From ce99c1bfb5968ea680c6c48a52c407677db2fe82 Mon Sep 17 00:00:00 2001
From: "Ronald S. Bultje" <rsbultje@gmail.com>
Date: Sat, 11 Feb 2012 08:42:28 -0800
Subject: [PATCH] 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>
---
 libswscale/utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libswscale/utils.c b/libswscale/utils.c
index ac22dfe688..221b993305 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);