Commit a43bcd9e authored by Emilia Kasper's avatar Emilia Kasper
Browse files

Check for invalid divisors in BN_div. 



Invalid zero-padding in the divisor could cause a division by 0.

Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
parent c8667a2e

crypto/bn/bn_div.c

+5 −3
Original line number Diff line number Diff line
@@ -189,15 +189,17 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, 
	int no_branch=0;



	/* Invalid zero-padding would have particularly bad consequences

	 * in the case of 'num', so don't just rely on bn_check_top() for this one

	 * so don't just rely on bn_check_top() here

	 * (bn_check_top() works only for BN_DEBUG builds) */

	if (num->top > 0 && num->d[num->top - 1] == 0)

	if ((num->top > 0 && num->d[num->top - 1] == 0) ||

		(divisor->top > 0 && divisor->d[divisor->top - 1] == 0))

		{

		BNerr(BN_F_BN_DIV,BN_R_NOT_INITIALIZED);

		return 0;

		}



	bn_check_top(num);

	bn_check_top(divisor);



	if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0))

		{
@@ -207,7 +209,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, 
	bn_check_top(dv);

	bn_check_top(rm);

	/* bn_check_top(num); */ /* 'num' has been checked already */

	bn_check_top(divisor);

	/* bn_check_top(divisor); */ /* 'divisor' has been checked already */



	if (BN_is_zero(divisor))

		{