avcodec/diracdec: Check slice numbers for overflows in relation to picture dimensions

Fixes: signed integer overflow: 88 * 33685506 cannot be represented in type 'int'
Fixes: 9433/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DIRAC_fuzzer-5725943535501312

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

libavcodec/diracdec.c

@@ -1243,7 +1243,10 @@ static int dirac_unpack_idwt_params(DiracContext *s)
     else {
         s->num_x        = get_interleaved_ue_golomb(gb);
         s->num_y        = get_interleaved_ue_golomb(gb);
-        if (s->num_x * s->num_y == 0 || s->num_x * (uint64_t)s->num_y > INT_MAX) {
+        if (s->num_x * s->num_y == 0 || s->num_x * (uint64_t)s->num_y > INT_MAX ||
+            s->num_x * (uint64_t)s->avctx->width  > INT_MAX ||
+            s->num_y * (uint64_t)s->avctx->height > INT_MAX
+        ) {
             av_log(s->avctx,AV_LOG_ERROR,"Invalid numx/y\n");
             s->num_x = s->num_y = 0;
             return AVERROR_INVALIDDATA;