From beacc44eb8cdf6d58717ec1a5103c5141f1b37f9 Mon Sep 17 00:00:00 2001 From: Antonio Larrosa Date: Mon, 6 Mar 2017 13:43:53 +0100 Subject: [PATCH 2/3] Check for multiplication overflow in MSADPCM decodeSample Check for multiplication overflow (using __builtin_mul_overflow if available) in MSADPCM.cpp decodeSample and return an empty decoded block if an error occurs. This fixes the 00193-audiofile-signintoverflow-MSADPCM case of #41 --- libaudiofile/modules/BlockCodec.cpp | 5 +-- libaudiofile/modules/MSADPCM.cpp | 47 ++++++++++++++++++++++++++--- 2 files changed, 46 insertions(+), 6 deletions(-) diff --git a/libaudiofile/modules/BlockCodec.cpp b/libaudiofile/modules/BlockCodec.cpp index 45925e8..4731be1 100644 --- a/libaudiofile/modules/BlockCodec.cpp +++ b/libaudiofile/modules/BlockCodec.cpp @@ -52,8 +52,9 @@ void BlockCodec::runPull() // Decompress into m_outChunk. for (int i=0; i(m_inChunk->buffer) + i * m_bytesPerPacket, - static_cast(m_outChunk->buffer) + i * m_framesPerPacket * m_track->f.channelCount); + if (decodeBlock(static_cast(m_inChunk->buffer) + i * m_bytesPerPacket, + static_cast(m_outChunk->buffer) + i * m_framesPerPacket * m_track->f.channelCount)==0) + break; framesRead += m_framesPerPacket; } diff --git a/libaudiofile/modules/MSADPCM.cpp b/libaudiofile/modules/MSADPCM.cpp index 8ea3c85..ef9c38c 100644 --- a/libaudiofile/modules/MSADPCM.cpp +++ b/libaudiofile/modules/MSADPCM.cpp @@ -101,24 +101,60 @@ static const int16_t adaptationTable[] = 768, 614, 512, 409, 307, 230, 230, 230 }; +int firstBitSet(int x) +{ + int position=0; + while (x!=0) + { + x>>=1; + ++position; + } + return position; +} + +#ifndef __has_builtin +#define __has_builtin(x) 0 +#endif + +int multiplyCheckOverflow(int a, int b, int *result) +{ +#if (defined __GNUC__ && __GNUC__ >= 5) || ( __clang__ && __has_builtin(__builtin_mul_overflow)) + return __builtin_mul_overflow(a, b, result); +#else + if (firstBitSet(a)+firstBitSet(b)>31) // int is signed, so we can't use 32 bits + return true; + *result = a * b; + return false; +#endif +} + + // Compute a linear PCM value from the given differential coded value. static int16_t decodeSample(ms_adpcm_state &state, - uint8_t code, const int16_t *coefficient) + uint8_t code, const int16_t *coefficient, bool *ok=NULL) { int linearSample = (state.sample1 * coefficient[0] + state.sample2 * coefficient[1]) >> 8; + int delta; linearSample += ((code & 0x08) ? (code - 0x10) : code) * state.delta; linearSample = clamp(linearSample, MIN_INT16, MAX_INT16); - int delta = (state.delta * adaptationTable[code]) >> 8; + if (multiplyCheckOverflow(state.delta, adaptationTable[code], &delta)) + { + if (ok) *ok=false; + _af_error(AF_BAD_COMPRESSION, "Error decoding sample"); + return 0; + } + delta >>= 8; if (delta < 16) delta = 16; state.delta = delta; state.sample2 = state.sample1; state.sample1 = linearSample; + if (ok) *ok=true; return static_cast(linearSample); } @@ -212,13 +248,16 @@ int MSADPCM::decodeBlock(const uint8_t *encoded, int16_t *decoded) { uint8_t code; int16_t newSample; + bool ok; code = *encoded >> 4; - newSample = decodeSample(*state[0], code, coefficient[0]); + newSample = decodeSample(*state[0], code, coefficient[0], &ok); + if (!ok) return 0; *decoded++ = newSample; code = *encoded & 0x0f; - newSample = decodeSample(*state[1], code, coefficient[1]); + newSample = decodeSample(*state[1], code, coefficient[1], &ok); + if (!ok) return 0; *decoded++ = newSample; encoded++; -- 2.36.1