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-rw-r--r--kernel/ptrace.c103
1 files changed, 88 insertions, 15 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index c9cf48b..aaad0ec 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -60,11 +60,15 @@ static void ptrace_untrace(struct task_struct *child)
{
spin_lock(&child->sighand->siglock);
if (task_is_traced(child)) {
- if (child->signal->flags & SIGNAL_STOP_STOPPED) {
+ /*
+ * If the group stop is completed or in progress,
+ * this thread was already counted as stopped.
+ */
+ if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+ child->signal->group_stop_count)
__set_task_state(child, TASK_STOPPED);
- } else {
+ else
signal_wake_up(child, 1);
- }
}
spin_unlock(&child->sighand->siglock);
}
@@ -235,18 +239,58 @@ out:
return retval;
}
-static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
{
- child->exit_code = data;
- /* .. re-parent .. */
- __ptrace_unlink(child);
- /* .. and wake it up. */
- if (child->exit_state != EXIT_ZOMBIE)
- wake_up_process(child);
+ int ret;
+ spin_lock(&sigh->siglock);
+ ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+ (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+ spin_unlock(&sigh->siglock);
+ return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * If it's a zombie, our attachedness prevented normal parent notification
+ * or self-reaping. Do notification now if it would have happened earlier.
+ * If it should reap itself, return true.
+ *
+ * If it's our own child, there is no notification to do.
+ * But if our normal children self-reap, then this child
+ * was prevented by ptrace and we must reap it now.
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+ __ptrace_unlink(p);
+
+ if (p->exit_state == EXIT_ZOMBIE) {
+ if (!task_detached(p) && thread_group_empty(p)) {
+ if (!same_thread_group(p->real_parent, tracer))
+ do_notify_parent(p, p->exit_signal);
+ else if (ignoring_children(tracer->sighand))
+ p->exit_signal = -1;
+ }
+ if (task_detached(p)) {
+ /* Mark it as in the process of being reaped. */
+ p->exit_state = EXIT_DEAD;
+ return true;
+ }
+ }
+
+ return false;
}
int ptrace_detach(struct task_struct *child, unsigned int data)
{
+ bool dead = false;
+
if (!valid_signal(data))
return -EIO;
@@ -255,14 +299,45 @@ int ptrace_detach(struct task_struct *child, unsigned int data)
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
write_lock_irq(&tasklist_lock);
- /* protect against de_thread()->release_task() */
- if (child->ptrace)
- __ptrace_detach(child, data);
+ /*
+ * This child can be already killed. Make sure de_thread() or
+ * our sub-thread doing do_wait() didn't do release_task() yet.
+ */
+ if (child->ptrace) {
+ child->exit_code = data;
+ dead = __ptrace_detach(current, child);
+ }
write_unlock_irq(&tasklist_lock);
+ if (unlikely(dead))
+ release_task(child);
+
return 0;
}
+/*
+ * Detach all tasks we were using ptrace on.
+ */
+void exit_ptrace(struct task_struct *tracer)
+{
+ struct task_struct *p, *n;
+ LIST_HEAD(ptrace_dead);
+
+ write_lock_irq(&tasklist_lock);
+ list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+ if (__ptrace_detach(tracer, p))
+ list_add(&p->ptrace_entry, &ptrace_dead);
+ }
+ write_unlock_irq(&tasklist_lock);
+
+ BUG_ON(!list_empty(&tracer->ptraced));
+
+ list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+ list_del_init(&p->ptrace_entry);
+ release_task(p);
+ }
+}
+
int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
{
int copied = 0;
@@ -612,8 +687,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
goto out_put_task_struct;
ret = arch_ptrace(child, request, addr, data);
- if (ret < 0)
- goto out_put_task_struct;
out_put_task_struct:
put_task_struct(child);
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