[src/trunk]: src/sys/kern kern: Handle clock winding back in nanosleep1 witho...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f445e820ad51
branches:  trunk
changeset: 363474:f445e820ad51
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Mar 13 12:21:28 2022 +0000

description:
kern: Handle clock winding back in nanosleep1 without overflow.

Reported-by: syzbot+3bdd260582424a611946%syzkaller.appspotmail.com@localhost

diffstat:

 sys/kern/kern_time.c |  14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)

diffs (35 lines):

diff -r eae7618824f2 -r f445e820ad51 sys/kern/kern_time.c
--- a/sys/kern/kern_time.c      Sun Mar 13 11:35:47 2022 +0000
+++ b/sys/kern/kern_time.c      Sun Mar 13 12:21:28 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_time.c,v 1.212 2022/03/12 16:46:57 riastradh Exp $        */
+/*     $NetBSD: kern_time.c,v 1.213 2022/03/13 12:21:28 riastradh Exp $        */
 
 /*-
  * Copyright (c) 2000, 2004, 2005, 2007, 2008, 2009, 2020
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_time.c,v 1.212 2022/03/12 16:46:57 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_time.c,v 1.213 2022/03/13 12:21:28 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/resourcevar.h>
@@ -435,8 +435,14 @@
                if (flags & TIMER_ABSTIME) {
                        timespecsub(rqt, &rmtend, t);
                } else {
-                       timespecsub(&rmtend, &rmtstart, t);
-                       timespecsub(rqt, t, t);
+                       if (timespeccmp(&rmtend, &rmtstart, <))
+                               timespecclear(t); /* clock wound back */
+                       else
+                               timespecsub(&rmtend, &rmtstart, t);
+                       if (timespeccmp(rqt, t, <))
+                               timespecclear(t);
+                       else
+                               timespecsub(rqt, t, t);
                }
                if (t->tv_sec < 0)
                        timespecclear(t);