types: fix uninitialized memory on setting non-contiguous array indexes

When ucode sets array indexes far after the array end so that a realloc()
is triggered interally, the memory between the last existing array
element and the newly set one was left uninitialized, leading to
random segmentation faults, infinite loops or other invalid memory access
symptoms.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 5 insertions, 0 deletions

diff --git a/types.c b/types.c
index af56320..b1172eb 100644
--- a/types.c
+++ b/types.c
@@ -699,13 +699,18 @@ bool
 ucv_array_set(uc_value_t *uv, size_t index, uc_value_t *item)
 {
 	uc_array_t *array = (uc_array_t *)uv;
+	size_t old_count;
 
 	if (ucv_type(uv) != UC_ARRAY)
 		return false;
 
 	if (index >= array->count) {
+		old_count = array->count;
 		array->count = index + 1;
 		uc_vector_grow(array);
+
+		while (old_count < array->count)
+			array->entries[old_count++] = NULL;
 	}
 	else {
 		ucv_put(array->entries[index]);