From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933025Ab2JDVSw (ORCPT ); Thu, 4 Oct 2012 17:18:52 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:44231 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932858Ab2JDVSl (ORCPT ); Thu, 4 Oct 2012 17:18:41 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Russ Gorby , "Yin, Fengwei" , Alan Cox Subject: [ 39/56] n_gsm: added interlocking for gsm_data_lock for certain code paths Date: Thu, 4 Oct 2012 14:16:00 -0700 Message-Id: <20121004211156.562748779@linuxfoundation.org> X-Mailer: git-send-email 1.7.12.2.421.g261b511 In-Reply-To: <20121004211152.101901246@linuxfoundation.org> References: <20121004211152.101901246@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russ Gorby commit 5e44708f75b0f8712da715d6babb0c21089b2317 upstream. There were some locking holes in the management of the MUX's message queue for 2 code paths: 1) gsmld_write_wakeup 2) receipt of CMD_FCON flow-control message In both cases gsm_data_kick is called w/o locking so it can collide with other other instances of gsm_data_kick (pulling messages tx_tail) or potentially other instances of __gsm_data_queu (adding messages to tx_head) Changed to take the tx_lock in these 2 cases Signed-off-by: Russ Gorby Tested-by: Yin, Fengwei Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1193,6 +1193,8 @@ static void gsm_control_message(struct g u8 *data, int clen) { u8 buf[1]; + unsigned long flags; + switch (command) { case CMD_CLD: { struct gsm_dlci *dlci = gsm->dlci[0]; @@ -1218,7 +1220,9 @@ static void gsm_control_message(struct g gsm->constipated = 0; gsm_control_reply(gsm, CMD_FCOFF, NULL, 0); /* Kick the link in case it is idling */ + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_data_kick(gsm); + spin_unlock_irqrestore(&gsm->tx_lock, flags); break; case CMD_MSC: /* Out of band modem line change indicator for a DLCI */ @@ -2380,12 +2384,12 @@ static void gsmld_write_wakeup(struct tt /* Queue poll */ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); + spin_lock_irqsave(&gsm->tx_lock, flags); gsm_data_kick(gsm); if (gsm->tx_bytes < TX_THRESH_LO) { - spin_lock_irqsave(&gsm->tx_lock, flags); gsm_dlci_data_sweep(gsm); - spin_unlock_irqrestore(&gsm->tx_lock, flags); } + spin_unlock_irqrestore(&gsm->tx_lock, flags); } /**