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stagefright aacenc: Avoid overflows when calculating normFactor

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normFactor is calculated using the saturating L_add function,
but if the value added (*psfbPeFactors) is negative, the sum
can end up negative.

*psfbPeFactors can end up negative if redThrExp is less than
*psfbNActiveLines.

In cases where *psfbPeFactors ended up negative, normFactor
became INT_MIN, causing division by zero later.

Change-Id: I00c852e457b22f7eef4d6ed1887629828057206b
This commit is contained in:
Martin Storsjo
2012-02-19 21:46:24 +02:00
parent 23d3628628
commit 27bd8da964
1 changed files with 1 additions and 1 deletions
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2
media/libstagefright/codecs/aacenc/src/adj_thr.c
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@@ -437,7 +437,7 @@ static void correctThresh(PSY_OUT_CHANNEL psyOutChannel[MAX_CHANNELS],
for (sfb=0; sfb<psyOutChan->maxSfbPerGroup; sfb++) {
Word32 redThrExp = thrExp[ch][sfbGrp+sfb] + redVal;
if (((*pahFlag < AH_ACTIVE) || (deltaPe > 0)) && (redThrExp > 0) ) {
if (((*pahFlag < AH_ACTIVE) || (deltaPe > 0)) && (redThrExp > 0) && (redThrExp >= *psfbNActiveLines)) {
*psfbPeFactors = (*psfbNActiveLines) * (0x7fffffff / redThrExp);
normFactor = L_add(normFactor, *psfbPeFactors);