[FFmpeg-devel] [PATCH 3/3] avutil/opt: Preserve nb_channels in opt_free

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH 3/3] avutil/opt: Preserve nb_channels in opt_free
Date: Tue, 30 Apr 2024 02:48:54 +0200
Message-ID: <20240430004854.199741-3-michael@niedermayer.cc> (raw)
In-Reply-To: <20240430004854.199741-1-michael@niedermayer.cc>

Fixes: division by 0
Fixes: decoder modifying demuxer channels on failure
Fixes: -sseof -5 -i zgclab/ffmpeg_crash/poc3

Found-by: Wang Dawei and Zhou Geng, from Zhongguancun Laboratory
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavutil/opt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavutil/opt.c b/libavutil/opt.c
index ecbf7efe5fb..24c08e4bc06 100644
--- a/libavutil/opt.c
+++ b/libavutil/opt.c
@@ -132,9 +132,11 @@ static void opt_free_elem(const AVOption *o, void *ptr)
         av_dict_free((AVDictionary **)ptr);
         break;
 
-    case AV_OPT_TYPE_CHLAYOUT:
+    case AV_OPT_TYPE_CHLAYOUT: {
+        int nb_channels = ((AVChannelLayout *)ptr)->nb_channels;
         av_channel_layout_uninit((AVChannelLayout *)ptr);
-        break;
+        ((AVChannelLayout *)ptr)->nb_channels = nb_channels;
+        break;}
 
     default:
         break;
-- 
2.43.2

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