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Commit 692117c1 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

posix-cpu-timers: Sanitize bogus WARNONS 



Warning when p == NULL and then proceeding and dereferencing p does not
make any sense as the kernel will crash with a NULL pointer dereference
right away.

Bailing out when p == NULL and returning an error code does not cure the
underlying problem which caused p to be NULL. Though it might allow to
do proper debugging.

Same applies to the clock id check in set_process_cpu_timer().

Clean them up and make them return without trying to do further damage.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190819143801.846497772@linutronix.de
parent 68b2c8c1

kernel/time/posix-cpu-timers.c

+13 −7
Original line number Diff line number Diff line
@@ -375,7 +375,8 @@ static int posix_cpu_timer_del(struct k_itimer *timer) 
	struct sighand_struct *sighand;

	struct task_struct *p = timer->it.cpu.task;



	WARN_ON_ONCE(p == NULL);

	if (WARN_ON_ONCE(!p))

		return -EINVAL;



	/*

	 * Protect against sighand release/switch in exit/exec and process/
@@ -581,7 +582,8 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, 
	u64 old_expires, new_expires, old_incr, val;

	int ret;



	WARN_ON_ONCE(p == NULL);

	if (WARN_ON_ONCE(!p))

		return -EINVAL;



	/*

	 * Use the to_ktime conversion because that clamps the maximum
@@ -716,10 +718,11 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, 


static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)

{

	u64 now;

	struct task_struct *p = timer->it.cpu.task;

	u64 now;



	WARN_ON_ONCE(p == NULL);

	if (WARN_ON_ONCE(!p))

		return;



	/*

	 * Easy part: convert the reload time.
@@ -1001,12 +1004,13 @@ static void check_process_timers(struct task_struct *tsk, 
 */

static void posix_cpu_timer_rearm(struct k_itimer *timer)

{

	struct task_struct *p = timer->it.cpu.task;

	struct sighand_struct *sighand;

	unsigned long flags;

	struct task_struct *p = timer->it.cpu.task;

	u64 now;



	WARN_ON_ONCE(p == NULL);

	if (WARN_ON_ONCE(!p))

		return;



	/*

	 * Fetch the current sample and update the timer's expiry time.
@@ -1203,7 +1207,9 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, 
	u64 now;

	int ret;



	WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);

	if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))

		return;



	ret = cpu_timer_sample_group(clock_idx, tsk, &now);



	if (oldval && ret != -EINVAL) {