mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-05 20:04:19 +08:00
fix dangling zombie when new parent ignores children
This fixes an arcane bug that we think was a regression introduced
by commit b2b2cbc4b2
. When a parent
ignores SIGCHLD (or uses SA_NOCLDWAIT), its children would self-reap
but they don't if it's using ptrace on them. When the parent thread
later exits and ceases to ptrace a child but leaves other live
threads in the parent's thread group, any zombie children are left
dangling. The fix makes them self-reap then, as they would have
done earlier if ptrace had not been in use.
Signed-off-by: Roland McGrath <roland@redhat.com>
This commit is contained in:
parent
14dd0b8141
commit
666f164f4f
@ -702,6 +702,23 @@ static void exit_mm(struct task_struct * tsk)
|
||||
mmput(mm);
|
||||
}
|
||||
|
||||
/*
|
||||
* Return nonzero if @parent's children should reap themselves.
|
||||
*
|
||||
* Called with write_lock_irq(&tasklist_lock) held.
|
||||
*/
|
||||
static int ignoring_children(struct task_struct *parent)
|
||||
{
|
||||
int ret;
|
||||
struct sighand_struct *psig = parent->sighand;
|
||||
unsigned long flags;
|
||||
spin_lock_irqsave(&psig->siglock, flags);
|
||||
ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
|
||||
(psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT));
|
||||
spin_unlock_irqrestore(&psig->siglock, flags);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* Detach all tasks we were using ptrace on.
|
||||
* Any that need to be release_task'd are put on the @dead list.
|
||||
@ -711,6 +728,7 @@ static void exit_mm(struct task_struct * tsk)
|
||||
static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
|
||||
{
|
||||
struct task_struct *p, *n;
|
||||
int ign = -1;
|
||||
|
||||
list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
|
||||
__ptrace_unlink(p);
|
||||
@ -726,10 +744,18 @@ static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
|
||||
* release_task() here because we already hold tasklist_lock.
|
||||
*
|
||||
* 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.
|
||||
*/
|
||||
if (!task_detached(p) && thread_group_empty(p)) {
|
||||
if (!same_thread_group(p->real_parent, parent))
|
||||
do_notify_parent(p, p->exit_signal);
|
||||
else {
|
||||
if (ign < 0)
|
||||
ign = ignoring_children(parent);
|
||||
if (ign)
|
||||
p->exit_signal = -1;
|
||||
}
|
||||
}
|
||||
|
||||
if (task_detached(p)) {
|
||||
|
Loading…
Reference in New Issue
Block a user