bn_exp.c: improve portability.

diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index 5b00aa1e3c5b2c1503a776e424e0a3cc0a14a155..aae00491db21202ef1e484fa98837f8a1b7914fd 100644 (file)
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -654,16 +654,21 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
        numPowers = 1 << window;
        powerbufLen = sizeof(m->d[0])*(top*numPowers +
                                (top>numPowers?top:numPowers));
+#ifdef alloca
        if (powerbufLen < 3072)
                powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
-       else if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
+       else
+#endif
+       if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
                goto err;
                
        powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
        memset(powerbuf, 0, powerbufLen);
 
+#ifdef alloca
        if (powerbufLen < 3072)
                powerbufFree = NULL;
+#endif
 
        computeTemp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);
        computeTemp.top = computeTemp.dmax = top;