From: Frederic Weisbecker frederic@kernel.org
commit e2a71bdea81690b6ef11f4368261ec6f5b6891aa upstream.
When an expiration delta falls into the last level of the wheel, that delta has be compared against the maximum possible delay and reduced to fit in if necessary.
However instead of comparing the delta against the maximum, the code compares the actual expiry against the maximum. Then instead of fixing the delta to fit in, it sets the maximum delta as the expiry value.
This can result in various undesired outcomes, the worst possible one being a timer expiring 15 days ahead to fire immediately.
Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel") Signed-off-by: Frederic Weisbecker frederic@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20200717140551.29076-2-frederic@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/time/timer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -500,8 +500,8 @@ static int calc_wheel_index(unsigned lon * Force expire obscene large timeouts to expire at the * capacity limit of the wheel. */ - if (expires >= WHEEL_TIMEOUT_CUTOFF) - expires = WHEEL_TIMEOUT_MAX; + if (delta >= WHEEL_TIMEOUT_CUTOFF) + expires = clk + WHEEL_TIMEOUT_MAX;
idx = calc_index(expires, LVL_DEPTH - 1); }