From: Noah Misch <noah@leadboat.com>
Date: Mon, 2 Feb 2015 15:00:45 +0000 (-0500)
Subject: Prevent Valgrind Memcheck errors around px_acquire_system_randomness().
X-Git-Tag: REL9_4_1~3
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ca84dfa90e9929737bda7393f88b488cb7161147;p=postgresql

Prevent Valgrind Memcheck errors around px_acquire_system_randomness().

This function uses uninitialized stack and heap buffers as supplementary
entropy sources.  Mark them so Memcheck will not complain.  Back-patch
to 9.4, where Valgrind Memcheck cooperation first appeared.

Marko Tiikkaja
---

diff --git a/contrib/pgcrypto/random.c b/contrib/pgcrypto/random.c
index 3f092ca346..d72679e412 100644
--- a/contrib/pgcrypto/random.c
+++ b/contrib/pgcrypto/random.c
@@ -32,6 +32,7 @@
 #include "postgres.h"
 
 #include "px.h"
+#include "utils/memdebug.h"
 
 /* how many bytes to ask from system random provider */
 #define RND_BYTES  32
@@ -195,7 +196,7 @@ try_unix_std(uint8 *dst)
 	memcpy(dst, (uint8 *) &x, sizeof(x));
 	dst += sizeof(x);
 
-	/* let's be desperate */
+	/* hash of uninitialized stack and heap allocations */
 	res = px_find_digest("sha1", &md);
 	if (res >= 0)
 	{
@@ -203,8 +204,10 @@ try_unix_std(uint8 *dst)
 		uint8		stack[8192];
 		int			alloc = 32 * 1024;
 
+		VALGRIND_MAKE_MEM_DEFINED(stack, sizeof(stack));
 		px_md_update(md, stack, sizeof(stack));
 		ptr = px_alloc(alloc);
+		VALGRIND_MAKE_MEM_DEFINED(ptr, alloc);
 		px_md_update(md, ptr, alloc);
 		px_free(ptr);