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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 20D28C4332F for ; Mon, 20 Sep 2021 18:14:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0AD1161B42 for ; Mon, 20 Sep 2021 18:14:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376947AbhITSO7 (ORCPT ); Mon, 20 Sep 2021 14:14:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:35774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1359289AbhITSJ1 (ORCPT ); Mon, 20 Sep 2021 14:09:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0A9FB63268; Mon, 20 Sep 2021 17:19:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632158360; bh=jLUQ1CvSAsfGGbAHf8ONc8i1Cp+aV+Ji4h/vvvknEEI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hra0FxtkGelPAqrUZvAj44bCTThm1Nob2/qQPc+WVges4Emy60OKaTUnnINy2gYVc QclH3NcF8ZNPFJoENDn0g6JUdzlfcbSOPcRP/DktKKDjnWmjR8nPWbZ+L6ldNQJxRS nqCVbKhXKP6hQxfHk1/XU0parlpr8vaWxn0lAhBY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Brooke Basile , "Bryan ODonoghue" , Felipe Balbi , Lorenzo Colitti , =?UTF-8?q?Maciej=20=C5=BBenczykowski?= , Sasha Levin Subject: [PATCH 5.4 089/260] usb: gadget: u_ether: fix a potential null pointer dereference Date: Mon, 20 Sep 2021 18:41:47 +0200 Message-Id: <20210920163934.165034442@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163931.123590023@linuxfoundation.org> References: <20210920163931.123590023@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: linux-kernel@vger.kernel.org From: Maciej Żenczykowski [ Upstream commit 8ae01239609b29ec2eff55967c8e0fe3650cfa09 ] f_ncm tx timeout can call us with null skb to flush a pending frame. In this case skb is NULL to begin with but ceases to be null after dev->wrap() completes. In such a case in->maxpacket will be read, even though we've failed to check that 'in' is not NULL. Though I've never observed this fail in practice, however the 'flush operation' simply does not make sense with a null usb IN endpoint - there's nowhere to flush to... (note that we're the gadget/device, and IN is from the point of view of the host, so here IN actually means outbound...) Cc: Brooke Basile Cc: "Bryan O'Donoghue" Cc: Felipe Balbi Cc: Greg Kroah-Hartman Cc: Lorenzo Colitti Signed-off-by: Maciej Żenczykowski Link: https://lore.kernel.org/r/20210701114834.884597-6-zenczykowski@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/u_ether.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index 99b840daf3d9..57da62e33184 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -491,8 +491,9 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb, } spin_unlock_irqrestore(&dev->lock, flags); - if (skb && !in) { - dev_kfree_skb_any(skb); + if (!in) { + if (skb) + dev_kfree_skb_any(skb); return NETDEV_TX_OK; } -- 2.30.2