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From 79a3977cdff6edfb2de5d661f8e894aabfd742a4 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 9 Dec 2009 14:33:48 +0100
Subject: [PATCH] audit: Use rcu for task lookup protection
commit 378cc63c24b6c9b9269c05475fbefeb8335790b3 in tip.
Protect the task lookups in audit_receive_msg() with rcu_read_lock()
instead of tasklist_lock and use lock/unlock_sighand to protect
against the exit race.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
kernel/audit.c | 30 ++++++++++++++----------------
1 files changed, 14 insertions(+), 16 deletions(-)
diff --git a/kernel/audit.c b/kernel/audit.c
index 3d04a64..4ac4746 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -881,17 +881,16 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
case AUDIT_TTY_GET: {
struct audit_tty_status s;
struct task_struct *tsk;
+ unsigned long flags;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
tsk = find_task_by_vpid(pid);
- if (!tsk)
- err = -ESRCH;
- else {
- spin_lock_irq(&tsk->sighand->siglock);
+ if (tsk && lock_task_sighand(tsk, &flags)) {
s.enabled = tsk->signal->audit_tty != 0;
- spin_unlock_irq(&tsk->sighand->siglock);
- }
- read_unlock(&tasklist_lock);
+ unlock_task_sighand(tsk, &flags);
+ } else
+ err = -ESRCH;
+ rcu_read_unlock();
if (!err)
audit_send_reply(NETLINK_CB(skb).pid, seq,
@@ -901,22 +900,21 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
case AUDIT_TTY_SET: {
struct audit_tty_status *s;
struct task_struct *tsk;
+ unsigned long flags;
if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
return -EINVAL;
s = data;
if (s->enabled != 0 && s->enabled != 1)
return -EINVAL;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
tsk = find_task_by_vpid(pid);
- if (!tsk)
- err = -ESRCH;
- else {
- spin_lock_irq(&tsk->sighand->siglock);
+ if (tsk && lock_task_sighand(tsk, &flags)) {
tsk->signal->audit_tty = s->enabled != 0;
- spin_unlock_irq(&tsk->sighand->siglock);
- }
- read_unlock(&tasklist_lock);
+ unlock_task_sighand(tsk, &flags);
+ } else
+ err = -ESRCH;
+ rcu_read_unlock();
break;
}
default:
--
1.7.0.4
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