From: Antonio Larrosa <larrosa@kde.org> Date: Mon, 6 Mar 2017 13:54:52 +0100 Subject: Check for multiplication overflow in sfconvert 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 #41 --- sfcommands/sfconvert.c | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/sfcommands/sfconvert.c b/sfcommands/sfconvert.c index 80a1bc4..970a3e4 100644 --- a/sfcommands/sfconvert.c +++ b/sfcommands/sfconvert.c @@ -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) @@ -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;