From 8cd9da85d2bd87ce889043e7b1735723dd10eb89 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 13 Sep 2021 16:53:32 +0200 Subject: [PATCH] posix-cpu-timers: Prevent spuriously armed 0-value itimer Resetting/stopping an itimer eventually leads to it being reprogrammed with an actual "0" value. As a result the itimer expires on the next tick, triggering an unexpected signal. To fix this, make sure that struct signal_struct::it[CPUCLOCK_PROF/VIRT]::expires is set to 0 when setitimer() passes a 0 it_value, indicating that the timer must stop. Fixes: 406dd42bd1ba ("posix-cpu-timers: Force next expiration recalc after itimer reset") Reported-by: Victor Stinner Reported-by: Chris Hixon Signed-off-by: Frederic Weisbecker Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210913145332.232023-1-frederic@kernel.org --- kernel/time/posix-cpu-timers.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index ee736861b18f..643d412ac623 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1404,7 +1404,8 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid, } } - *newval += now; + if (*newval) + *newval += now; } /*