avformat/asfdec_f: Check name_len for overflow

Fixes: signed integer overflow: -1172299744 * 2 cannot be represented in type 'int'
Fixes: 26258/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5672758488596480

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/asfdec_f.c

@@ -769,6 +769,8 @@ static int asf_read_marker(AVFormatContext *s, int64_t size)
         avio_rl32(pb);             // send time
         avio_rl32(pb);             // flags
         name_len = avio_rl32(pb);  // name length
+        if ((unsigned)name_len > INT_MAX / 2)
+            return AVERROR_INVALIDDATA;
         if ((ret = avio_get_str16le(pb, name_len * 2, name,
                                     sizeof(name))) < name_len)
             avio_skip(pb, name_len - ret);