Commit 64afb8a930 for ffmpeg

commit 64afb8a930b3bf7a02013e0655085275862f4efc
Author: zhang xingxing <2388969553@qq.com>
Date:   Tue Oct 13 06:59:47 2026 +0200

    avcodec/cbs_apv: reject user defined metadata shorter than its UUID

    This is not a security issue.

    Fixes: 00smV7L5DOfY
    Fixes: swarm-metadata_user_defined-data_size-underflows-on-payload_size-16-5ff8a8

    Found-by: zhang xingxing <2388969553@qq.com>
    Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/cbs_apv_syntax_template.c b/libavcodec/cbs_apv_syntax_template.c
index 8640bcfa00..3cdb320ca4 100644
--- a/libavcodec/cbs_apv_syntax_template.c
+++ b/libavcodec/cbs_apv_syntax_template.c
@@ -441,6 +441,9 @@ static int FUNC(metadata_user_defined)(CodedBitstreamContext *ctx,

     HEADER("User-Defined Metadata");

+    if (payload_size < 16)
+        return AVERROR_INVALIDDATA;
+
     for (int i = 0; i < 16; i++)
         ubs(8, uuid[i], 1, i);