rmdec: Validate the fps value

Abort if it is invalid if strict error checking has been requested.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/rmdec.c

@@ -332,8 +332,13 @@ ff_rm_read_mdpr_codecdata (AVFormatContext *s, AVIOContext *pb,
         if ((ret = rm_read_extradata(pb, st->codec, codec_data_size - (avio_tell(pb) - codec_pos))) < 0)
             return ret;
 
-        av_reduce(&st->avg_frame_rate.den, &st->avg_frame_rate.num,
-                  0x10000, fps, (1 << 30) - 1);
+        if (fps > 0) {
+            av_reduce(&st->avg_frame_rate.den, &st->avg_frame_rate.num,
+                      0x10000, fps, (1 << 30) - 1);
+        } else if (s->error_recognition & AV_EF_EXPLODE) {
+            av_log(s, AV_LOG_ERROR, "Invalid framerate\n");
+            return AVERROR_INVALIDDATA;
+        }
     }
 
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