From: Juergen Perlinger <perlinger@ntp.org>
Date: Tue, 1 Mar 2016 07:30:22 +0000 (+0100)
Subject: [Bug 3023] ntpdate cannot correct dates in the future.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9a9c1cfa2494e51e39894bebe3a67ffd635b6ace;p=thirdparty%2Fntp.git

[Bug 3023] ntpdate cannot correct dates in the future.

bk: 56d5450ekhNG9y81GxG7ZyYK483rXw
---

diff --git a/ChangeLog b/ChangeLog
index c70fe8fc5..1eecb8c7a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,7 @@
 
 * [Bug 2994] Systems with HAVE_SIGNALED_IO fail to compile. perlinger@ntp.org
 * [Bug 2995] Fixes to compile on Windows
+* [Bug 3023] ntpdate cannot correct dates in the future. perlinger@ntp.org
 
 ---
 (4.2.8p6) 2016/01/20 Released by Harlan Stenn <stenn@ntp.org>
diff --git a/ntpdate/ntpdate.c b/ntpdate/ntpdate.c
index a4271605c..be39cb030 100644
--- a/ntpdate/ntpdate.c
+++ b/ntpdate/ntpdate.c
@@ -1247,7 +1247,6 @@ static int
 clock_adjust(void)
 {
 	register struct server *sp, *server;
-	s_fp absoffset;
 	int dostep;
 
 	for (sp = sys_servers; sp != NULL; sp = sp->next_server)
@@ -1270,10 +1269,15 @@ clock_adjust(void)
 	} else if (never_step) {
 		dostep = 0;
 	} else {
-		absoffset = server->soffset;
-		if (absoffset < 0)
-			absoffset = -absoffset;
-		dostep = (absoffset >= NTPDATE_THRESHOLD || absoffset < 0);
+		/* [Bug 3023] get absolute difference, avoiding signed
+		 * integer overflow like hell.
+		 */
+		u_fp absoffset;
+		if (server->soffset < 0)
+			absoffset = 1u + (u_fp)(-(server->soffset + 1));
+		else
+			absoffset = (u_fp)server->soffset;
+		dostep = (absoffset >= NTPDATE_THRESHOLD);
 	}
 
 	if (dostep) {