linux-kernel - [PATCH 1/6] UML - Deal with host time going backwards

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080603190235.GA9511@c2.user-mode-linux.org>
Date:	Tue, 3 Jun 2008 15:02:35 -0400
From:	Jeff Dike <jdike@...toit.com>
To:	Andrew Morton <akpm@...l.org>, LKML <linux-kernel@...r.kernel.org>,
	uml-devel <user-mode-linux-devel@...ts.sourceforge.net>
Cc:	Nix <nix@...eri.org.uk>
Subject: [PATCH 1/6] UML - Deal with host time going backwards

Protection against the host's time going backwards - keep track of the
time at the last tick and if it's greater than the current time, keep
time stopped until the host catches up.

Cc: Nix <nix@...eri.org.uk>
Signed-off-by: Jeff Dike <jdike@...ux.intel.com>
---
 arch/um/os-Linux/time.c |    7 +++++++
 1 file changed, 7 insertions(+)

Index: linux-2.6-git/arch/um/os-Linux/time.c
===================================================================
--- linux-2.6-git.orig/arch/um/os-Linux/time.c	2008-05-14 10:44:02.000000000 -0400
+++ linux-2.6-git/arch/um/os-Linux/time.c	2008-06-02 15:43:53.000000000 -0400
@@ -106,6 +106,10 @@ static void deliver_alarm(void)
 	unsigned long long this_tick = os_nsecs();
 	int one_tick = UM_NSEC_PER_SEC / UM_HZ;
 
+	/* Protection against the host's time going backwards */
+	if ((last_tick != 0) && (this_tick < last_tick))
+		this_tick = last_tick;
+
 	if (last_tick == 0)
 		last_tick = this_tick - one_tick;
 
@@ -148,6 +152,9 @@ static int after_sleep_interval(struct t
 		start_usecs = usec;
 
 	start_usecs -= skew / UM_NSEC_PER_USEC;
+	if (start_usecs < 0)
+		start_usecs = 0;
+
 	tv = ((struct timeval) { .tv_sec  = start_usecs / UM_USEC_PER_SEC,
 				 .tv_usec = start_usecs % UM_USEC_PER_SEC });
 	interval = ((struct itimerval) { { 0, usec }, tv });
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/