ffmpeg-4/ffmpeg-CVE-2018-13305.patch

From d08d4a8c7387e758d439b0592782e4cfa2b4d6a4 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Thu, 28 Jun 2018 23:46:32 +0200
Subject: [PATCH] avcodec/vc1_block: Fix mqaunt check for negative values
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Fixes: out of array access
Fixes: ffmpeg_bof_4.avi
Fixes: ffmpeg_bof_5.avi
Fixes: ffmpeg_bof_6.avi

Found-by: Thuan Pham, Marcel Böhme, Andrew Santosa and Alexandru Razvan Caciulescu with AFLSmart
Reviewed-by: Jerome Borsboom <jerome.borsboom@carpalis.nl>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/vc1_block.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: ffmpeg-4.0.2/libavcodec/vc1_block.c
===================================================================
--- ffmpeg-4.0.2.orig/libavcodec/vc1_block.c
+++ ffmpeg-4.0.2/libavcodec/vc1_block.c
@@ -188,7 +188,7 @@ static void vc1_put_signed_blocks_clampe
             mquant = v->altpq;                                 \
         if ((edges&8) && s->mb_y == (s->mb_height - 1))        \
             mquant = v->altpq;                                 \
-        if (!mquant || mquant > 31) {                          \
+        if (!mquant || mquant > 31 || mquant < -31) { \
             av_log(v->s.avctx, AV_LOG_ERROR,                   \
                    "Overriding invalid mquant %d\n", mquant);  \
             mquant = 1;                                        \