From d3576d034e111cc830c455b9244aa812981387b6 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Wed, 7 Oct 2026 00:06:08 +0200
Subject: [PATCH] avformat/rdt: Allocate the RMStream of a stream only once

A repeated ASMRuleBook line allocated a new RMStream for every stream it
had already set up, leaking the old one.

Memory leak Replicated through UnModified FFmpeg with ASAN
Found during triage of the security report PXsIMPp0wPaW
---
 libavformat/rdt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavformat/rdt.c b/libavformat/rdt.c
index 725793eb01..7bab6ce522 100644
--- a/libavformat/rdt.c
+++ b/libavformat/rdt.c
@@ -440,6 +440,8 @@ rdt_parse_sdp_line (AVFormatContext *s, int st_index,
                            (count - rdt->nb_rmst) * sizeof(*rdt->rmst));
                     rdt->nb_rmst = count;
                 }
+                if (rdt->rmst[s->streams[n]->index])
+                    continue;
                 rdt->rmst[s->streams[n]->index] = ff_rm_alloc_rmstream();
                 if (!rdt->rmst[s->streams[n]->index])
                     return AVERROR(ENOMEM);