Commit 5e5aeb43 authored Dec 03, 2014 by Sasha Levin Committed by John Stultz Jan 07, 2015

time: adjtimex: Validate the ADJ_FREQUENCY values



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>
Cc: stable <stable@vger.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>

parent 6ada1fc0

kernel/time/ntp.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -633,6 +633,13 @@ 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;
		}