ntp: Verify offset doesn't overflow in ntp_update_offset (52d189f1) · Commits · 戴 / test

We need to make sure that the offset is valid before manipulating it, otherwise it might overflow on the multiplication. Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by:

Sasha Levin <sasha.levin@oracle.com> [jstultz: Reworked one of the checks so it makes more sense] Signed-off-by:

John Stultz <john.stultz@linaro.org>

kernel/time/ntp.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -297,15 +297,17 @@ static void ntp_update_offset(long offset)
		if (!(time_status & STA_PLL))
		return;

		if (!(time_status & STA_NANO))
		if (!(time_status & STA_NANO)) {
		/* Make sure the multiplication below won't overflow */
		offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
		offset *= NSEC_PER_USEC;
		}

		/*
		* Scale the phase adjustment and
		* clamp to the operating range.
		*/
		offset = min(offset, MAXPHASE);
		offset = max(offset, -MAXPHASE);
		offset = clamp(offset, -MAXPHASE, MAXPHASE);

		/*
		* Select how the frequency is to be controlled

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