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astc: Return zero on out of bound bits

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Avoid out of bound reads on invalid ASTC textures.
Games can bind invalid textures that make us read or write out of bounds.
This commit is contained in:
ReinUsesLisp 2021-01-15 02:15:04 -03:00
parent 93f7719eed
commit 0ec71b78fb
1 changed files with 22 additions and 17 deletions
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39
src/video_core/textures/astc.cpp
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@ -42,21 +42,24 @@ constexpr u32 Popcnt(u32 n) {
class InputBitStream {
public:
constexpr explicit InputBitStream(const u8* ptr, std::size_t start_offset = 0)
: cur_byte{ptr}, next_bit{start_offset % 8} {}
constexpr explicit InputBitStream(std::span<const u8> data, size_t start_offset = 0)
: cur_byte{data.data()}, total_bits{data.size()}, next_bit{start_offset % 8} {}
constexpr std::size_t GetBitsRead() const {
constexpr size_t GetBitsRead() const {
return bits_read;
}
constexpr bool ReadBit() {
const bool bit = (*cur_byte >> next_bit++) & 1;
if (bits_read >= total_bits * 8) {
return 0;
}
const bool bit = ((*cur_byte >> next_bit) & 1) != 0;
++next_bit;
while (next_bit >= 8) {
next_bit -= 8;
cur_byte++;
++cur_byte;
}
bits_read++;
++bits_read;
return bit;
}
@ -79,8 +82,9 @@ public:
private:
const u8* cur_byte;
std::size_t next_bit = 0;
std::size_t bits_read = 0;
size_t total_bits = 0;
size_t next_bit = 0;
size_t bits_read = 0;
};
class OutputBitStream {
@ -200,8 +204,8 @@ using IntegerEncodedVector = boost::container::static_vector<
static void DecodeTritBlock(InputBitStream& bits, IntegerEncodedVector& result, u32 nBitsPerValue) {
// Implement the algorithm in section C.2.12
u32 m[5];
u32 t[5];
std::array<u32, 5> m;
std::array<u32, 5> t;
u32 T;
// Read the trit encoded block according to
@ -866,7 +870,7 @@ public:
}
};
static void DecodeColorValues(u32* out, u8* data, const u32* modes, const u32 nPartitions,
static void DecodeColorValues(u32* out, std::span<u8> data, const u32* modes, const u32 nPartitions,
const u32 nBitsForColorData) {
// First figure out how many color values we have
u32 nValues = 0;
@ -898,7 +902,7 @@ static void DecodeColorValues(u32* out, u8* data, const u32* modes, const u32 nP
// We now have enough to decode our integer sequence.
IntegerEncodedVector decodedColorValues;
InputBitStream colorStream(data);
InputBitStream colorStream(data, 0);
DecodeIntegerSequence(decodedColorValues, colorStream, range, nValues);
// Once we have the decoded values, we need to dequantize them to the 0-255 range
@ -1441,7 +1445,7 @@ static void ComputeEndpos32s(Pixel& ep1, Pixel& ep2, const u32*& colorValues,
static void DecompressBlock(std::span<const u8, 16> inBuf, const u32 blockWidth,
const u32 blockHeight, std::span<u32, 12 * 12> outBuf) {
InputBitStream strm(inBuf.data());
InputBitStream strm(inBuf);
TexelWeightParams weightParams = DecodeBlockInfo(strm);
// Was there an error?
@ -1619,15 +1623,16 @@ static void DecompressBlock(std::span<const u8, 16> inBuf, const u32 blockWidth,
// Make sure that higher non-texel bits are set to zero
const u32 clearByteStart = (weightParams.GetPackedBitSize() >> 3) + 1;
if (clearByteStart > 0) {
if (clearByteStart > 0 && clearByteStart <= texelWeightData.size()) {
texelWeightData[clearByteStart - 1] &=
static_cast<u8>((1 << (weightParams.GetPackedBitSize() % 8)) - 1);
std::memset(texelWeightData.data() + clearByteStart, 0,
std::min(16U - clearByteStart, 16U));
}
std::memset(texelWeightData.data() + clearByteStart, 0, std::min(16U - clearByteStart, 16U));
IntegerEncodedVector texelWeightValues;
InputBitStream weightStream(texelWeightData.data());
InputBitStream weightStream(texelWeightData);
DecodeIntegerSequence(texelWeightValues, weightStream, weightParams.m_MaxWeight,
weightParams.GetNumWeightValues());