Merge pull request #5348 from ReinUsesLisp/astc-robustness
astc: Make the decoder more robust to invalid data
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commit
6dc1d48fd1
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@ -42,21 +42,24 @@ constexpr u32 Popcnt(u32 n) {
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class InputBitStream {
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public:
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constexpr explicit InputBitStream(const u8* ptr, std::size_t start_offset = 0)
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: cur_byte{ptr}, next_bit{start_offset % 8} {}
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constexpr explicit InputBitStream(std::span<const u8> data, size_t start_offset = 0)
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: cur_byte{data.data()}, total_bits{data.size()}, next_bit{start_offset % 8} {}
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constexpr std::size_t GetBitsRead() const {
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constexpr size_t GetBitsRead() const {
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return bits_read;
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}
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constexpr bool ReadBit() {
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const bool bit = (*cur_byte >> next_bit++) & 1;
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if (bits_read >= total_bits * 8) {
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return 0;
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}
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const bool bit = ((*cur_byte >> next_bit) & 1) != 0;
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++next_bit;
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while (next_bit >= 8) {
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next_bit -= 8;
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cur_byte++;
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++cur_byte;
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}
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bits_read++;
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++bits_read;
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return bit;
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}
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@ -79,8 +82,9 @@ public:
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private:
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const u8* cur_byte;
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std::size_t next_bit = 0;
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std::size_t bits_read = 0;
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size_t total_bits = 0;
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size_t next_bit = 0;
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size_t bits_read = 0;
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};
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class OutputBitStream {
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@ -193,15 +197,15 @@ struct IntegerEncodedValue {
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};
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};
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using IntegerEncodedVector = boost::container::static_vector<
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IntegerEncodedValue, 64,
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IntegerEncodedValue, 256,
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boost::container::static_vector_options<
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boost::container::inplace_alignment<alignof(IntegerEncodedValue)>,
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boost::container::throw_on_overflow<false>>::type>;
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static void DecodeTritBlock(InputBitStream& bits, IntegerEncodedVector& result, u32 nBitsPerValue) {
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// Implement the algorithm in section C.2.12
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u32 m[5];
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u32 t[5];
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std::array<u32, 5> m;
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std::array<u32, 5> t;
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u32 T;
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// Read the trit encoded block according to
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@ -866,7 +870,7 @@ public:
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}
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};
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static void DecodeColorValues(u32* out, u8* data, const u32* modes, const u32 nPartitions,
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static void DecodeColorValues(u32* out, std::span<u8> data, const u32* modes, const u32 nPartitions,
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const u32 nBitsForColorData) {
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// First figure out how many color values we have
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u32 nValues = 0;
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@ -898,7 +902,7 @@ static void DecodeColorValues(u32* out, u8* data, const u32* modes, const u32 nP
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// We now have enough to decode our integer sequence.
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IntegerEncodedVector decodedColorValues;
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InputBitStream colorStream(data);
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InputBitStream colorStream(data, 0);
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DecodeIntegerSequence(decodedColorValues, colorStream, range, nValues);
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// Once we have the decoded values, we need to dequantize them to the 0-255 range
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@ -1441,7 +1445,7 @@ static void ComputeEndpos32s(Pixel& ep1, Pixel& ep2, const u32*& colorValues,
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static void DecompressBlock(std::span<const u8, 16> inBuf, const u32 blockWidth,
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const u32 blockHeight, std::span<u32, 12 * 12> outBuf) {
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InputBitStream strm(inBuf.data());
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InputBitStream strm(inBuf);
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TexelWeightParams weightParams = DecodeBlockInfo(strm);
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// Was there an error?
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@ -1619,15 +1623,16 @@ static void DecompressBlock(std::span<const u8, 16> inBuf, const u32 blockWidth,
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// Make sure that higher non-texel bits are set to zero
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const u32 clearByteStart = (weightParams.GetPackedBitSize() >> 3) + 1;
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if (clearByteStart > 0) {
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if (clearByteStart > 0 && clearByteStart <= texelWeightData.size()) {
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texelWeightData[clearByteStart - 1] &=
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static_cast<u8>((1 << (weightParams.GetPackedBitSize() % 8)) - 1);
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std::memset(texelWeightData.data() + clearByteStart, 0,
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std::min(16U - clearByteStart, 16U));
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}
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std::memset(texelWeightData.data() + clearByteStart, 0, std::min(16U - clearByteStart, 16U));
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IntegerEncodedVector texelWeightValues;
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InputBitStream weightStream(texelWeightData.data());
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InputBitStream weightStream(texelWeightData);
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DecodeIntegerSequence(texelWeightValues, weightStream, weightParams.m_MaxWeight,
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weightParams.GetNumWeightValues());
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