Commit 78f288d5 authored by Andy Polyakov's avatar Andy Polyakov
Browse files

bn_mont.c: get corner cases right in updated BN_from_montgomery_word.

parent 8329e2e7

crypto/bn/bn_mont.c

+6 −6
Original line number Diff line number Diff line
@@ -196,9 +196,9 @@ static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) 
	/* clear the top words of T */

#if 1

	for (i=r->top; i<max; i++) /* memset? XXX */

		r->d[i]=0;

		rp[i]=0;

#else

	memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 

	memset(&(rp[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 

#endif



	r->top=max;
@@ -225,10 +225,10 @@ static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) 
#else

		v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);

#endif

		if ((rp[nl] = (rp[nl]+v+carry)&BN_MASK2) < v)

			carry = 1;

		else

			carry = 0;

		v = (v+carry+rp[nl])&BN_MASK2;

		carry |= (v != rp[nl]);

		carry &= (v <= rp[nl]);

		rp[nl]=v;

		}



	if (bn_wexpand(ret,nl) == NULL) return(0);