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 63505C433F5 for ; Mon, 20 Sep 2021 17:52:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C99761159 for ; Mon, 20 Sep 2021 17:52:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352109AbhITRxf (ORCPT ); Mon, 20 Sep 2021 13:53:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:53088 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353844AbhITRrW (ORCPT ); Mon, 20 Sep 2021 13:47:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CDE2861B98; Mon, 20 Sep 2021 17:10:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632157855; bh=7ogRByi+HrVU9OAaW3OXKVjyZ76yXdlPY3Ky+LKYRHY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Bk5zdBWUosetAUQIGVJBfWtEFOjv1IAvkTlpwFwobFbW4HStWi3BbWBuuzA36mLSb WBIteP1Zn8WoiURoBEZEIYo8rt1f8hsus2ghPMQTn4vkl+fdtsc67jHcj1vE9ehWRS ePIUBMkpuBzpdpCeUM54DZlP+mQF6M4/qLRXP/48= 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 4.19 183/293] usb: gadget: u_ether: fix a potential null pointer dereference Date: Mon, 20 Sep 2021 18:42:25 +0200 Message-Id: <20210920163939.538394252@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163933.258815435@linuxfoundation.org> References: <20210920163933.258815435@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 156651df6b4d..d7a12161e553 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