avcodec/utvideodec: fix assumtation that slice_height >= 1

Fixes out of array read
Fixes: asan_heap-oob_2573085_3783_utvideo_rgba_median.avi
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 7656c4c6e66f8a787d384f027ad824cc1677fda1)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

diff --git a/libavcodec/utvideodec.c b/libavcodec/utvideodec.c
index 1c76773..ff69a25 100644 (file)
--- a/libavcodec/utvideodec.c
+++ b/libavcodec/utvideodec.c
@@ -222,7 +222,7 @@ static void restore_median(uint8_t *src, int step, int stride,
             A        = bsrc[i];
         }
         bsrc += stride;
-        if (slice_height == 1)
+        if (slice_height <= 1)
             continue;
         // second line - first element has top prediction, the rest uses median
         C        = bsrc[-stride];
@@ -282,7 +282,7 @@ static void restore_median_il(uint8_t *src, int step, int stride,
             A                 = bsrc[stride + i];
         }
         bsrc += stride2;
-        if (slice_height == 1)
+        if (slice_height <= 1)
             continue;
         // second line - first element has top prediction, the rest uses median
         C        = bsrc[-stride2];