From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7CD4C433DF for ; Tue, 18 Aug 2020 09:55:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7726206B5 for ; Tue, 18 Aug 2020 09:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597744523; bh=CWV8qKqmg4/yZ7b/ssYmI+NKnTUM3pt0+7XKWgSKpRg=; h=Subject:To:From:Date:List-ID:From; b=JKtAxvV0JY51uQ3mzRPAmEiLzjFBJlma2YG1lwXqABKCiWvBhPRE4LDrA+NdmV7ic 8G+O7Y2act1BgOj04eGn+2lHcVIRRuawml9s92KalnkEOC9EkcE1adZ5vXIxih6Dty 5K+MbDMCqBopVu4T3kgL1tTMj9iwH6O/bnhvcmDA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726370AbgHRJzX (ORCPT ); Tue, 18 Aug 2020 05:55:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:49446 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726043AbgHRJzV (ORCPT ); Tue, 18 Aug 2020 05:55:21 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B1ED4206B5; Tue, 18 Aug 2020 09:55:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597744520; bh=CWV8qKqmg4/yZ7b/ssYmI+NKnTUM3pt0+7XKWgSKpRg=; h=Subject:To:From:Date:From; b=2bsL40gOoga8UxKHtqdV/7xBFvCG2KZY2CMej7YDahbeZjRWhzcLfX9E+XQ8j0sSH GlNnx5zlPOoEzuxmhq/i66u2DHjGVjsHV5Em/Wfe8JVpvP/+l3Z1GeSpAyg23AXRwJ QxiE7wgJDLqZgnpMBzHHXc7tYiyv9Z+bGzRRj1rA= Subject: patch "USB: cdc-acm: rework notification_buffer resizing" added to usb-linus To: trix@redhat.com, gregkh@linuxfoundation.org, oneukum@suse.com, stable@vger.kernel.org From: Date: Tue, 18 Aug 2020 11:55:42 +0200 Message-ID: <1597744542124212@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled USB: cdc-acm: rework notification_buffer resizing to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From f4b9d8a582f738c24ebeabce5cc15f4b8159d74e Mon Sep 17 00:00:00 2001 From: Tom Rix Date: Sat, 1 Aug 2020 08:21:54 -0700 Subject: USB: cdc-acm: rework notification_buffer resizing Clang static analysis reports this error cdc-acm.c:409:3: warning: Use of memory after it is freed acm_process_notification(acm, (unsigned char *)dr); There are three problems, the first one is that dr is not reset The variable dr is set with if (acm->nb_index) dr = (struct usb_cdc_notification *)acm->notification_buffer; But if the notification_buffer is too small it is resized with if (acm->nb_size) { kfree(acm->notification_buffer); acm->nb_size = 0; } alloc_size = roundup_pow_of_two(expected_size); /* * kmalloc ensures a valid notification_buffer after a * use of kfree in case the previous allocation was too * small. Final freeing is done on disconnect. */ acm->notification_buffer = kmalloc(alloc_size, GFP_ATOMIC); dr should point to the new acm->notification_buffer. The second problem is any data in the notification_buffer is lost when the pointer is freed. In the normal case, the current data is accumulated in the notification_buffer here. memcpy(&acm->notification_buffer[acm->nb_index], urb->transfer_buffer, copy_size); When a resize happens, anything before notification_buffer[acm->nb_index] is garbage. The third problem is the acm->nb_index is not reset on a resizing buffer error. So switch resizing to using krealloc and reassign dr and reset nb_index. Fixes: ea2583529cd1 ("cdc-acm: reassemble fragmented notifications") Signed-off-by: Tom Rix Cc: stable Acked-by: Oliver Neukum Link: https://lore.kernel.org/r/20200801152154.20683-1-trix@redhat.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 991786876dbb..7f6f3ab5b8a6 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -378,21 +378,19 @@ static void acm_ctrl_irq(struct urb *urb) if (current_size < expected_size) { /* notification is transmitted fragmented, reassemble */ if (acm->nb_size < expected_size) { - if (acm->nb_size) { - kfree(acm->notification_buffer); - acm->nb_size = 0; - } + u8 *new_buffer; alloc_size = roundup_pow_of_two(expected_size); - /* - * kmalloc ensures a valid notification_buffer after a - * use of kfree in case the previous allocation was too - * small. Final freeing is done on disconnect. - */ - acm->notification_buffer = - kmalloc(alloc_size, GFP_ATOMIC); - if (!acm->notification_buffer) + /* Final freeing is done on disconnect. */ + new_buffer = krealloc(acm->notification_buffer, + alloc_size, GFP_ATOMIC); + if (!new_buffer) { + acm->nb_index = 0; goto exit; + } + + acm->notification_buffer = new_buffer; acm->nb_size = alloc_size; + dr = (struct usb_cdc_notification *)acm->notification_buffer; } copy_size = min(current_size, -- 2.28.0