool checkreturn allocate_field(pb_istream_t *stream, void *pData, size_t data_size, size_t array_size)
{
void *ptr = *(void**)pData;
- size_t size = array_size * data_size;
+
+ /* Check for multiplication overflows.
+ * This code avoids the costly division if the sizes are small enough.
+ * Multiplication is safe as long as only half of bits are set
+ * in either multiplicand.
+ */
+ const size_t check_limit = (size_t)1 << (sizeof(size_t) * 4);
+ if (data_size >= check_limit || array_size >= check_limit)
+ {
+ const size_t size_max = (size_t)-1;
+ if (size_max / array_size < data_size)
+ {
+ PB_RETURN_ERROR(stream, "size too large");
+ }
+ }
/* Allocate new or expand previous allocation */
/* Note: on failure the old pointer will remain in the structure,
* the message must be freed by caller also on error return. */
- ptr = pb_realloc(ptr, size);
+ ptr = pb_realloc(ptr, array_size * data_size);
if (ptr == NULL)
PB_RETURN_ERROR(stream, "realloc failed");