Adjust various bignum functions to use BN_CTX for variables instead of

locally initialising their own.

NB: I've removed the "BN_clear_free()" loops for the exit-paths in some of
these functions, and that may be a major part of the performance
improvements we're seeing. The "free" part can be removed because we're
using BN_CTX. The "clear" part OTOH can be removed because BN_CTX
destruction automatically performs this task, so performing it inside
functions that may be called repeatedly is wasteful. This is currently safe
within openssl due to the fact that BN_CTX objects are never created for
longer than a single high-level operation. However, that is only because
there's currently no mechanism in openssl for thread-local storage. Beyond
that, this might be an issue for applications using the bignum API directly
and caching their own BN_CTX objects. The solution is to introduce a flag
to BN_CTX_start() that allows its variables to be automatically sanitised
on release during BN_CTX_end(). This way any higher-level function (and
perhaps the application) can specify this flag in its own
BN_CTX_start()/BN_CTX_end() pair, and this will cause inner-loop functions
specifying the flag to be ignored so that sanitisation is handled only once
back out at the higher level. I will be implementing this in the near
future.

crypto/bn/bn_exp.c

@@ -231,9 +231,10 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 		    const BIGNUM *m, BN_CTX *ctx)
 	{
 	int i,j,bits,ret=0,wstart,wend,window,wvalue;
-	int start=1,ts=0;
+	int start=1;
 	BIGNUM *aa;
-	BIGNUM val[TABLE_SIZE];
+	/* Table of variables obtained from 'ctx' */
+	BIGNUM *val[TABLE_SIZE];
 	BN_RECP_CTX recp;
 
 	bits=BN_num_bits(p);
@@ -245,7 +246,9 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 		}
 
 	BN_CTX_start(ctx);
-	if ((aa = BN_CTX_get(ctx)) == NULL) goto err;
+	aa = BN_CTX_get(ctx);
+	val[0] = BN_CTX_get(ctx);
+	if(!aa || !val[0]) goto err;
 
 	BN_RECP_CTX_init(&recp);
 	if (m->neg)
@@ -260,11 +263,8 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 		if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err;
 		}
 
-	BN_init(&(val[0]));
-	ts=1;
-
-	if (!BN_nnmod(&(val[0]),a,m,ctx)) goto err;		/* 1 */
-	if (BN_is_zero(&(val[0])))
+	if (!BN_nnmod(val[0],a,m,ctx)) goto err;		/* 1 */
+	if (BN_is_zero(val[0]))
 		{
 		BN_zero(r);
 		ret = 1;
@@ -274,16 +274,16 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 	window = BN_window_bits_for_exponent_size(bits);
 	if (window > 1)
 		{
-		if (!BN_mod_mul_reciprocal(aa,&(val[0]),&(val[0]),&recp,ctx))
+		if (!BN_mod_mul_reciprocal(aa,val[0],val[0],&recp,ctx))
 			goto err;				/* 2 */
 		j=1<<(window-1);
 		for (i=1; i<j; i++)
 			{
-			BN_init(&val[i]);
-			if (!BN_mod_mul_reciprocal(&(val[i]),&(val[i-1]),aa,&recp,ctx))
+			if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
+					!BN_mod_mul_reciprocal(val[i],val[i-1],
+						aa,&recp,ctx))
 				goto err;
 			}
-		ts=i;
 		}
 		
 	start=1;	/* This is used to avoid multiplication etc
@@ -335,7 +335,7 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 				}
 		
 		/* wvalue will be an odd number < 2^window */
-		if (!BN_mod_mul_reciprocal(r,r,&(val[wvalue>>1]),&recp,ctx))
+		if (!BN_mod_mul_reciprocal(r,r,val[wvalue>>1],&recp,ctx))
 			goto err;
 
 		/* move the 'window' down further */
@@ -347,8 +347,6 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 	ret=1;
 err:
 	BN_CTX_end(ctx);
-	for (i=0; i<ts; i++)
-		BN_clear_free(&(val[i]));
 	BN_RECP_CTX_free(&recp);
 	bn_check_top(r);
 	return(ret);
@@ -359,11 +357,11 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		    const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
 	{
 	int i,j,bits,ret=0,wstart,wend,window,wvalue;
-	int start=1,ts=0;
+	int start=1;
 	BIGNUM *d,*r;
 	const BIGNUM *aa;
-	/* TODO: BN_CTX??? */
-	BIGNUM val[TABLE_SIZE];
+	/* Table of variables obtained from 'ctx' */
+	BIGNUM *val[TABLE_SIZE];
 	BN_MONT_CTX *mont=NULL;
 
 	bn_check_top(a);
@@ -385,7 +383,8 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 	BN_CTX_start(ctx);
 	d = BN_CTX_get(ctx);
 	r = BN_CTX_get(ctx);
-	if (d == NULL || r == NULL) goto err;
+	val[0] = BN_CTX_get(ctx);
+	if (!d || !r || !val[0]) goto err;
 
 	/* If this is not done, things will break in the montgomery
 	 * part */
@@ -398,13 +397,11 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
 		}
 
-	BN_init(&val[0]);
-	ts=1;
 	if (a->neg || BN_ucmp(a,m) >= 0)
 		{
-		if (!BN_nnmod(&(val[0]),a,m,ctx))
+		if (!BN_nnmod(val[0],a,m,ctx))
 			goto err;
-		aa= &(val[0]);
+		aa= val[0];
 		}
 	else
 		aa=a;
@@ -414,20 +411,20 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		ret = 1;
 		goto err;
 		}
-	if (!BN_to_montgomery(&(val[0]),aa,mont,ctx)) goto err; /* 1 */
+	if (!BN_to_montgomery(val[0],aa,mont,ctx)) goto err; /* 1 */
 
 	window = BN_window_bits_for_exponent_size(bits);
 	if (window > 1)
 		{
-		if (!BN_mod_mul_montgomery(d,&(val[0]),&(val[0]),mont,ctx)) goto err; /* 2 */
+		if (!BN_mod_mul_montgomery(d,val[0],val[0],mont,ctx)) goto err; /* 2 */
 		j=1<<(window-1);
 		for (i=1; i<j; i++)
 			{
-			BN_init(&(val[i]));
-			if (!BN_mod_mul_montgomery(&(val[i]),&(val[i-1]),d,mont,ctx))
+			if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
+					!BN_mod_mul_montgomery(val[i],val[i-1],
+						d,mont,ctx))
 				goto err;
 			}
-		ts=i;
 		}
 
 	start=1;	/* This is used to avoid multiplication etc
@@ -480,7 +477,7 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 				}
 		
 		/* wvalue will be an odd number < 2^window */
-		if (!BN_mod_mul_montgomery(r,r,&(val[wvalue>>1]),mont,ctx))
+		if (!BN_mod_mul_montgomery(r,r,val[wvalue>>1],mont,ctx))
 			goto err;
 
 		/* move the 'window' down further */
@@ -494,8 +491,6 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 err:
 	if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
 	BN_CTX_end(ctx);
-	for (i=0; i<ts; i++)
-		BN_clear_free(&(val[i]));
 	bn_check_top(rr);
 	return(ret);
 	}
@@ -647,11 +642,11 @@ err:
 int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 		const BIGNUM *m, BN_CTX *ctx)
 	{
-	int i,j,bits,ret=0,wstart,wend,window,wvalue,ts=0;
+	int i,j,bits,ret=0,wstart,wend,window,wvalue;
 	int start=1;
 	BIGNUM *d;
-	/* TODO: BN_CTX?? */
-	BIGNUM val[TABLE_SIZE];
+	/* Table of variables obtained from 'ctx' */
+	BIGNUM *val[TABLE_SIZE];
 
 	bits=BN_num_bits(p);
 
@@ -662,12 +657,12 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 		}
 
 	BN_CTX_start(ctx);
-	if ((d = BN_CTX_get(ctx)) == NULL) goto err;
+	d = BN_CTX_get(ctx);
+	val[0] = BN_CTX_get(ctx);
+	if(!d || !val[0]) goto err;
 
-	BN_init(&(val[0]));
-	ts=1;
-	if (!BN_nnmod(&(val[0]),a,m,ctx)) goto err;		/* 1 */
-	if (BN_is_zero(&(val[0])))
+	if (!BN_nnmod(val[0],a,m,ctx)) goto err;		/* 1 */
+	if (BN_is_zero(val[0]))
 		{
 		BN_zero(r);
 		ret = 1;
@@ -677,16 +672,15 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 	window = BN_window_bits_for_exponent_size(bits);
 	if (window > 1)
 		{
-		if (!BN_mod_mul(d,&(val[0]),&(val[0]),m,ctx))
+		if (!BN_mod_mul(d,val[0],val[0],m,ctx))
 			goto err;				/* 2 */
 		j=1<<(window-1);
 		for (i=1; i<j; i++)
 			{
-			BN_init(&(val[i]));
-			if (!BN_mod_mul(&(val[i]),&(val[i-1]),d,m,ctx))
+			if(((val[i] = BN_CTX_get(ctx)) == NULL) ||
+					!BN_mod_mul(val[i],val[i-1],d,m,ctx))
 				goto err;
 			}
-		ts=i;
 		}
 
 	start=1;	/* This is used to avoid multiplication etc
@@ -738,7 +732,7 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 				}
 		
 		/* wvalue will be an odd number < 2^window */
-		if (!BN_mod_mul(r,r,&(val[wvalue>>1]),m,ctx))
+		if (!BN_mod_mul(r,r,val[wvalue>>1],m,ctx))
 			goto err;
 
 		/* move the 'window' down further */
@@ -750,8 +744,6 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 	ret=1;
 err:
 	BN_CTX_end(ctx);
-	for (i=0; i<ts; i++)
-		BN_clear_free(&(val[i]));
 	bn_check_top(r);
 	return(ret);
 	}

crypto/bn/bn_exp2.c

@@ -120,11 +120,11 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 	BN_CTX *ctx, BN_MONT_CTX *in_mont)
 	{
 	int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
-	int r_is_one=1,ts1=0,ts2=0;
+	int r_is_one=1;
 	BIGNUM *d,*r;
 	const BIGNUM *a_mod_m;
-	/* TODO: BN_CTX??? */
-	BIGNUM val1[TABLE_SIZE], val2[TABLE_SIZE];
+	/* Tables of variables obtained from 'ctx' */
+	BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
 	BN_MONT_CTX *mont=NULL;
 
 	bn_check_top(a1);
@@ -151,7 +151,9 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 	BN_CTX_start(ctx);
 	d = BN_CTX_get(ctx);
 	r = BN_CTX_get(ctx);
-	if (d == NULL || r == NULL) goto err;
+	val1[0] = BN_CTX_get(ctx);
+	val2[0] = BN_CTX_get(ctx);
+	if(!d || !r || !val1[0] || !val2[0]) goto err;
 
 	if (in_mont != NULL)
 		mont=in_mont;
@@ -167,13 +169,11 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 	/*
 	 * Build table for a1:   val1[i] := a1^(2*i + 1) mod m  for i = 0 .. 2^(window1-1)
 	 */
-	BN_init(&val1[0]);
-	ts1=1;
 	if (a1->neg || BN_ucmp(a1,m) >= 0)
 		{
-		if (!BN_mod(&(val1[0]),a1,m,ctx))
+		if (!BN_mod(val1[0],a1,m,ctx))
 			goto err;
-		a_mod_m = &(val1[0]);
+		a_mod_m = val1[0];
 		}
 	else
 		a_mod_m = a1;
@@ -184,32 +184,30 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 		goto err;
 		}
 
-	if (!BN_to_montgomery(&(val1[0]),a_mod_m,mont,ctx)) goto err;
+	if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err;
 	if (window1 > 1)
 		{
-		if (!BN_mod_mul_montgomery(d,&(val1[0]),&(val1[0]),mont,ctx)) goto err;
+		if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err;
 
 		j=1<<(window1-1);
 		for (i=1; i<j; i++)
 			{
-			BN_init(&(val1[i]));
-			if (!BN_mod_mul_montgomery(&(val1[i]),&(val1[i-1]),d,mont,ctx))
+			if(((val1[i] = BN_CTX_get(ctx)) == NULL) ||
+					!BN_mod_mul_montgomery(val1[i],val1[i-1],
+						d,mont,ctx))
 				goto err;
 			}
-		ts1=i;
 		}
 
 
 	/*
 	 * Build table for a2:   val2[i] := a2^(2*i + 1) mod m  for i = 0 .. 2^(window2-1)
 	 */
-	BN_init(&val2[0]);
-	ts2=1;
 	if (a2->neg || BN_ucmp(a2,m) >= 0)
 		{
-		if (!BN_mod(&(val2[0]),a2,m,ctx))
+		if (!BN_mod(val2[0],a2,m,ctx))
 			goto err;
-		a_mod_m = &(val2[0]);
+		a_mod_m = val2[0];
 		}
 	else
 		a_mod_m = a2;
@@ -219,19 +217,19 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 		ret = 1;
 		goto err;
 		}
-	if (!BN_to_montgomery(&(val2[0]),a_mod_m,mont,ctx)) goto err;
+	if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err;
 	if (window2 > 1)
 		{
-		if (!BN_mod_mul_montgomery(d,&(val2[0]),&(val2[0]),mont,ctx)) goto err;
+		if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err;
 
 		j=1<<(window2-1);
 		for (i=1; i<j; i++)
 			{
-			BN_init(&(val2[i]));
-			if (!BN_mod_mul_montgomery(&(val2[i]),&(val2[i-1]),d,mont,ctx))
+			if(((val2[i] = BN_CTX_get(ctx)) == NULL) ||
+					!BN_mod_mul_montgomery(val2[i],val2[i-1],
+						d,mont,ctx))
 				goto err;
 			}
-		ts2=i;
 		}
 
 
@@ -288,7 +286,7 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 		if (wvalue1 && b == wpos1)
 			{
 			/* wvalue1 is odd and < 2^window1 */
-			if (!BN_mod_mul_montgomery(r,r,&(val1[wvalue1>>1]),mont,ctx))
+			if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx))
 				goto err;
 			wvalue1 = 0;
 			r_is_one = 0;
@@ -297,7 +295,7 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 		if (wvalue2 && b == wpos2)
 			{
 			/* wvalue2 is odd and < 2^window2 */
-			if (!BN_mod_mul_montgomery(r,r,&(val2[wvalue2>>1]),mont,ctx))
+			if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx))
 				goto err;
 			wvalue2 = 0;
 			r_is_one = 0;
@@ -308,10 +306,6 @@ int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 err:
 	if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
 	BN_CTX_end(ctx);
-	for (i=0; i<ts1; i++)
-		BN_clear_free(&(val1[i]));
-	for (i=0; i<ts2; i++)
-		BN_clear_free(&(val2[i]));
 	bn_check_top(rr);
 	return(ret);
 	}

crypto/bn/bn_mont.c

@@ -271,9 +271,11 @@ void BN_MONT_CTX_free(BN_MONT_CTX *mont)
 
 int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
 	{
-	BIGNUM Ri,*R;
+	int ret = 0;
+	BIGNUM *Ri,*R;
 
-	BN_init(&Ri);
+	BN_CTX_start(ctx);
+	if((Ri = BN_CTX_get(ctx)) == NULL) goto err;
 	R= &(mont->RR);					/* grab RR as a temp */
 	BN_copy(&(mont->N),mod);			/* Set N */
 	mont->N.neg = 0;
@@ -294,22 +296,21 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
 		tmod.dmax=2;
 		tmod.neg=0;
 							/* Ri = R^-1 mod N*/
-		if ((BN_mod_inverse(&Ri,R,&tmod,ctx)) == NULL)
+		if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
 			goto err;
-		if (!BN_lshift(&Ri,&Ri,BN_BITS2)) goto err; /* R*Ri */
-		if (!BN_is_zero(&Ri))
+		if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */
+		if (!BN_is_zero(Ri))
 			{
-			if (!BN_sub_word(&Ri,1)) goto err;
+			if (!BN_sub_word(Ri,1)) goto err;
 			}
 		else /* if N mod word size == 1 */
 			{
-			if (!BN_set_word(&Ri,BN_MASK2)) goto err;  /* Ri-- (mod word size) */
+			if (!BN_set_word(Ri,BN_MASK2)) goto err;  /* Ri-- (mod word size) */
 			}
-		if (!BN_div(&Ri,NULL,&Ri,&tmod,ctx)) goto err;
+		if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
 		/* Ni = (R*Ri-1)/N,
 		 * keep only least significant word: */
-		mont->n0 = (Ri.top > 0) ? Ri.d[0] : 0;
-		BN_free(&Ri);
+		mont->n0 = (Ri->top > 0) ? Ri->d[0] : 0;
 		}
 #else /* !MONT_WORD */
 		{ /* bignum version */
@@ -317,13 +318,12 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
 		BN_zero(R);
 		if (!BN_set_bit(R,mont->ri)) goto err;  /* R = 2^ri */
 		                                        /* Ri = R^-1 mod N*/
-		if ((BN_mod_inverse(&Ri,R,&mont->N,ctx)) == NULL)
+		if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL)
 			goto err;
-		if (!BN_lshift(&Ri,&Ri,mont->ri)) goto err; /* R*Ri */
-		if (!BN_sub_word(&Ri,1)) goto err;
+		if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */
+		if (!BN_sub_word(Ri,1)) goto err;
 							/* Ni = (R*Ri-1) / N */
-		if (!BN_div(&(mont->Ni),NULL,&Ri,&mont->N,ctx)) goto err;
-		BN_free(&Ri);
+		if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err;
 		}
 #endif
 
@@ -332,9 +332,10 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
 	if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
 	if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;
 
-	return(1);
+	ret = 1;
 err:
-	return(0);
+	BN_CTX_end(ctx);
+	return ret;
 	}
 
 BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)

crypto/bn/bn_prime.c

@@ -159,15 +159,17 @@ int BN_GENCB_call(BN_GENCB *cb, int a, int b)
 int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe,
 	const BIGNUM *add, const BIGNUM *rem, BN_GENCB *cb)
 	{
-	BIGNUM t;
+	BIGNUM *t;
 	int found=0;
 	int i,j,c1=0;
 	BN_CTX *ctx;
 	int checks = BN_prime_checks_for_size(bits);
 
-	BN_init(&t);
 	ctx=BN_CTX_new();
 	if (ctx == NULL) goto err;
+	BN_CTX_start(ctx);
+	t = BN_CTX_get(ctx);
+	if(!t) goto err;
 loop: 
 	/* make a random number and set the top and bottom bits */
 	if (add == NULL)
@@ -204,7 +206,7 @@ loop:
 		 * check that (p-1)/2 is prime.
 		 * Since a prime is odd, We just
 		 * need to divide by 2 */
-		if (!BN_rshift1(&t,ret)) goto err;
+		if (!BN_rshift1(t,ret)) goto err;
 
 		for (i=0; i<checks; i++)
 			{
@@ -212,7 +214,7 @@ loop:
 			if (j == -1) goto err;
 			if (j == 0) goto loop;
 
-			j=BN_is_prime_fasttest_ex(&t,1,ctx,0,cb);
+			j=BN_is_prime_fasttest_ex(t,1,ctx,0,cb);
 			if (j == -1) goto err;
 			if (j == 0) goto loop;
 
@@ -224,8 +226,11 @@ loop:
 	/* we have a prime :-) */
 	found = 1;
 err:
-	BN_free(&t);
-	if (ctx != NULL) BN_CTX_free(ctx);
+	if (ctx != NULL)
+		{
+		BN_CTX_end(ctx);
+		BN_CTX_free(ctx);
+		}
 	bn_check_top(ret);
 	return found;
 	}

crypto/bn/bn_recp.c

@@ -217,17 +217,18 @@ err:
 int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
 	{
 	int ret= -1;
-	BIGNUM t;
+	BIGNUM *t;
 
-	BN_init(&t);
+	BN_CTX_start(ctx);
+	if((t = BN_CTX_get(ctx)) == NULL) goto err;
 
-	if (!BN_set_bit(&t,len)) goto err;
+	if (!BN_set_bit(t,len)) goto err;
 
-	if (!BN_div(r,NULL,&t,m,ctx)) goto err;
+	if (!BN_div(r,NULL,t,m,ctx)) goto err;
 
 	ret=len;
 err:
-	BN_free(&t);
 	bn_check_top(r);
+	BN_CTX_end(ctx);
 	return(ret);
 	}