From ab263f47c9781a644de8b28013434b645082922e Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 9 Dec 2009 14:19:41 +0000 Subject: [PATCH] audit: Use rcu for task lookup protection 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 Cc: Al Viro Cc: Eric Paris Cc: Oleg Nesterov Signed-off-by: Al Viro --- kernel/audit.c | 30 ++++++++++++++---------------- 1 file changed, 14 insertions(+), 16 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index 57f4038694d1..77770a034d59 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -873,17 +873,16 @@ 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, @@ -893,22 +892,21 @@ 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: -- 2.20.1