Merge branch 'linux-linaro-lsk-v4.4-android' of git://git.linaro.org/kernel/linux...

[firefly-linux-kernel-4.4.55.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a46c40bfb5f669f04f6b42c8c06ea0c61ba63360..c7e8ed99c953d282a0cbddac2d558a5927dbfeae 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -151,11 +151,17 @@ static void ptrace_unfreeze_traced(struct task_struct *task)
 
        WARN_ON(!task->ptrace || task->parent != current);
 
+       /*
+        * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
+        * Recheck state under the lock to close this race.
+        */
        spin_lock_irq(&task->sighand->siglock);
-       if (__fatal_signal_pending(task))
-               wake_up_state(task, __TASK_TRACED);
-       else
-               task->state = TASK_TRACED;
+       if (task->state == __TASK_TRACED) {
+               if (__fatal_signal_pending(task))
+                       wake_up_state(task, __TASK_TRACED);
+               else
+                       task->state = TASK_TRACED;
+       }
        spin_unlock_irq(&task->sighand->siglock);
 }