Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758711AbbFCMr5 (ORCPT ); Wed, 3 Jun 2015 08:47:57 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58036 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755400AbbFCMS7 (ORCPT ); Wed, 3 Jun 2015 08:18:59 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pan Xinhui , Jiri Slaby Subject: [PATCH 4.0 083/148] tty/n_gsm.c: fix a memory leak when gsmtty is removed Date: Wed, 3 Jun 2015 21:09:13 +0900 Message-Id: <20150603114208.987397959@linuxfoundation.org> X-Mailer: git-send-email 2.4.2 In-Reply-To: <20150603114205.337615117@linuxfoundation.org> References: <20150603114205.337615117@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2306 Lines: 70 4.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pan Xinhui commit 8f9cfeed3eae86c70d3b04445a6f2036b27b6304 upstream. when gsmtty_remove put dlci, it will cause memory leak if dlci->port's refcount is zero. So we do the cleanup work in .cleanup callback instead. dlci will be last put in two call chains. 1) gsmld_close -> gsm_cleanup_mux -> gsm_dlci_release -> dlci_put 2) gsmld_remove -> dlci_put so there is a race. the memory leak depends on the race. In call chain 2. we hit the memory leak. below comment tells. release_tty -> tty_driver_remove_tty -> gsmtty_remove -> dlci_put -> tty_port_destructor (WARN_ON(port->itty) and return directly) | tty->port->itty = NULL; | tty_kref_put ---> release_one_tty -> gsmtty_cleanup (added by our patch) So our patch fix the memory leak by doing the cleanup work after tty core did. Signed-off-by: Pan Xinhui Fixes: dfabf7ffa30585 Acked-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -3170,7 +3170,7 @@ static int gsmtty_break_ctl(struct tty_s return gsmtty_modem_update(dlci, encode); } -static void gsmtty_remove(struct tty_driver *driver, struct tty_struct *tty) +static void gsmtty_cleanup(struct tty_struct *tty) { struct gsm_dlci *dlci = tty->driver_data; struct gsm_mux *gsm = dlci->gsm; @@ -3178,7 +3178,6 @@ static void gsmtty_remove(struct tty_dri dlci_put(dlci); dlci_put(gsm->dlci[0]); mux_put(gsm); - driver->ttys[tty->index] = NULL; } /* Virtual ttys for the demux */ @@ -3199,7 +3198,7 @@ static const struct tty_operations gsmtt .tiocmget = gsmtty_tiocmget, .tiocmset = gsmtty_tiocmset, .break_ctl = gsmtty_break_ctl, - .remove = gsmtty_remove, + .cleanup = gsmtty_cleanup, }; -- 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/