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Avoid undefined behavior in a division operation.

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BUG: webrtc:5486
Change-Id: I2850fbec3283b81b49ee4f966349a94aabc2bf82
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215969
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Minyue Li <minyue@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33811}
This commit is contained in:
Minyue Li 2021-04-23 00:58:24 +02:00 committed by Commit Bot
parent 6674b9879a
commit 5663ce9152
1 changed files with 3 additions and 4 deletions
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7
common_audio/signal_processing/division_operations.c
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@ -98,8 +98,7 @@ int32_t WebRtcSpl_DivResultInQ31(int32_t num, int32_t den)
return div;
}
int32_t RTC_NO_SANITIZE("signed-integer-overflow") // bugs.webrtc.org/5486
WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low)
int32_t WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low)
{
int16_t approx, tmp_hi, tmp_low, num_hi, num_low;
int32_t tmpW32;
@ -111,8 +110,8 @@ WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low)
tmpW32 = (den_hi * approx << 1) + ((den_low * approx >> 15) << 1);
// tmpW32 = den * approx
tmpW32 = (int32_t)0x7fffffffL - tmpW32; // result in Q30 (tmpW32 = 2.0-(den*approx))
// UBSan: 2147483647 - -2 cannot be represented in type 'int'
// result in Q30 (tmpW32 = 2.0-(den*approx))
tmpW32 = (int32_t)((int64_t)0x7fffffffL - tmpW32);
// Store tmpW32 in hi and low format
tmp_hi = (int16_t)(tmpW32 >> 16);