[FFmpeg-devel] [PR] avcodec/mjpegdec: fix segfault on extern_huff and no extradata (PR #21519)

[Ramiro Polla via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #21519 opened by Ramiro Polla (ramiro)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21519
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21519.patch

Regression since 1debadd58e.


>From 7fbae1e8ad1cb46610f5a3f17bcb4830684026d5 Mon Sep 17 00:00:00 2001
From: Ramiro Polla <ramiro.polla@gmail.com>
Date: Mon, 19 Jan 2026 18:04:12 +0100
Subject: [PATCH] avcodec/mjpegdec: fix segfault on extern_huff and no
 extradata

Regression since 1debadd58e.
---
 libavcodec/mjpegdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 3af4b05551..c110130393 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -145,7 +145,7 @@ av_cold int ff_mjpeg_decode_init(AVCodecContext *avctx)
     if ((ret = init_default_huffman_tables(s)) < 0)
         return ret;
 
-    if (s->extern_huff) {
+    if (s->extern_huff && avctx->extradata) {
         av_log(avctx, AV_LOG_INFO, "using external huffman table\n");
         bytestream2_init(&s->gB, avctx->extradata, avctx->extradata_size);
         if (ff_mjpeg_decode_dht(s)) {
-- 
2.52.0

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