In do_cpu_nanosleep() we do posic_cpu_timer_create(), but forgot
corresponding posix_cpu_timer_del() what lead to task_struct leak.
Reported-and-tested-by: Tommi Rantala <tt.rant...@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgrus...@redhat.com>
Cc: sta...@vger.kernel.org
---
v1 -> v2: add comments
This looks like DoS problem fix, since it's possible to eat kernel
memory (very slowly though) by normal user, hence Cc stable.
kernel/posix-cpu-timers.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index a278cad..942ca27 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1401,8 +1401,10 @@ static int do_cpu_nanosleep(const clockid_t which_clock,
int flags,
while (!signal_pending(current)) {
if (timer.it.cpu.expires.sched == 0) {
/*
- * Our timer fired and was reset.
+ * Our timer fired and was reset, below
+ * deletion can not fail.
*/
+ posix_cpu_timer_del(&timer);
spin_unlock_irq(&timer.it_lock);
return 0;
}
@@ -1420,9 +1422,26 @@ static int do_cpu_nanosleep(const clockid_t which_clock,
int flags,
* We were interrupted by a signal.
*/
sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
- posix_cpu_timer_set(&timer, 0, &zero_it, it);
+ error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
+ if (!error) {
+ /*
+ * Timer is now unarmed, deletion can not fail.
+ */
+ posix_cpu_timer_del(&timer);
+ }
spin_unlock_irq(&timer.it_lock);
+ while (error == TIMER_RETRY) {
+ /*
+ * We need to handle case when timer was or is in the
+ * middle of firing. In other cases we already freed
+ * resources.
+ */
+ spin_lock_irq(&timer.it_lock);
+ error = posix_cpu_timer_del(&timer);
+ spin_unlock_irq(&timer.it_lock);
+ }
+
if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
/*
* It actually did fire already.
--
1.7.11.7
--
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