Replace (sometimes conditional) use of alloca with malloc, and clearing

through volatile pointers with explicit_bzero().

ok beck@ jsing@

1 files changed, 0 insertions, 16 deletions

diff --git a/src/lib/libcrypto/bn/bn_exp.c b/src/lib/libcrypto/bn/bn_exp.c
index 5d9263e01e..a27373c97b 100644
--- a/src/lib/libcrypto/bn/bn_exp.c
+++ b/src/lib/libcrypto/bn/bn_exp.c
@@ -114,11 +114,6 @@
 #include "bn_lcl.h"
 
 #include <stdlib.h>
-#if defined(__GNUC__)
-# ifndef alloca
-#  define alloca(s) __builtin_alloca((s))
-# endif
-#endif
 
 /* maximum precomputation table size for *variable* sliding windows */
 #define TABLE_SIZE      32
@@ -632,12 +627,6 @@ BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
         numPowers = 1 << window;
         powerbufLen = sizeof(m->d[0]) * (top * numPowers +
             ((2*top) > numPowers ? (2*top) : numPowers));
-#ifdef alloca
-        if (powerbufLen < 3072)
-                powerbufFree = alloca(powerbufLen +
-                    MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
-        else
-#endif
         if ((powerbufFree = (unsigned char*)malloc(powerbufLen +
             MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
                 goto err;
@@ -645,11 +634,6 @@ BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
         powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
         memset(powerbuf, 0, powerbufLen);
 
-#ifdef alloca
-        if (powerbufLen < 3072)
-                powerbufFree = NULL;
-#endif
-
         /* lay down tmp and am right after powers table */
         tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0]) * top * numPowers);
         am.d = tmp.d + top;