For tip/timers/urgent. Additional validation of adjtimex freq values to avoid potential multiplication overflows were added in commit 5e5aeb4367b (time: adjtimex: Validate the ADJ_FREQUENCY values) Unfortunately the patch used LONG_MAX/MIN instead of LLONG_MAX/MIN, which was fine on 64bit systems, but being much smaller on 32bit systems caused false positives resulting in most direct frequency adjustments to fail w/ EINVAL. ntpd only does direct frequency adjustments at startup, so the issue was not as easily observed there, but other time sync applications like ptpd and chrony were more effected by the bug. See bugs: https://bugzilla.kernel.org/show_bug.cgi?id=92481 https://bugzilla.redhat.com/show_bug.cgi?id=1188074 This patch changes the checks to use LLONG_MAX for clarity, and additionally the checks are disabled on 32bit systems since LLONG_MAX/PPM_SCALE is always larger then the 32bit long freq value, so mult overflows aren't possible there. Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Sasha Levin <sasha.levin@xxxxxxxxxx> Cc: Richard Cochran <richardcochran@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Reported-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx> Reported-by: George Joseph <george.joseph@xxxxxxxxxxxxx> Tested-by: George Joseph <george.joseph@xxxxxxxxxxxxx> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> --- v2: Included the BITS_PER_LONG check to disable the check on 32bit systems, since it generates build warnings in some settings. kernel/time/ntp.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 28bf91c..6824ef9 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -633,10 +633,14 @@ 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) + /* + * Check for potential mult overflows that can + * only happen on 64bit systems. + */ + if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) { + if (LLONG_MIN / PPM_SCALE > txc->freq) return -EINVAL; - if (LONG_MAX / PPM_SCALE < txc->freq) + if (LLONG_MAX / PPM_SCALE < txc->freq) return -EINVAL; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html