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swscale: take first/lastline over/underflows into account for MMX. 

Fixes crashes for extremely large resizes (several 100-fold).

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit 1d8c4af396)

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Ronald S. Bultje 2012-02-22 16:48:38 -08:00 committed by Reinhard Tartler
parent cd9bdc6395
commit 0c60d5c59f
1 changed files with 38 additions and 0 deletions
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38
libswscale/x86/swscale_mmx.c
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@ -132,6 +132,44 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
const int16_t **chrUSrcPtr= (const int16_t **) chrUPixBuf + chrBufIndex + firstChrSrcY - lastInChrBuf + vChrBufSize;
const int16_t **alpSrcPtr= (CONFIG_SWSCALE_ALPHA && alpPixBuf) ? (const int16_t **) alpPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize : NULL;
int i;
if (firstLumSrcY < 0 || firstLumSrcY + vLumFilterSize > c->srcH) {
const int16_t **tmpY = (const int16_t **) lumPixBuf + 2 * vLumBufSize;
int neg = -firstLumSrcY, i, end = FFMIN(c->srcH - firstLumSrcY, vLumFilterSize);
for (i = 0; i < neg; i++)
tmpY[i] = lumSrcPtr[neg];
for ( ; i < end; i++)
tmpY[i] = lumSrcPtr[i];
for ( ; i < vLumFilterSize; i++)
tmpY[i] = tmpY[i-1];
lumSrcPtr = tmpY;
if (alpSrcPtr) {
const int16_t **tmpA = (const int16_t **) alpPixBuf + 2 * vLumBufSize;
for (i = 0; i < neg; i++)
tmpA[i] = alpSrcPtr[neg];
for ( ; i < end; i++)
tmpA[i] = alpSrcPtr[i];
for ( ; i < vLumFilterSize; i++)
tmpA[i] = tmpA[i - 1];
alpSrcPtr = tmpA;
}
}
if (firstChrSrcY < 0 || firstChrSrcY + vChrFilterSize > c->chrSrcH) {
const int16_t **tmpU = (const int16_t **) chrUPixBuf + 2 * vChrBufSize;
int neg = -firstChrSrcY, i, end = FFMIN(c->chrSrcH - firstChrSrcY, vChrFilterSize);
for (i = 0; i < neg; i++) {
tmpU[i] = chrUSrcPtr[neg];
}
for ( ; i < end; i++) {
tmpU[i] = chrUSrcPtr[i];
}
for ( ; i < vChrFilterSize; i++) {
tmpU[i] = tmpU[i - 1];
}
chrUSrcPtr = tmpU;
}
if (flags & SWS_ACCURATE_RND) {
int s= APCK_SIZE / 8;
for (i=0; i<vLumFilterSize; i+=2) {