[FFmpeg-cvslog] swscale: enforce a minimum filtersize.

[Ronald S. Bultje]

ffmpeg | branch: release/0.8 | Ronald S. Bultje <rsbultje at gmail.com> | Sat Feb 11 08:42:28 2012 -0800| [ce99c1bfb5968ea680c6c48a52c407677db2fe82] | committer: Reinhard Tartler

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 at libav.org
(cherry picked from commit dae2ce361a2b5fd9be1d43e5e8c00bdbc5f03e3d)

Signed-off-by: Anton Khirnov <anton at khirnov.net>
Signed-off-by: Reinhard Tartler <siretart at tauware.de>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ce99c1bfb5968ea680c6c48a52c407677db2fe82
---

 libswscale/utils.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/libswscale/utils.c b/libswscale/utils.c
index ac22dfe..221b993 100644
--- a/libswscale/utils.c
+++ b/libswscale/utils.c
@@ -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);