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    Contents of /trunk/audiofile/patches/audiofile-0.3.6-Check-for-multiplication-overflow-in-MSADPCM-decodeSam.patch

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    Revision 3077 - (show annotations) (download)
    Mon Jan 22 12:38:50 2018 UTC (6 years, 3 months ago) by niro
    File size: 3707 byte(s) 
    -added several security and build fixes
    1 From: Antonio Larrosa <larrosa@kde.org>
    2 Date: Mon, 6 Mar 2017 13:43:53 +0100
    3 Subject: Check for multiplication overflow in MSADPCM decodeSample
    4
    5 Check for multiplication overflow (using __builtin_mul_overflow
    6 if available) in MSADPCM.cpp decodeSample and return an empty
    7 decoded block if an error occurs.
    8
    9 This fixes the 00193-audiofile-signintoverflow-MSADPCM case of #41
    10 ---
    11 libaudiofile/modules/BlockCodec.cpp | 5 ++--
    12 libaudiofile/modules/MSADPCM.cpp | 47 +++++++++++++++++++++++++++++++++----
    13 2 files changed, 46 insertions(+), 6 deletions(-)
    14
    15 diff --git a/libaudiofile/modules/BlockCodec.cpp b/libaudiofile/modules/BlockCodec.cpp
    16 index 45925e8..4731be1 100644
    17 --- a/libaudiofile/modules/BlockCodec.cpp
    18 +++ b/libaudiofile/modules/BlockCodec.cpp
    19 @@ -52,8 +52,9 @@ void BlockCodec::runPull()
    20 // Decompress into m_outChunk.
    21 for (int i=0; i<blocksRead; i++)
    22 {
    23 - decodeBlock(static_cast<const uint8_t *>(m_inChunk->buffer) + i * m_bytesPerPacket,
    24 - static_cast<int16_t *>(m_outChunk->buffer) + i * m_framesPerPacket * m_track->f.channelCount);
    25 + if (decodeBlock(static_cast<const uint8_t *>(m_inChunk->buffer) + i * m_bytesPerPacket,
    26 + static_cast<int16_t *>(m_outChunk->buffer) + i * m_framesPerPacket * m_track->f.channelCount)==0)
    27 + break;
    28
    29 framesRead += m_framesPerPacket;
    30 }
    31 diff --git a/libaudiofile/modules/MSADPCM.cpp b/libaudiofile/modules/MSADPCM.cpp
    32 index 8ea3c85..ef9c38c 100644
    33 --- a/libaudiofile/modules/MSADPCM.cpp
    34 +++ b/libaudiofile/modules/MSADPCM.cpp
    35 @@ -101,24 +101,60 @@ static const int16_t adaptationTable[] =
    36 768, 614, 512, 409, 307, 230, 230, 230
    37 };
    38
    39 +int firstBitSet(int x)
    40 +{
    41 + int position=0;
    42 + while (x!=0)
    43 + {
    44 + x>>=1;
    45 + ++position;
    46 + }
    47 + return position;
    48 +}
    49 +
    50 +#ifndef __has_builtin
    51 +#define __has_builtin(x) 0
    52 +#endif
    53 +
    54 +int multiplyCheckOverflow(int a, int b, int *result)
    55 +{
    56 +#if (defined __GNUC__ && __GNUC__ >= 5) || ( __clang__ && __has_builtin(__builtin_mul_overflow))
    57 + return __builtin_mul_overflow(a, b, result);
    58 +#else
    59 + if (firstBitSet(a)+firstBitSet(b)>31) // int is signed, so we can't use 32 bits
    60 + return true;
    61 + *result = a * b;
    62 + return false;
    63 +#endif
    64 +}
    65 +
    66 +
    67 // Compute a linear PCM value from the given differential coded value.
    68 static int16_t decodeSample(ms_adpcm_state &state,
    69 - uint8_t code, const int16_t *coefficient)
    70 + uint8_t code, const int16_t *coefficient, bool *ok=NULL)
    71 {
    72 int linearSample = (state.sample1 * coefficient[0] +
    73 state.sample2 * coefficient[1]) >> 8;
    74 + int delta;
    75
    76 linearSample += ((code & 0x08) ? (code - 0x10) : code) * state.delta;
    77
    78 linearSample = clamp(linearSample, MIN_INT16, MAX_INT16);
    79
    80 - int delta = (state.delta * adaptationTable[code]) >> 8;
    81 + if (multiplyCheckOverflow(state.delta, adaptationTable[code], &delta))
    82 + {
    83 + if (ok) *ok=false;
    84 + _af_error(AF_BAD_COMPRESSION, "Error decoding sample");
    85 + return 0;
    86 + }
    87 + delta >>= 8;
    88 if (delta < 16)
    89 delta = 16;
    90
    91 state.delta = delta;
    92 state.sample2 = state.sample1;
    93 state.sample1 = linearSample;
    94 + if (ok) *ok=true;
    95
    96 return static_cast<int16_t>(linearSample);
    97 }
    98 @@ -212,13 +248,16 @@ int MSADPCM::decodeBlock(const uint8_t *encoded, int16_t *decoded)
    99 {
    100 uint8_t code;
    101 int16_t newSample;
    102 + bool ok;
    103
    104 code = *encoded >> 4;
    105 - newSample = decodeSample(*state[0], code, coefficient[0]);
    106 + newSample = decodeSample(*state[0], code, coefficient[0], &ok);
    107 + if (!ok) return 0;
    108 *decoded++ = newSample;
    109
    110 code = *encoded & 0x0f;
    111 - newSample = decodeSample(*state[1], code, coefficient[1]);
    112 + newSample = decodeSample(*state[1], code, coefficient[1], &ok);
    113 + if (!ok) return 0;
    114 *decoded++ = newSample;
    115
    116 encoded++;