From: Sasha Levin <sasha.levin@oracle.com>
Date: Thu, 4 Dec 2014 00:25:05 +0000 (-0500)
Subject: time: adjtimex: Validate the ADJ_FREQUENCY values
X-Git-Tag: firefly_0821_release~3679^2~916
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2497402c9ad62e91897fed5310f7df48bf3bca1f;p=firefly-linux-kernel-4.4.55.git

time: adjtimex: Validate the ADJ_FREQUENCY values

commit 5e5aeb4367b450a28f447f6d5ab57d8f2ab16a5f upstream.

Verify that the frequency value from userspace is valid and makes sense.

Unverified values can cause overflows later on.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
[jstultz: Fix up bug for negative values and drop redunent cap check]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index af8d1d4f3d55..28db9bedc857 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -631,6 +631,13 @@ int ntp_validate_timex(struct timex *txc)
 	if ((txc->modes & ADJ_SETOFFSET) && (!capable(CAP_SYS_TIME)))
 		return -EPERM;
 
+	if (txc->modes & ADJ_FREQUENCY) {
+		if (LONG_MIN / PPM_SCALE > txc->freq)
+			return -EINVAL;
+		if (LONG_MAX / PPM_SCALE < txc->freq)
+			return -EINVAL;
+	}
+
 	return 0;
 }