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=-14.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 36F5BC49EA2 for ; Tue, 15 Jun 2021 13:31:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C75761481 for ; Tue, 15 Jun 2021 13:31:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231620AbhFONde (ORCPT ); Tue, 15 Jun 2021 09:33:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231740AbhFONdT (ORCPT ); Tue, 15 Jun 2021 09:33:19 -0400 Received: from mail-lf1-x129.google.com (mail-lf1-x129.google.com [IPv6:2a00:1450:4864:20::129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE258C0611C0; Tue, 15 Jun 2021 06:31:14 -0700 (PDT) Received: by mail-lf1-x129.google.com with SMTP id r198so27033832lff.11; Tue, 15 Jun 2021 06:31:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=X7QyFpMRaIz1rkNDj3CFhI3o4WQb4st3n6J/P7lJ3Sg=; b=prwqd50vb1jED1ChJkbgOKTYUSRG3d8znIigmJ36m6usDi8dy6y0j1aw6lRsUEIzlC 2zzvTmV6pHr7AMRGDyYFgcnUWdRHhv17ZTGzBhaKN0agg+wsbRd7QRyxocsZPT1vlHP8 2vxIWP+7m4fBmMWttxahSsU97OhQleqE07OFEqpdAFK3Jup/2bJxNM5qtLFSeKF+jiIH IFdcX80N81WJ1e9q7o2pgOPP8Ui0cIq/hsTCzyaNQdHcjAPvbU8Arg3FNEElWgIbbUtE zqcv00r566ut5Veq4+x1Ool2fN7WE2A2agNkbAkPnngPjDxa9kGF6XgQ+B4Ye1Sip8iV U8oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=X7QyFpMRaIz1rkNDj3CFhI3o4WQb4st3n6J/P7lJ3Sg=; b=tAGF4vsIIAVphKX3n2ri6o7cLevZ1vZxV4aNgByQfIXbrGHwyrZ48d0Hgq6uOMJKUj wIX1rTqLZrxHxp/7wsXeKJf4MeIJgu7q9Xt4oj+CcG12vAEd/rfjcBFrGzBLog5TZcpZ xPCKN5vS2/jRn2UP5TFW+f8vnt08UyKl71H4Ij9B3o+v7QN37XhuL+x/d20PI96VKSEL ZvvdsX55GX7aaQphKQAAdNvxqEdg9iMgMP/AephbFAILdoMUZ/VRLhZ5lQuSaA5cyEXy gYen85OSA1vJlFzzfdi467snUyz0RNwQKtMwHPjquS7KoKbSqGErHKlXeRce6ymIKKTZ aXkg== X-Gm-Message-State: AOAM533/MnHwsP+FINhjLhwqbG57jePyG8lIO8Lgmoa4lRmZJGDQ+25K kzU/C1e5mCDJPN6gmXAlPtE= X-Google-Smtp-Source: ABdhPJw94FAsLDrGBTvWO123dKNb9daIY+CCi2QI8rsnF4OSdz/E2yANZv47gE84FfW4plSn8qOD2Q== X-Received: by 2002:a05:6512:944:: with SMTP id u4mr15978195lft.30.1623763873226; Tue, 15 Jun 2021 06:31:13 -0700 (PDT) Received: from localhost.localdomain ([94.103.229.24]) by smtp.gmail.com with ESMTPSA id z8sm1806752lfg.243.2021.06.15.06.31.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jun 2021 06:31:12 -0700 (PDT) Date: Tue, 15 Jun 2021 16:31:08 +0300 From: Pavel Skripkin To: Dongliang Mu Cc: Steve Glendinning , "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel Subject: Re: [PATCH] net: usb: fix possible use-after-free in smsc75xx_bind Message-ID: <20210615163108.4e17e119@gmail.com> In-Reply-To: References: <20210614153712.2172662-1-mudongliangabcd@gmail.com> <20210614190045.5b4c92e6@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Jun 2021 07:01:13 +0800 Dongliang Mu wrote: > On Tue, Jun 15, 2021 at 12:00 AM Pavel Skripkin > wrote: > > > > On Mon, 14 Jun 2021 23:37:12 +0800 > > Dongliang Mu wrote: > > > > > The commit 46a8b29c6306 ("net: usb: fix memory leak in > > > smsc75xx_bind") fails to clean up the work scheduled in > > > smsc75xx_reset-> smsc75xx_set_multicast, which leads to > > > use-after-free if the work is scheduled to start after the > > > deallocation. In addition, this patch also removes one dangling > > > pointer - dev->data[0]. > > > > > > This patch calls cancel_work_sync to cancel the schedule work and > > > set the dangling pointer to NULL. > > > > > > Fixes: 46a8b29c6306 ("net: usb: fix memory leak in smsc75xx_bind") > > > Signed-off-by: Dongliang Mu > > > --- > > > drivers/net/usb/smsc75xx.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/net/usb/smsc75xx.c > > > b/drivers/net/usb/smsc75xx.c index b286993da67c..f81740fcc8d5 > > > 100644 --- a/drivers/net/usb/smsc75xx.c > > > +++ b/drivers/net/usb/smsc75xx.c > > > @@ -1504,7 +1504,10 @@ static int smsc75xx_bind(struct usbnet > > > *dev, struct usb_interface *intf) return 0; > > > > > > err: > > > + cancel_work_sync(&pdata->set_multicast); > > > kfree(pdata); > > > + pdata = NULL; > > > + dev->data[0] = 0; > > > return ret; > > > } > > > > > > > Hi, Dongliang! > > > > Just my thougth about this patch: > > > > INIT_WORK(&pdata->set_multicast, smsc75xx_deferred_multicast_write); > > does not queue anything, it just initalizes list structure and > > assigns callback function. The actual work sheduling happens in > > smsc75xx_set_multicast() which is smsc75xx_netdev_ops member. > > > > Yes, you are right. However, as written in the commit message, > smsc75xx_set_multicast will be called by smsc75xx_reset [1]. > > If smsc75xx_set_multicast is called before any check failure occurs, > this work(set_multicast) will be queued into the global list with > > schedule_work(&pdata->set_multicast); [2] Ah, I missed it, sorry :) Maybe, small optimization for error handling path like: cancel_work: cancel_work_sync(&pdata->set_multicast); dev->data[0] = 0; free_pdata: kfree(pdata); return ret; is suitbale here. > > At last, if the pdata or dev->data[0] is freed before the > set_multicast really executes, it may lead to a UAF. Is this correct? > > BTW, even if the above is true, I don't know if I call the API > ``cancel_work_sync(&pdata->set_multicast)'' properly if the > schedule_work is not called. > Yeah, it will be ok. > [1] > https://elixir.bootlin.com/linux/latest/source/drivers/net/usb/smsc75xx.c#L1322 > > [2] > https://elixir.bootlin.com/linux/latest/source/drivers/net/usb/smsc75xx.c#L583 > > > In case of any error in smsc75xx_bind() the device registration > > fails and smsc75xx_netdev_ops won't be registered, so, i guess, > > there is no chance of UAF. > > > > > > Am I missing something? :) > > > > > > > > With regards, > > Pavel Skripkin With regards, Pavel Skripkin