The patch titled
Subject: posix-cpu-timers: fix nanosleep task_struct leak
has been added to the -mm tree. Its filename is
posix-cpu-timers-fix-nanosleep-task_struct-leak.patch
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From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Subject: posix-cpu-timers: fix nanosleep task_struct leak
In do_cpu_nanosleep() we do posic_cpu_timer_create(), but forgot
corresponding posix_cpu_timer_del() what lead to task_struct leak.
This looks like a DoS problem fix, since it's possible to eat kernel
memory (very slowly though) by normal user, hence Cc stable.
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Reported-by: Tommi Rantala <tt.rantala@xxxxxxxxx>
Tested-by: Tommi Rantala <tt.rantala@xxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/posix-cpu-timers.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff -puN kernel/posix-cpu-timers.c~posix-cpu-timers-fix-nanosleep-task_struct-leak kernel/posix-cpu-timers.c
--- a/kernel/posix-cpu-timers.c~posix-cpu-timers-fix-nanosleep-task_struct-leak
+++ a/kernel/posix-cpu-timers.c
@@ -1417,8 +1417,10 @@ static int do_cpu_nanosleep(const clocki
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;
}
@@ -1436,9 +1438,26 @@ static int do_cpu_nanosleep(const clocki
* 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.
_
Patches currently in -mm which might be from sgruszka@xxxxxxxxxx are
linux-next.patch
posix-cpu-timers-fix-nanosleep-task_struct-leak.patch
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