swscale: enforce a minimum filtersize.

At very small dimensions, this calculation could lead to zero-sized
filters, which leads to uninitialized output, zero-sized allocations,
loop overflows in SIMD that uses do{..}while(i++<filtersize); instead
of for(i=0;i<filtersize;i++){..} and several other similar failures.
Therefore, require a minimum filtersize of 1.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit dae2ce361a2b5fd9be1d43e5e8c00bdbc5f03e3d)

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Reinhard Tartler <siretart@tauware.de>
This commit is contained in:
Ronald S. Bultje 2012-02-11 08:42:28 -08:00 committed by Reinhard Tartler
parent fd3af2950a
commit ce99c1bfb5

View File

@ -289,7 +289,7 @@ static int initFilter(int16_t **outFilter, int16_t **filterPos, int *outFilterSi
if (xInc <= 1<<16) filterSize= 1 + sizeFactor; // upscale
else filterSize= 1 + (sizeFactor*srcW + dstW - 1)/ dstW;
if (filterSize > srcW-2) filterSize=srcW-2;
filterSize = av_clip(filterSize, 1, srcW - 2);
FF_ALLOC_OR_GOTO(NULL, filter, dstW*sizeof(*filter)*filterSize, fail);