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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E838C433EF for ; Mon, 11 Oct 2021 13:49:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8517060C49 for ; Mon, 11 Oct 2021 13:49:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237243AbhJKNvJ (ORCPT ); Mon, 11 Oct 2021 09:51:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:38778 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237246AbhJKNuO (ORCPT ); Mon, 11 Oct 2021 09:50:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 70AF960F21; Mon, 11 Oct 2021 13:48:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1633960094; bh=90j3KqDcIJeIiJ/g/3FQopNbkD1LE4QJBm6HsNbOlU0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FBMgW5JFwMmYYXXYlvNYtMcy5sSpFNXRf/s6ya90zzhGQ4tgPG9f1pc7kyuvPat3C uSQ1IyUm3WQgqiXVOgBc9HgTQAcqi4LxFwmkVvaPNsYLEGU+wPgXn6KPqyGqNpyoys 9u9M+vgVko4krGe2zQAxy/f1bh4rRVcrz07fjLqM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oliver Neukum , Johan Hovold Subject: [PATCH 5.4 02/52] USB: cdc-acm: fix racy tty buffer accesses Date: Mon, 11 Oct 2021 15:45:31 +0200 Message-Id: <20211011134503.803461169@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211011134503.715740503@linuxfoundation.org> References: <20211011134503.715740503@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Johan Hovold commit 65a205e6113506e69a503b61d97efec43fc10fd7 upstream. A recent change that started reporting break events to the line discipline caused the tty-buffer insertions to no longer be serialised by inserting events also from the completion handler for the interrupt endpoint. Completion calls for distinct endpoints are not guaranteed to be serialised. For example, in case a host-controller driver uses bottom-half completion, the interrupt and bulk-in completion handlers can end up running in parallel on two CPUs (high-and low-prio tasklets, respectively) thereby breaking the tty layer's single producer assumption. Fix this by holding the read lock also when inserting characters from the bulk endpoint. Fixes: 08dff274edda ("cdc-acm: fix BREAK rx code path adding necessary calls") Cc: stable@vger.kernel.org Acked-by: Oliver Neukum Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210929090937.7410-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -474,11 +474,16 @@ static int acm_submit_read_urbs(struct a static void acm_process_read_urb(struct acm *acm, struct urb *urb) { + unsigned long flags; + if (!urb->actual_length) return; + spin_lock_irqsave(&acm->read_lock, flags); tty_insert_flip_string(&acm->port, urb->transfer_buffer, urb->actual_length); + spin_unlock_irqrestore(&acm->read_lock, flags); + tty_flip_buffer_push(&acm->port); }