From: Adrien Zinger <zinger.ad@gmail.com>
Date: Wed, 20 Mar 2024 08:39:16 +0000 (+0100)
Subject: Fix GCC compilation -Waggressive-loop-optimizations
X-Git-Tag: openssl-3.3.3~64
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=579a06cea3685e7f739cdd7e8cd3c3efa1c0d7b7;p=thirdparty%2Fopenssl.git

Fix GCC compilation -Waggressive-loop-optimizations

GCC 13.1.0 were reporting a compilation warning with -O2/3 and
-Waggressive-loop-optimizations. GCC is raising an undefined behavior in the
while loop. Replace the while loop with a memset call at the top of the
function.

Fixes #21088

CLA: trivial

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23898)

(cherry picked from commit c45ca0656f8d1fe43b8cf444c88d295a063341ca)
---

diff --git a/crypto/bn/rsaz_exp_x2.c b/crypto/bn/rsaz_exp_x2.c
index 70705486a15..e9a8e3cbbd2 100644
--- a/crypto/bn/rsaz_exp_x2.c
+++ b/crypto/bn/rsaz_exp_x2.c
@@ -576,11 +576,7 @@ static void to_words52(BN_ULONG *out, int out_len,
         out_len--;
     }
 
-    while (out_len > 0) {
-        *out = 0;
-        out_len--;
-        out++;
-    }
+    memset(out, 0, out_len * sizeof(BN_ULONG));
 }
 
 static ossl_inline void put_digit(uint8_t *out, int out_len, uint64_t digit)