[PATCH Xenial SRU] ntp: Fix ADJ_SETOFFSET being used w/ ADJ_NANO

[tim.gardner at canonical.com]

From: John Stultz <john.stultz at linaro.org>

BugLink: http://bugs.launchpad.net/bugs/1566465

Recently, in commit 37cf4dc3370f I forgot to check if the timeval being passed
was actually a timespec (as is signaled with ADJ_NANO).

This resulted in that patch breaking ADJ_SETOFFSET users who set
ADJ_NANO, by rejecting valid timespecs that were compared with
valid timeval ranges.

This patch addresses this by checking for the ADJ_NANO flag and
using the timepsec check instead in that case.

Reported-by: Harald Hoyer <harald at redhat.com>
Reported-by: Kay Sievers <kay at vrfy.org>
Fixes: 37cf4dc3370f "time: Verify time values in adjtimex ADJ_SETOFFSET to avoid overflow"
Signed-off-by: John Stultz <john.stultz at linaro.org>
Cc: Sasha Levin <sasha.levin at oracle.com>
Cc: Richard Cochran <richardcochran at gmail.com>
Cc: Prarit Bhargava <prarit at redhat.com>
Cc: David Herrmann <dh.herrmann at gmail.com>
Link: http://lkml.kernel.org/r/1453417415-19110-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
(cherry picked from commit dd4e17ab704269bce71402285f5e8b9ac24b1eff)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 kernel/time/ntp.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index d7654e2..ab86177 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -679,8 +679,18 @@ int ntp_validate_timex(struct timex *txc)
 		if (!capable(CAP_SYS_TIME))
 			return -EPERM;
 
-		if (!timeval_inject_offset_valid(&txc->time))
-			return -EINVAL;
+		if (txc->modes & ADJ_NANO) {
+			struct timespec ts;
+
+			ts.tv_sec = txc->time.tv_sec;
+			ts.tv_nsec = txc->time.tv_usec;
+			if (!timespec_inject_offset_valid(&ts))
+				return -EINVAL;
+
+		} else {
+			if (!timeval_inject_offset_valid(&txc->time))
+				return -EINVAL;
+		}
 	}
 
 	/*
-- 
1.9.1