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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 137FBC4727C for ; Thu, 9 Sep 2021 13:06:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F24E26115B for ; Thu, 9 Sep 2021 13:06:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358078AbhIINGH (ORCPT ); Thu, 9 Sep 2021 09:06:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:57782 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356154AbhIIMxL (ORCPT ); Thu, 9 Sep 2021 08:53:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 00FE16137B; Thu, 9 Sep 2021 11:57:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631188662; bh=7ogRByi+HrVU9OAaW3OXKVjyZ76yXdlPY3Ky+LKYRHY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SdKBL25t3OR/jLWKXeBnsiRKn3b26gJqwQgKnG1LOxXMtN/zCll56Qcexv96M2Pue FSJbzhGYlPU3H/+TkxZzT1+stcDpToCQBt7EGadw77jmBoiiaFWHnAAqC+uwQblIGh uZU13S43IODjNCg4Z3kJISCdtZQjDAGslK1NBgILJz8QyhlDCR507mg+72KoTmYwvS K3u2j2GJ7Q6bq8krMdkfUCVUsdfZkDFD2ufw4zqaL3Ake1bU2H0t0Alt9oId9vSH3p ngiFm8sRTQhkXT7KT5VcFz1Wt7g7cKBgPTSZAMqVZvQ//URIybq52aCj5PehlZblsu VipJ0YiuLYDmQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Maciej=20=C5=BBenczykowski?= , Brooke Basile , "Bryan O'Donoghue" , Felipe Balbi , Greg Kroah-Hartman , Lorenzo Colitti , Sasha Levin , linux-usb@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 12/74] usb: gadget: u_ether: fix a potential null pointer dereference Date: Thu, 9 Sep 2021 07:56:24 -0400 Message-Id: <20210909115726.149004-12-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210909115726.149004-1-sashal@kernel.org> References: <20210909115726.149004-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore 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