diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2009-12-09 14:19:31 +0000 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2010-10-30 08:45:25 -0400 |
| commit | 3c80fe4ac9cfb13b1bfa4edf1544e8b656716694 (patch) | |
| tree | c605435b642323cd76eea9567a43d8c67b9c9db1 /kernel | |
| parent | f7a998a9491f2da1d3e44d150aa611d10093da4f (diff) | |
audit: Call tty_audit_push_task() outside preempt disabled
While auditing all tasklist_lock read_lock sites I stumbled over the
following call chain:
audit_prepare_user_tty()
read_lock(&tasklist_lock);
tty_audit_push_task();
mutex_lock(&buf->mutex);
--> buf->mutex is locked with preemption disabled.
Solve this by acquiring a reference to the task struct under
rcu_read_lock and call tty_audit_push_task outside of the preempt
disabled region.
Move all code which needs to be protected by sighand lock into
tty_audit_push_task() and use lock/unlock_sighand as we do not hold
tasklist_lock.
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: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/audit.c | 25 |
1 files changed, 9 insertions, 16 deletions
diff --git a/kernel/audit.c b/kernel/audit.c index a300931fc45f..8429afea37bf 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -467,23 +467,16 @@ static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid) struct task_struct *tsk; int err; - read_lock(&tasklist_lock); + rcu_read_lock(); tsk = find_task_by_vpid(pid); - err = -ESRCH; - if (!tsk) - goto out; - err = 0; - - spin_lock_irq(&tsk->sighand->siglock); - if (!tsk->signal->audit_tty) - err = -EPERM; - spin_unlock_irq(&tsk->sighand->siglock); - if (err) - goto out; - - tty_audit_push_task(tsk, loginuid, sessionid); -out: - read_unlock(&tasklist_lock); + if (!tsk) { + rcu_read_unlock(); + return -ESRCH; + } + get_task_struct(tsk); + rcu_read_unlock(); + err = tty_audit_push_task(tsk, loginuid, sessionid); + put_task_struct(tsk); return err; } |