From 52d189f1b38810b1b483d5bac2e4fa90b9afd372 Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Thu, 3 Dec 2015 15:46:48 -0500 Subject: [PATCH] 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 Cc: Richard Cochran Cc: Thomas Gleixner Signed-off-by: Sasha Levin [jstultz: Reworked one of the checks so it makes more sense] Signed-off-by: John Stultz --- kernel/time/ntp.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 149cc8086aea..125fc0342355 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -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 -- 2.20.1