avcodec/jpeg2000dec: Check PPx / PPy values

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/jpeg2000dec.c

@@ -461,6 +461,13 @@ static int get_cox(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c)
             byte = bytestream2_get_byte(&s->g);
             c->log2_prec_widths[i]  =  byte       & 0x0F;    // precinct PPx
             c->log2_prec_heights[i] = (byte >> 4) & 0x0F;    // precinct PPy
+            if (i)
+                if (c->log2_prec_widths[i] == 0 || c->log2_prec_heights[i] == 0) {
+                    av_log(s->avctx, AV_LOG_ERROR, "PPx %d PPy %d invalid\n",
+                           c->log2_prec_widths[i], c->log2_prec_heights[i]);
+                    c->log2_prec_widths[i] = c->log2_prec_heights[i] = 1;
+                    return AVERROR_INVALIDDATA;
+                }
         }
     } else {
         memset(c->log2_prec_widths , 15, sizeof(c->log2_prec_widths ));