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Message-ID: <20091201182202.GA12754@redhat.com>
Date: Tue, 1 Dec 2009 19:22:02 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...e.hu>,
Christoph Hellwig <hch@...radead.org>,
Nick Piggin <npiggin@...e.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Al Viro <viro@...iv.linux.org.uk>,
James Morris <jmorris@...ei.org>
Subject: Re: [PATCH] audit: Call tty_audit_push_task() outside preempt
disabled region
On 12/01, Thomas Gleixner wrote:
>
> -void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
> +int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
> {
> - struct tty_audit_buf *buf;
> + struct tty_audit_buf *buf = NULL;
> + unsigned long flags;
>
> - spin_lock_irq(&tsk->sighand->siglock);
> - buf = tsk->signal->tty_audit_buf;
> - if (buf)
> + if (!lock_task_sighand(tsk, &flags))
> + return -ESRCH;
> +
> + if (tsk->signal->audit_tty && tsk->signal->tty_audit_buf) {
> + buf = tsk->signal->tty_audit_buf;
> atomic_inc(&buf->count);
> - spin_unlock_irq(&tsk->sighand->siglock);
> + }
> + unlock_task_sighand(tsk, &flags);
> +
> if (!buf)
> - return;
> + return -EPERM;
I think the patch is correct, but it changes the behaviour of
audit_prepare_user_tty() a bit.
Suppose that signal->audit_tty != NULL but signal->tty_audit_buf
is not allocated yet. In this audit_prepare_user_tty() returns 0
before the patch and -EPERM after.
I do not know if this matters, just to be sure this is OK.
Oleg.
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