Fix Coverity logically dead code.
*/
#include <openssl/opensslconf.h>
+#include <openssl/crypto.h>
#include "rsaz_exp.h"
#ifndef RSAZ_ENABLED
@@ -404,14 +405,23 @@ int RSAZ_mod_exp_x2_ifma256(BN_ULONG *out,
/* Exponentiation */
{
- int rem = modulus_bitsize % exp_win_size;
- int delta = rem ? rem : exp_win_size;
- BN_ULONG table_idx_mask = exp_win_mask;
+ const int rem = modulus_bitsize % exp_win_size;
+ const BN_ULONG table_idx_mask = exp_win_mask;
- int exp_bit_no = modulus_bitsize - delta;
+ int exp_bit_no = modulus_bitsize - rem;
int exp_chunk_no = exp_bit_no / 64;
int exp_chunk_shift = exp_bit_no % 64;
+ /*
+ * If rem == 0, then
+ * exp_bit_no = modulus_bitsize - exp_win_size
+ * However, this isn't possible because rem is { 1024, 1536, 2048 } % 5
+ * which is { 4, 1, 3 } respectively.
+ *
+ * If this assertion ever fails the fix above is easy.
+ */
+ OPENSSL_assert(rem != 0);
+
/* Process 1-st exp window - just init result */
BN_ULONG red_table_idx_0 = expz[exp_chunk_no + 0 * (exp_digits + 1)];
BN_ULONG red_table_idx_1 = expz[exp_chunk_no + 1 * (exp_digits + 1)];
