avcodec/truespeech: reject iterations count whose * 240 product overflows 32-bit

Found-by: Anthropic agents; validated and reported by Ada Logics.
Signed-off-by: David Korczynski <david@adalogics.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit d30dead35e)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 5251f49710950561a85e49b2b2f43500c04ccf22)

libavcodec/truespeech.c

@@ -323,6 +323,11 @@ static int truespeech_decode_frame(AVCodecContext *avctx, AVFrame *frame,
                "Too small input buffer (%d bytes), need at least 32 bytes\n", buf_size);
         return -1;
     }
+    if (iterations > INT_MAX / 240) {
+        av_log(avctx, AV_LOG_ERROR,
+               "Too large input buffer (%d bytes); per-block sample count overflows\n", buf_size);
+        return AVERROR_INVALIDDATA;
+    }
 
     /* get output buffer */
     frame->nb_samples = iterations * 240;