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- From beacc44eb8cdf6d58717ec1a5103c5141f1b37f9 Mon Sep 17 00:00:00 2001
- From: Antonio Larrosa <larrosa@kde.org>
- Date: Mon, 6 Mar 2017 13:43:53 +0100
- Subject: [PATCH] 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<blocksRead; i++)
- {
- - decodeBlock(static_cast<const uint8_t *>(m_inChunk->buffer) + i * m_bytesPerPacket,
- - static_cast<int16_t *>(m_outChunk->buffer) + i * m_framesPerPacket * m_track->f.channelCount);
- + if (decodeBlock(static_cast<const uint8_t *>(m_inChunk->buffer) + i * m_bytesPerPacket,
- + static_cast<int16_t *>(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<int16_t>(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++;
- --
- 2.11.0
-
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