Zero-init partition candidate stack arrays (#619)
The find_best_partition_candidates() function can use uninitialized data in the uncor_best_partitions and samec_best_partitions arrays as an index if most partition candidates fail to give a good result. Specifically, if fewer than requested_candidates result in an error that is lower than ERROR_CALC_DEFAULT, the tail of the array will not be initialized.
This is expected to be very unlikely in real use, where the data is a real texture and a large number of possible partition candidates are used, but it's possible if using a very restricted partition set with random texture data.
diff --git a/Source/astcenc_find_best_partitioning.cpp b/Source/astcenc_find_best_partitioning.cpp
index 2025889..8989a56 100644
--- a/Source/astcenc_find_best_partitioning.cpp
+++ b/Source/astcenc_find_best_partitioning.cpp
@@ -1,6 +1,6 @@
// SPDX-License-Identifier: Apache-2.0
// ----------------------------------------------------------------------------
-// Copyright 2011-2025 Arm Limited
+// Copyright 2011-2026 Arm Limited
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
@@ -587,11 +587,11 @@
// Partitioning errors assuming uncorrelated-chrominance endpoints
float uncor_best_errors[TUNE_MAX_PARTITIONING_CANDIDATES];
- unsigned int uncor_best_partitions[TUNE_MAX_PARTITIONING_CANDIDATES];
+ unsigned int uncor_best_partitions[TUNE_MAX_PARTITIONING_CANDIDATES] = {};
// Partitioning errors assuming same-chrominance endpoints
float samec_best_errors[TUNE_MAX_PARTITIONING_CANDIDATES];
- unsigned int samec_best_partitions[TUNE_MAX_PARTITIONING_CANDIDATES];
+ unsigned int samec_best_partitions[TUNE_MAX_PARTITIONING_CANDIDATES] = {};
for (unsigned int i = 0; i < requested_candidates; i++)
{
