avcodec/jpeg2000dec: Check atom_size in jp2_find_codestream()

Fixes: Infinite loop
Fixes: 29722/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-6412228041506816

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

libavcodec/jpeg2000dec.c

@@ -2342,8 +2342,12 @@ static int jp2_find_codestream(Jpeg2000DecoderContext *s)
                 return 0;
             }
             atom_size = bytestream2_get_be32u(&s->g);
+            if (atom_size < 16 || (int64_t)bytestream2_tell(&s->g) + atom_size - 16 > INT_MAX)
+                return AVERROR_INVALIDDATA;
             atom_end  = bytestream2_tell(&s->g) + atom_size - 16;
         } else {
+            if (atom_size <  8 || (int64_t)bytestream2_tell(&s->g) + atom_size -  8 > INT_MAX)
+                return AVERROR_INVALIDDATA;
             atom_end  = bytestream2_tell(&s->g) + atom_size -  8;
         }