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Check for multiplication overflow in sfconvert
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Checks that a multiplication doesn't overflow when
calculating the buffer size, and if it overflows,
reduce the buffer size instead of failing.

This fixes the 00192-audiofile-signintoverflow-sfconvert case
in mpruett#41
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antlarr committed Mar 6, 2017
1 parent beacc44 commit 7d65f89
Showing 1 changed file with 32 additions and 2 deletions.
34 changes: 32 additions & 2 deletions sfcommands/sfconvert.c
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,33 @@ void printusage (void);
void usageerror (void);
bool copyaudiodata (AFfilehandle infile, AFfilehandle outfile, int trackid);

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
}

int main (int argc, char **argv)
{
if (argc == 2)
Expand Down Expand Up @@ -323,8 +350,11 @@ bool copyaudiodata (AFfilehandle infile, AFfilehandle outfile, int trackid)
{
int frameSize = afGetVirtualFrameSize(infile, trackid, 1);

const int kBufferFrameCount = 65536;
void *buffer = malloc(kBufferFrameCount * frameSize);
int kBufferFrameCount = 65536;
int bufferSize;
while (multiplyCheckOverflow(kBufferFrameCount, frameSize, &bufferSize))
kBufferFrameCount /= 2;
void *buffer = malloc(bufferSize);

AFframecount totalFrames = afGetFrameCount(infile, AF_DEFAULT_TRACK);
AFframecount totalFramesWritten = 0;
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