Fix integer overflow in insertPitchPeriod/enlargeOutputBufferIfNeeded - #4
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austek wants to merge 1 commit into
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Fix integer overflow in insertPitchPeriod/enlargeOutputBufferIfNeeded#4austek wants to merge 1 commit into
austek wants to merge 1 commit into
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period + newSamples is computed correctly in long in insertPitchPeriod, but was truncated to int when passed into enlargeOutputBufferIfNeeded's int parameter. Inside that function, the int addition numOutputSamples + numSamples and the buffer growth calculation can also signed-overflow, both leading to a too-small allocation followed by writes sized for the original, larger sample count. Guard both: insertPitchPeriod now checks the long sum against INT_MAX before truncating, and enlargeOutputBufferIfNeeded checks its own addition for overflow before applying it, returning 0 through the existing failure path in both cases instead of invoking undefined behavior. Adds tests/overflow_test.c, a white-box test that calls both functions directly (they are no longer static, for this reason) with values chosen to hit the overflow guards. Ported from waywardgeek/sonic#62, which fixes the same bug (also present here, byte-identical insertPitchPeriod/enlargeOutputBufferIfNeeded) upstream.
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Summary
period + newSamplesis computed correctly inlongininsertPitchPeriod, but was truncated tointwhen passed intoenlargeOutputBufferIfNeeded'sintparameter. Inside that function, theintadditionnumOutputSamples + numSamplesand the buffer growth calculation can also signed-overflow, leading to a too-small allocation followed by writes sized for the original, larger sample count.Guards both:
insertPitchPeriodnow checks thelongsum againstINT_MAXbefore truncating, andenlargeOutputBufferIfNeededchecks its own addition for overflow before applying it, returning 0 through the existing failure path in both cases instead of invoking undefined behavior.Same bug, same fix as waywardgeek/sonic#62 — this repo's
insertPitchPeriod/enlargeOutputBufferIfNeededare byte-identical to what that file had upstream, so the fix ports directly.Test plan
cd tests && make runtests && ./runtests— passes, newtests/overflow_test.cincluded-fsanitize=address,undefined— no finding from this path; only the separate, already-knownfindSincCoefficientleft-shift issue remains