From: Oleg Nesterov <oleg@tv-sign.ru>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Pavel Emelyanov <xemul@openvz.org>,
Roland McGrath <roland@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] wait_task_continued/zombie: don't use task_pid_nr_ns() lockless
Date: Sat, 24 Nov 2007 19:59:34 +0300 [thread overview]
Message-ID: <20071124165934.GA8033@tv-sign.ru> (raw)
Surprise, other 2 wait_task_() functions also abuse task_pid_nr_ns(). May cause
read-after-free or report nr == 0 in wait_task_continued(). wait_task_zombie()
doesn't have this problem, but still it is better to cache pid_t rather than
call task_pid_nr_ns() 3 times on the saved pid_namespace.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- PT/kernel/exit.c~PID 2007-11-24 18:17:20.000000000 +0300
+++ PT/kernel/exit.c 2007-11-24 19:28:11.000000000 +0300
@@ -1186,12 +1186,9 @@ static int wait_task_zombie(struct task_
{
unsigned long state;
int retval, status, traced;
- struct pid_namespace *ns;
-
- ns = current->nsproxy->pid_ns;
+ pid_t pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
if (unlikely(noreap)) {
- pid_t pid = task_pid_nr_ns(p, ns);
uid_t uid = p->uid;
int exit_code = p->exit_code;
int why, status;
@@ -1310,11 +1307,11 @@ static int wait_task_zombie(struct task_
retval = put_user(status, &infop->si_status);
}
if (!retval && infop)
- retval = put_user(task_pid_nr_ns(p, ns), &infop->si_pid);
+ retval = put_user(pid, &infop->si_pid);
if (!retval && infop)
retval = put_user(p->uid, &infop->si_uid);
if (!retval)
- retval = task_pid_nr_ns(p, ns);
+ retval = pid;
if (traced) {
write_lock_irq(&tasklist_lock);
@@ -1433,7 +1430,6 @@ static int wait_task_continued(struct ta
int retval;
pid_t pid;
uid_t uid;
- struct pid_namespace *ns;
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
return 0;
@@ -1448,8 +1444,7 @@ static int wait_task_continued(struct ta
p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
spin_unlock_irq(&p->sighand->siglock);
- ns = current->nsproxy->pid_ns;
- pid = task_pid_nr_ns(p, ns);
+ pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
uid = p->uid;
get_task_struct(p);
read_unlock(&tasklist_lock);
@@ -1460,7 +1455,7 @@ static int wait_task_continued(struct ta
if (!retval && stat_addr)
retval = put_user(0xffff, stat_addr);
if (!retval)
- retval = task_pid_nr_ns(p, ns);
+ retval = pid;
} else {
retval = wait_noreap_copyout(p, pid, uid,
CLD_CONTINUED, SIGCONT,
reply other threads:[~2007-11-24 16:59 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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