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VadCore: Allow signed multiplication overflow that we don't know how to fix

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The right thing to do would be to ensure that the multiplication can't
overflow, but that'd be a major change bordering on a rewrite, and
would take too much time. So instead, we just instruct UBSan to look
the other way.

BUG=chromium:634834

Review-Url: https://codereview.webrtc.org/2318083002
Cr-Commit-Position: refs/heads/master@{#14154}
This commit is contained in:
kwiberg 2016-09-09 02:04:38 -07:00 committed by Commit bot
parent 3fa35172cd
commit 27c7b8ff11
2 changed files with 20 additions and 1 deletions
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9
webrtc/base/sanitizer.h
View File

@ -33,6 +33,15 @@
#include <sanitizer/msan_interface.h>
#endif
#ifdef __has_attribute
#if __has_attribute(no_sanitize)
#define RTC_NO_SANITIZE(what) __attribute__((no_sanitize(what)))
#endif
#endif
#ifndef RTC_NO_SANITIZE
#define RTC_NO_SANITIZE(what)
#endif
// Ask ASan to mark the memory range [ptr, ptr + element_size * num_elements)
// as being unaddressable, so that reads and writes are not allowed. ASan may
// narrow the range to the nearest alignment boundaries.

12
webrtc/common_audio/vad/vad_core.c
View File

@ -10,6 +10,7 @@
#include "webrtc/common_audio/vad/vad_core.h"
#include "webrtc/base/sanitizer.h"
#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
#include "webrtc/common_audio/vad/vad_filterbank.h"
#include "webrtc/common_audio/vad/vad_gmm.h"
@ -110,6 +111,15 @@ static int32_t WeightedAverage(int16_t* data, int16_t offset,
return weighted_average;
}
// An s16 x s32 -> s32 multiplication that's allowed to overflow. (It's still
// undefined behavior, so not a good idea; this just makes UBSan ignore the
// violation, so that our old code can continue to do what it's always been
// doing.)
static inline int32_t OverflowingMulS16ByS32ToS32(int16_t a, int32_t b)
RTC_NO_SANITIZE("signed-integer-overflow") {
return a * b;
}
// Calculates the probabilities for both speech and background noise using
// Gaussian Mixture Models (GMM). A hypothesis-test is performed to decide which
// type of signal is most probable.
@ -378,7 +388,7 @@ static int16_t GmmProbability(VadInstT* self, int16_t* features,
// (Q14 >> 2) * Q12 = Q24.
tmp_s16 = (ngprvec[gaussian] + 2) >> 2;
tmp2_s32 = tmp_s16 * tmp1_s32;
tmp2_s32 = OverflowingMulS16ByS32ToS32(tmp_s16, tmp1_s32);
// Q20 * approx 0.001 (2^-10=0.0009766), hence,
// (Q24 >> 14) = (Q24 >> 4) / 2^10 = Q20.
tmp1_s32 = tmp2_s32 >> 14;