From: Christian Göttsche <cgzones@googlemail.com>
Date: Tue, 24 Jan 2023 14:44:35 +0000 (+0100)
Subject: Modernize manual memzero implementation
X-Git-Tag: 4.14.0-rc1~226
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e0d79ee0320b337510aee5734579973597653df6;p=thirdparty%2Fshadow.git

Modernize manual memzero implementation

Instead of using volatile pointers to prevent the compiler from
optimizing the call away, use a memory barrier.
This requires support for embedded assembly, which should be fine after
the recent requirement bumps.
---

diff --git a/lib/defines.h b/lib/defines.h
index 54053103a..d3416f119 100644
--- a/lib/defines.h
+++ b/lib/defines.h
@@ -54,10 +54,8 @@
 #else					/* !HAVE_MEMSET_S && HAVE_EXPLICIT_BZERO */
 static inline void memzero(void *ptr, size_t size)
 {
-	volatile unsigned char * volatile p = ptr;
-	while (size--) {
-		*p++ = '\0';
-	}
+	ptr = memset(ptr, '\0', size);
+	__asm__ __volatile__ ("" : : "r"(ptr) : "memory");
 }
 #endif					/* !HAVE_MEMSET_S && !HAVE_EXPLICIT_BZERO */