From: Sasha Levin <[email protected]> We need to make sure that the offset is valid before manipulating it, otherwise it might overflow on the multiplication.
Cc: Sasha Levin <[email protected]> Cc: Richard Cochran <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Sasha Levin <[email protected]> [jstultz: Reworked one of the checks so it makes more sense] Signed-off-by: John Stultz <[email protected]> --- v2: Reworked the overflow clamp to make more sense. 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 149cc80..125fc03 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 -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
