sched, signals: fix the racy usage of ->signal in account_group_xxx/run_posix_cpu_timers

[linux-2.6-omap-h63xx.git] / kernel / posix-cpu-timers.c

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 153dcb2639c3df614c7862041a9d485b7dbe6614..895337b16a24e7b9df95e8a9306b224bbe000971 100644 (file)
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1308,9 +1308,10 @@ static inline int task_cputime_expired(const struct task_cputime *sample,
  */
 static inline int fastpath_timer_check(struct task_struct *tsk)
 {
-       struct signal_struct *sig = tsk->signal;
+       struct signal_struct *sig;
 
-       if (unlikely(!sig))
+       /* tsk == current, ensure it is safe to use ->signal/sighand */
+       if (unlikely(tsk->exit_state))
                return 0;
 
        if (!task_cputime_zero(&tsk->cputime_expires)) {
@@ -1323,6 +1324,8 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
                if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
                        return 1;
        }
+
+       sig = tsk->signal;
        if (!task_cputime_zero(&sig->cputime_expires)) {
                struct task_cputime group_sample;