ntp: Verify offset doesn't overflow in ntp_update_offset
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>
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 149cc80..125fc03 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -297,15 +297,17 @@
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