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Clamp out-of-range alpha-scale radius in validate_config #679

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Merged
solidpixel merged 3 commits into from
Oct 21, 2026
Merged

Clamp out-of-range alpha-scale radius in validate_config #679

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5c05f65
Clamp out-of-range alpha-scale radius in validate_config
17krishna8 Oct 20, 2026
3c71694
Add unit test for an out-of-range alpha-scale radius
17krishna8 Oct 20, 2026
94c0f70
Cleanup comments and rename new config option as its not a tuning option
solidpixel Oct 21, 2026
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35 changes: 35 additions & 0 deletions Source/UnitTest/test_encode.cpp
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Expand Up @@ -96,6 +96,41 @@ TEST(compress, overflow_in_16)
astcenc_context_free(context);
}

/** @brief Input test for an out-of-range alpha-scale radius. */
TEST(compress, ascale_radius_clamped)
{
astcenc_error status;
astcenc_config config;
astcenc_context* context;

static const astcenc_swizzle swizzle {
ASTCENC_SWZ_R, ASTCENC_SWZ_G, ASTCENC_SWZ_B, ASTCENC_SWZ_A
};

astcenc_config_init(ASTCENC_PRF_LDR, 4, 4, 1, ASTCENC_PRE_MEDIUM, 0, &config);

// Set to largest possible value to check input validation
config.a_scale_radius = 0xFFFFFFFFu;
status = astcenc_context_alloc(&config, 1, &context, nullptr);
EXPECT_EQ(status, ASTCENC_SUCCESS);

uint8_t data[16];
uint8_t input[4 * 4 * 4];

astcenc_image image;
image.dim_x = 4;
image.dim_y = 4;
image.dim_z = 1;
image.data_type = ASTCENC_TYPE_U8;
uint8_t* slices = input;
image.data = reinterpret_cast<void**>(&slices);

// Compression should succeed without bad_alloc or ASAN failure
status = astcenc_compress_image(context, &image, &swizzle, data, sizeof(data), 0);
EXPECT_EQ(status, ASTCENC_SUCCESS);

astcenc_context_free(context);
}

/** @brief Input data buffer overrun tests. */
TEST(compress, data_buffer_exceeded)
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3 changes: 3 additions & 0 deletions Source/astcenc_entry.cpp
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Expand Up @@ -464,6 +464,9 @@ static astcenc_error validate_config(

config.rgbm_m_scale = astc::max(config.rgbm_m_scale, 1.0f);

// Clamp alpha-scale kernel radius to put an upper bound on memory use
config.a_scale_radius = astc::min(config.a_scale_radius, ALPHASCALE_MAX_RADIUS);

config.tune_partition_count_limit = astc::clamp(config.tune_partition_count_limit, 1u, 4u);
config.tune_2partition_index_limit = astc::clamp(config.tune_2partition_index_limit, 1u, BLOCK_MAX_PARTITIONINGS);
config.tune_3partition_index_limit = astc::clamp(config.tune_3partition_index_limit, 1u, BLOCK_MAX_PARTITIONINGS);
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3 changes: 3 additions & 0 deletions Source/astcenc_internal.h
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Expand Up @@ -120,6 +120,9 @@ static constexpr unsigned int WEIGHTS_MAX_DECIMATION_MODES { 87 };
/** @brief The high default error used to initialize error trackers. */
static constexpr float ERROR_CALC_DEFAULT { 1e30f };

/** @brief The maximum alpha-scale kernel radius. */
static constexpr unsigned int ALPHASCALE_MAX_RADIUS { 64 };

/**
* @brief The minimum tuning setting threshold for the one partition fast path.
*/
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