If the tracer went away (may_ptrace_stop() failed), ptrace_stop() drops tasklist
and then changes the ->state from TASK_TRACED to TASK_RUNNING.
This can fool another tracer which attaches to us in between. Change the ->state
under tasklist_lock to ensure that ptrace_check_attach() can't wrongly succeed.
Also, remove the unnecessary mb().
Signed-off-by: Oleg Nesterov <[email protected]>
--- PT/kernel/signal.c~1_ptrace_stop 2007-11-21 21:41:02.000000000 +0300
+++ PT/kernel/signal.c 2007-11-22 16:59:35.000000000 +0300
@@ -1628,11 +1628,11 @@ static void ptrace_stop(int exit_code, i
} else {
/*
* By the time we got the lock, our tracer went away.
- * Don't stop here.
+ * Don't drop the lock yet, another tracer may come.
*/
- read_unlock(&tasklist_lock);
- set_current_state(TASK_RUNNING);
+ __set_current_state(TASK_RUNNING);
current->exit_code = nostop_code;
+ read_unlock(&tasklist_lock);
}
/*
-
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