Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751896AbbF1Avn (ORCPT ); Sat, 27 Jun 2015 20:51:43 -0400 Received: from mail-ig0-f178.google.com ([209.85.213.178]:38574 "EHLO mail-ig0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751188AbbF1Avi (ORCPT ); Sat, 27 Jun 2015 20:51:38 -0400 From: Patrick Donnelly To: Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org (open list) Cc: Patrick Donnelly Subject: [PATCH v2 1/2] tty: add missing rcu_read_lock for task_pgrp Date: Sat, 27 Jun 2015 20:51:28 -0400 Message-Id: <1435452689-25390-1-git-send-email-batrick@batbytes.com> X-Mailer: git-send-email 2.4.4 In-Reply-To: <1435439824-3975-1-git-send-email-batrick@batbytes.com> References: <1435439824-3975-1-git-send-email-batrick@batbytes.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1858 Lines: 70 task_pgrp requires an rcu or tasklist lock to be obtained if the returned pid is to be dereferenced, which kill_pgrp does. Obtain an RCU lock for the duration of use. Signed-off-by: Patrick Donnelly --- drivers/tty/tty_io.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 57fc6ee..fbb55db 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -388,33 +388,39 @@ EXPORT_SYMBOL_GPL(tty_find_polling_driver); int tty_check_change(struct tty_struct *tty) { unsigned long flags; + struct pid *pgrp; int ret = 0; if (current->signal->tty != tty) return 0; - spin_lock_irqsave(&tty->ctrl_lock, flags); + rcu_read_lock(); + pgrp = task_pgrp(current); + spin_lock_irqsave(&tty->ctrl_lock, flags); if (!tty->pgrp) { printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n"); - goto out_unlock; + goto out_irqunlock; } - if (task_pgrp(current) == tty->pgrp) - goto out_unlock; + if (pgrp == tty->pgrp) + goto out_irqunlock; spin_unlock_irqrestore(&tty->ctrl_lock, flags); + if (is_ignored(SIGTTOU)) - goto out; + goto out_rcuunlock; if (is_current_pgrp_orphaned()) { ret = -EIO; - goto out; + goto out_rcuunlock; } - kill_pgrp(task_pgrp(current), SIGTTOU, 1); + kill_pgrp(pgrp, SIGTTOU, 1); + rcu_read_unlock(); set_thread_flag(TIF_SIGPENDING); ret = -ERESTARTSYS; -out: return ret; -out_unlock: +out_irqunlock: spin_unlock_irqrestore(&tty->ctrl_lock, flags); +out_rcuunlock: + rcu_read_unlock(); return ret; } -- Patrick Donnelly -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/