From patchwork Wed Mar 2 21:03:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergey Shtylyov X-Patchwork-Id: 547753 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21FECC433F5 for ; Wed, 2 Mar 2022 21:03:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242079AbiCBVD6 (ORCPT ); Wed, 2 Mar 2022 16:03:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232218AbiCBVD4 (ORCPT ); Wed, 2 Mar 2022 16:03:56 -0500 Received: from mxout04.lancloud.ru (mxout04.lancloud.ru [45.84.86.114]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED60B9FEE for ; Wed, 2 Mar 2022 13:03:06 -0800 (PST) Received: from LanCloud DKIM-Filter: OpenDKIM Filter v2.11.0 mxout04.lancloud.ru 8736A20ADE83 Received: from LanCloud Received: from LanCloud Received: from LanCloud From: Sergey Shtylyov Subject: [PATCH] usb: host: xhci-dbgtty: fix check in dbc_tty_write() To: Mathias Nyman , , "Greg Kroah-Hartman" Organization: Open Mobile Platform Message-ID: Date: Thu, 3 Mar 2022 00:03:01 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 Content-Language: en-US X-Originating-IP: [192.168.11.198] X-ClientProxiedBy: LFEXT02.lancloud.ru (fd00:f066::142) To LFEX1907.lancloud.ru (fd00:f066::207) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The 'int count' parameter of the tty write() method gets assigned to *unsigned long* local variable in the fifo_in() macro which implies a problematic type cast. Fix the 'count' check before the fifo_in() invocation to account for the signed type of the 'count' parameter... Found by Linux Verification Center (linuxtesting.org) with the SVACE static analysis tool. Signed-off-by: Sergey Shtylyov --- drivers/usb/host/xhci-dbgtty.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: usb/drivers/usb/host/xhci-dbgtty.c =================================================================== --- usb.orig/drivers/usb/host/xhci-dbgtty.c +++ usb/drivers/usb/host/xhci-dbgtty.c @@ -216,7 +216,7 @@ static int dbc_tty_write(struct tty_stru unsigned long flags; spin_lock_irqsave(&port->port_lock, flags); - if (count) + if (count > 0) count = kfifo_in(&port->write_fifo, buf, count); dbc_start_tx(port); spin_unlock_irqrestore(&port->port_lock, flags);