Fix overflowing mults in NTRUHRSS701

crypto_kem/ntruhrss701/clean/sample.c

@@ -37,14 +37,14 @@ void PQCLEAN_NTRUHRSS701_CLEAN_sample_iid_plus(poly *r, const unsigned char unif
 
     /* s = <x*r, r>.  (r[n-1] = 0) */
     for (i = 0; i < NTRU_N - 1; i++) {
-        s += r->coeffs[i + 1] * r->coeffs[i];
+        s += (uint16_t)((uint32_t)r->coeffs[i + 1] * (uint32_t)r->coeffs[i]);
     }
 
     /* Extract sign of s (sign(0) = 1) */
     s = 1 | (-(s >> 15));
 
     for (i = 0; i < NTRU_N; i += 2) {
-        r->coeffs[i] = s * r->coeffs[i];
+        r->coeffs[i] = (uint16_t)((uint32_t)s * (uint32_t)r->coeffs[i]);
     }
 
     /* Map {0,1,2^16-1} -> {0, 1, 2} */