Commit a281f3ca73 for ffmpeg

commit a281f3ca736805f473c69710730d3d61c6314a14
Author: Michael Niedermayer <michael@niedermayer.cc>
Date:   Wed Nov 11 17:00:32 2026 +0100

    avformat/mov: do not copy an empty index to the IAMF substreams

    Fixes: null pointer passed as argument 2, which is declared to never be null
    Fixes: DPPYwrys5OTb

    Found during the triage of a finding from the review of https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25671

    Null pointer argument Replicated through UnModified FFmpeg with UBSAN

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 65f66f6c15..30be8d5b67 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5561,7 +5561,8 @@ static int mov_update_iamf_streams(MOVContext *c, const AVStream *st)
             out_sti->index_entries_allocated_size = sti->index_entries_allocated_size;
             out_sti->nb_index_entries = sti->nb_index_entries;
             out_sti->skip_samples = sti->skip_samples;
-            memcpy(out_sti->index_entries, sti->index_entries, sti->index_entries_allocated_size);
+            if (sti->index_entries_allocated_size)
+                memcpy(out_sti->index_entries, sti->index_entries, sti->index_entries_allocated_size);
         }
     }