fix error found by coverity: check if ctx is != NULL before calling BN_CTX_end()

[openssl.git] / crypto / ec / ec2_smpl.c

diff --git a/crypto/ec/ec2_smpl.c b/crypto/ec/ec2_smpl.c
index 1132c8e5afa828333202066c3d0309a583504b0e..5cd1eac41fc33bb1bf435f4fc6d606870b0c8f85 100644 (file)
--- a/crypto/ec/ec2_smpl.c
+++ b/crypto/ec/ec2_smpl.c
@@ -281,7 +281,8 @@ int ec_GF2m_simple_group_check_discriminant(const EC_GROUP *group, BN_CTX *ctx)
        ret = 1;
 
 err:
-       BN_CTX_end(ctx);
+       if (ctx != NULL)
+               BN_CTX_end(ctx);
        if (new_ctx != NULL)
                BN_CTX_free(new_ctx);
        return ret;
@@ -354,11 +355,11 @@ int ec_GF2m_simple_point_set_affine_coordinates(const EC_GROUP *group, EC_POINT
                }
 
        if (!BN_copy(&point->X, x)) goto err;
-       BN_set_sign(&point->X, 0);
+       BN_set_negative(&point->X, 0);
        if (!BN_copy(&point->Y, y)) goto err;
-       BN_set_sign(&point->Y, 0);
+       BN_set_negative(&point->Y, 0);
        if (!BN_copy(&point->Z, BN_value_one())) goto err;
-       BN_set_sign(&point->Z, 0);
+       BN_set_negative(&point->Z, 0);
        point->Z_is_one = 1;
        ret = 1;
 
@@ -389,12 +390,12 @@ int ec_GF2m_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_
        if (x != NULL)
                {
                if (!BN_copy(x, &point->X)) goto err;
-               BN_set_sign(x, 0);
+               BN_set_negative(x, 0);
                }
        if (y != NULL)
                {
                if (!BN_copy(y, &point->Y)) goto err;
-               BN_set_sign(y, 0);
+               BN_set_negative(y, 0);
                }
        ret = 1;
                
@@ -575,7 +576,7 @@ int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
                }
        form = buf[0];
        y_bit = form & 1;
-       form = form & ~1;
+       form = form & ~1U;
        if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
                && (form != POINT_CONVERSION_UNCOMPRESSED)
                && (form != POINT_CONVERSION_HYBRID))
@@ -805,13 +806,18 @@ int ec_GF2m_simple_is_at_infinity(const EC_GROUP *group, const EC_POINT *point)
  */
 int ec_GF2m_simple_is_on_curve(const EC_GROUP *group, const EC_POINT *point, BN_CTX *ctx)
        {
-       BN_CTX *new_ctx = NULL;
-       BIGNUM *rh, *lh, *tmp1;
        int ret = -1;
+       BN_CTX *new_ctx = NULL;
+       BIGNUM *lh, *y2;
+       int (*field_mul)(const EC_GROUP *, BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
+       int (*field_sqr)(const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
 
        if (EC_POINT_is_at_infinity(group, point))
                return 1;
-       
+
+       field_mul = group->meth->field_mul;
+       field_sqr = group->meth->field_sqr;     
+
        /* only support affine coordinates */
        if (!point->Z_is_one) goto err;
 
@@ -823,37 +829,23 @@ int ec_GF2m_simple_is_on_curve(const EC_GROUP *group, const EC_POINT *point, BN_
                }
 
        BN_CTX_start(ctx);
-       rh = BN_CTX_get(ctx);
+       y2 = BN_CTX_get(ctx);
        lh = BN_CTX_get(ctx);
-       tmp1 = BN_CTX_get(ctx);
-       if (tmp1 == NULL) goto err;
+       if (lh == NULL) goto err;
 
        /* We have a curve defined by a Weierstrass equation
         *      y^2 + x*y = x^3 + a*x^2 + b.
-        * To test this, we add up the right-hand side in 'rh'
-        * and the left-hand side in 'lh'.
+        *  <=> x^3 + a*x^2 + x*y + b + y^2 = 0
+        *  <=> ((x + a) * x + y ) * x + b + y^2 = 0
         */
-
-       /* rh := X^3 */
-       if (!group->meth->field_sqr(group, tmp1, &point->X, ctx)) goto err;
-       if (!group->meth->field_mul(group, rh, tmp1, &point->X, ctx)) goto err;
-
-       /* rh := rh + a*X^2 */
-       if (!group->meth->field_mul(group, tmp1, tmp1, &group->a, ctx)) goto err;
-       if (!BN_GF2m_add(rh, rh, tmp1)) goto err;
-
-       /* rh := rh + b */
-       if (!BN_GF2m_add(rh, rh, &group->b)) goto err;
-
-       /* lh := Y^2 */
-       if (!group->meth->field_sqr(group, lh, &point->Y, ctx)) goto err;
-
-       /* lh := lh + x*y */
-       if (!group->meth->field_mul(group, tmp1, &point->X, &point->Y, ctx)) goto err;
-       if (!BN_GF2m_add(lh, lh, tmp1)) goto err;
-
-       ret = (0 == BN_GF2m_cmp(lh, rh));
-
+       if (!BN_GF2m_add(lh, &point->X, &group->a)) goto err;
+       if (!field_mul(group, lh, lh, &point->X, ctx)) goto err;
+       if (!BN_GF2m_add(lh, lh, &point->Y)) goto err;
+       if (!field_mul(group, lh, lh, &point->X, ctx)) goto err;
+       if (!BN_GF2m_add(lh, lh, &group->b)) goto err;
+       if (!field_sqr(group, y2, &point->Y, ctx)) goto err;
+       if (!BN_GF2m_add(lh, lh, y2)) goto err;
+       ret = BN_is_zero(lh);
  err:
        if (ctx) BN_CTX_end(ctx);
        if (new_ctx) BN_CTX_free(new_ctx);