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=-17.5 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,USER_AGENT_SANE_1 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 44897C433ED for ; Thu, 22 Apr 2021 04:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1EA9461222 for ; Thu, 22 Apr 2021 04:26:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229557AbhDVE0r (ORCPT ); Thu, 22 Apr 2021 00:26:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:51720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbhDVE0r (ORCPT ); Thu, 22 Apr 2021 00:26:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E640160698; Thu, 22 Apr 2021 04:26:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619065573; bh=M9WEz3stHuTUGOfvNJEUfe/rwnc74K79vU61YmvGy0Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Q+rDhgjON4c6Nb4n2eD5hZDXOs2ZmfIz1ofKdwD4pMNcbPm7z5kZj5jSJX0iwsk8C HeFzHgtv96tefEI7bFgKNMsNTNzId6f8MlUtXLpZ0anZc3UMSfzEfFgR5mWBGiLh4X mOckdniayURhzzP2A41yXkTJEDxeWLffHa1xxB147y5g5vkl9uy7PX1lKAFB4ODiWP /hJDOArWoWIkuK6CsSl6ff0WGhw5XpXYP7f0hXcBvuru8StEt8Mws15v7654fiCZkK YJiD/u5d4+r7NtPD7MnnLN0RsQCZW1PfRMs2EpPYqQ5I5HPSKFHn7ZgcAV4OQVZW9f p6ag06Tz8ERkA== Date: Thu, 22 Apr 2021 09:56:04 +0530 From: Manivannan Sadhasivam To: Bjorn Andersson Cc: "David S. Miller" , Jakub Kicinski , linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: qrtr: Avoid potential use after free in MHI send Message-ID: <20210422042604.GB14470@work> References: <20210421174007.2954194-1-bjorn.andersson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210421174007.2954194-1-bjorn.andersson@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Wed, Apr 21, 2021 at 10:40:07AM -0700, Bjorn Andersson wrote: > It is possible that the MHI ul_callback will be invoked immediately > following the queueing of the skb for transmission, leading to the > callback decrementing the refcount of the associated sk and freeing the > skb. > > As such the dereference of skb and the increment of the sk refcount must > happen before the skb is queued, to avoid the skb to be used after free > and potentially the sk to drop its last refcount.. > > Fixes: 6e728f321393 ("net: qrtr: Add MHI transport layer") > Signed-off-by: Bjorn Andersson Reviewed-by: Manivannan Sadhasivam Thanks, Mani > --- > net/qrtr/mhi.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c > index 2bf2b1943e61..fa611678af05 100644 > --- a/net/qrtr/mhi.c > +++ b/net/qrtr/mhi.c > @@ -50,6 +50,9 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) > struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep); > int rc; > > + if (skb->sk) > + sock_hold(skb->sk); > + > rc = skb_linearize(skb); > if (rc) > goto free_skb; > @@ -59,12 +62,11 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb) > if (rc) > goto free_skb; > > - if (skb->sk) > - sock_hold(skb->sk); > - > return rc; > > free_skb: > + if (skb->sk) > + sock_put(skb->sk); > kfree_skb(skb); > > return rc; > -- > 2.29.2 >