avcodec/jpeg2000dec: Check image offset

Fixes: left shift of negative value -538967841
Fixes: 62447/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-6427134337613824

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Tomas Härdin <git@haerdin.se>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 88453250db)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/jpeg2000dec.c

@@ -323,6 +323,11 @@ static int get_siz(Jpeg2000DecoderContext *s)
         return AVERROR_INVALIDDATA;
     }
 
+    if (s->image_offset_x >= s->width || s->image_offset_y >= s->height) {
+        av_log(s->avctx, AV_LOG_ERROR, "image offsets outside image");
+        return AVERROR_INVALIDDATA;
+    }
+
     if (s->reduction_factor && (s->image_offset_x || s->image_offset_y) ){
         av_log(s->avctx, AV_LOG_ERROR, "reduction factor with image offsets is not fully implemented");
         return AVERROR_PATCHWELCOME;