Messages in this thread Patch in this message | | | Date | Mon, 19 Aug 2019 16:31:46 +0200 | From | Thomas Gleixner <> | Subject | [patch 05/44] posix-cpu-timers: Sanitize bogus WARNONS |
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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: Thomas Gleixner <tglx@linutronix.de> --- kernel/time/posix-cpu-timers.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-)
--- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -375,7 +375,8 @@ static int posix_cpu_timer_del(struct k_ 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_ 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_ 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 */ 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_s 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) {
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