Added NULL check to BN_clear() & BN_CTX_end()

Reviewed-by: NPaul Dale <paul.dale@oracle.com>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8518)

(cherry picked from commit ce1415ed2ce15305356cd028bcf7b9bc688d6d5c)

crypto/bn/bn_ctx.c

@@ -194,6 +194,8 @@ void BN_CTX_start(BN_CTX *ctx)
 
 void BN_CTX_end(BN_CTX *ctx)
 {
+    if (ctx == NULL)
+        return;
     CTXDBG_ENTRY("BN_CTX_end", ctx);
     if (ctx->err_stack)
         ctx->err_stack--;

crypto/bn/bn_lib.c

@@ -338,6 +338,8 @@ void BN_swap(BIGNUM *a, BIGNUM *b)
 
 void BN_clear(BIGNUM *a)
 {
+    if (a == NULL)
+        return;
     bn_check_top(a);
     if (a->d != NULL)
         OPENSSL_cleanse(a->d, sizeof(*a->d) * a->dmax);

crypto/bn/bn_prime.c

@@ -135,7 +135,6 @@ int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe,
     found = 1;
  err:
     OPENSSL_free(mods);
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     bn_check_top(ret);

crypto/dh/dh_check.c

@@ -58,10 +58,8 @@ int DH_check_params(const DH *dh, int *ret)
 
     ok = 1;
  err:
-    if (ctx != NULL) {
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
-    }
     return ok;
 }
 
@@ -171,10 +169,8 @@ int DH_check(const DH *dh, int *ret)
     }
     ok = 1;
  err:
-    if (ctx != NULL) {
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
-    }
     return ok;
 }
 
@@ -225,9 +221,7 @@ int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
 
     ok = 1;
  err:
-    if (ctx != NULL) {
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
-    }
     return ok;
 }

crypto/dh/dh_gen.c

@@ -122,9 +122,7 @@ static int dh_builtin_genparams(DH *ret, int prime_len, int generator,
         ok = 0;
     }
 
-    if (ctx != NULL) {
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
-    }
     return ok;
 }

crypto/dh/dh_key.c

@@ -205,10 +205,8 @@ static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
 
     ret = BN_bn2bin(tmp, key);
  err:
-    if (ctx != NULL) {
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
-    }
     return ret;
 }
 

crypto/dsa/dsa_gen.c

@@ -292,7 +292,6 @@ int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
         if (seed_out)
             memcpy(seed_out, seed, qsize);
     }
-    if (ctx)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     BN_MONT_CTX_free(mont);
@@ -607,7 +606,6 @@ int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
     OPENSSL_free(seed);
     if (seed_out != seed_tmp)
         OPENSSL_free(seed_tmp);
-    if (ctx)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     BN_MONT_CTX_free(mont);

crypto/ec/ec2_smpl.c

@@ -204,7 +204,6 @@ int ec_GF2m_simple_group_check_discriminant(const EC_GROUP *group,
     ret = 1;
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
     return ret;

crypto/ec/ec_lib.c

@@ -1074,7 +1074,6 @@ static int ec_field_inverse_mod_ord(const EC_GROUP *group, BIGNUM *r,
     ret = 1;
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
     return ret;

crypto/ec/ec_mult.c

@@ -948,7 +948,6 @@ int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
     ret = 1;
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
     EC_ec_pre_comp_free(pre_comp);

crypto/ec/ecdh_ossl.c

@@ -113,7 +113,6 @@ int ecdh_simple_compute_key(unsigned char **pout, size_t *poutlen,
 
  err:
     EC_POINT_clear_free(tmp);
-    if (ctx)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     OPENSSL_free(buf);

crypto/ec/ecp_nistz256.c

@@ -888,7 +888,6 @@ __owur static int ecp_nistz256_mult_precompute(EC_GROUP *group, BN_CTX *ctx)
     ret = 1;
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
 

crypto/ec/ecp_smpl.c

@@ -307,7 +307,6 @@ int ec_GFp_simple_group_check_discriminant(const EC_GROUP *group, BN_CTX *ctx)
     ret = 1;
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
     return ret;
@@ -787,7 +786,6 @@ int ec_GFp_simple_add(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a,
     ret = 1;
 
  end:
-    if (ctx)                    /* otherwise we already called BN_CTX_end */
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
     return ret;

crypto/rsa/rsa_gen.c

@@ -387,7 +387,6 @@ static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value,
         RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
         ok = 0;
     }
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     return ok;

crypto/rsa/rsa_ossl.c

@@ -148,7 +148,6 @@ static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
      */
     r = BN_bn2binpad(ret, to, num);
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     OPENSSL_clear_free(buf, num);
@@ -354,7 +353,6 @@ static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
      */
     r = BN_bn2binpad(res, to, num);
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     OPENSSL_clear_free(buf, num);
@@ -484,7 +482,6 @@ static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
     err_clear_last_constant_time(r >= 0);
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     OPENSSL_clear_free(buf, num);
@@ -581,7 +578,6 @@ static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
         RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 
  err:
-    if (ctx != NULL)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     OPENSSL_clear_free(buf, num);

crypto/rsa/rsa_x931g.c

@@ -133,7 +133,6 @@ int RSA_X931_derive_ex(RSA *rsa, BIGNUM *p1, BIGNUM *p2, BIGNUM *q1,
 
     ret = 1;
  err:
-    if (ctx)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);
     BN_CTX_free(ctx2);
@@ -188,7 +187,6 @@ int RSA_X931_generate_key_ex(RSA *rsa, int bits, const BIGNUM *e,
     ok = 1;
 
  error:
-    if (ctx)
     BN_CTX_end(ctx);
     BN_CTX_free(ctx);