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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21EA5C4332F for ; Tue, 26 Oct 2021 00:29:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0233A61073 for ; Tue, 26 Oct 2021 00:29:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235424AbhJZAbn (ORCPT ); Mon, 25 Oct 2021 20:31:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235233AbhJZAbi (ORCPT ); Mon, 25 Oct 2021 20:31:38 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0206C061348 for ; Mon, 25 Oct 2021 17:29:15 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id fv3so3555546pjb.3 for ; Mon, 25 Oct 2021 17:29:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=kzA4EpTi7z77s3KOJZLkB0akISy0U4YTxQuvmocFUgU=; b=OTupR3eFronvQywS7qKloj2ZVgcgrUGU/A/27Yw2/EU5C9UbHbGZucQzrCf2ptOXdz JExxVRam2bJbStJtkTgcgv3YR0cZYtk9mNJ27PLJ5JQtLcoUt+aNeh0/qa03koQNa6Nl V4YDAax5mWX2epn6cq3yjiQTCAl/s/72/ZXfI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=kzA4EpTi7z77s3KOJZLkB0akISy0U4YTxQuvmocFUgU=; b=nELMMCZ1RwIywoBGFHTfz50Ag2LN7Sa+okDqenEWmSBvJdV3FCD8RnczSmlIb16FIf /C2SawRJBMay1jvHJiKNtqye7CN5KCmZcQD5Qmvq+R1TzAoZCka4JB3mVzqsGhOjs1HG q0cnZdnyOAnQ5XztLg4j7XtBd90dVf1DkRkFAwuObp0q5bm7C45OMz6i1xqpFtxSf9rJ GnDcTxox8JeZXaKaBAEUM46JhEaqNiy44FH7OBWryaakuPGtDIPVbQSv6U8jBt3NspgD 3Q6YH6KeFQFmueXCPoCWHd8o6VgKjLeHXYP4KlfJIr8WAqBk9dyQW6NMcoQHp19wdqqw yPGg== X-Gm-Message-State: AOAM532TF0tPE/P2pk/zQ0QYKwEf+fFhCVBOFx1kwWV3P9nHeVDLcq4j do9IlK5gkof+1Z+s7Su+HKixoA== X-Google-Smtp-Source: ABdhPJwYnSMKPYjmI8QhrAgLoT1GbHwUyZJLSvXqMzWfZiE7NSs2GXs7skPU1ESitnVKLZoPFaldrQ== X-Received: by 2002:a17:90a:e505:: with SMTP id t5mr14530311pjy.33.1635208155201; Mon, 25 Oct 2021 17:29:15 -0700 (PDT) Received: from localhost ([2620:15c:202:201:5822:765c:9f84:e1b3]) by smtp.gmail.com with UTF8SMTPSA id l14sm23244442pjq.13.2021.10.25.17.29.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Oct 2021 17:29:14 -0700 (PDT) Date: Mon, 25 Oct 2021 17:29:13 -0700 From: Matthias Kaehlcke To: Sujit Kautkar Cc: Andy Gross , Ohad Ben-Cohen , Stephen Boyd , Sibi Sankar , Bjorn Andersson , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org Subject: Re: [PATCH v2 1/2] rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release() Message-ID: References: <20211025233751.1777479-1-sujitka@chromium.org> <20211025163739.v2.1.Id19324ea36b4cf89faf98bf520bc6b6f01240433@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20211025163739.v2.1.Id19324ea36b4cf89faf98bf520bc6b6f01240433@changeid> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 25, 2021 at 04:37:52PM -0700, Sujit Kautkar wrote: > qcom_glink_rpdev_release() sets channel->rpdev to NULL. However, with > debug enabled kernel, qcom_glink_rpdev_release() gets delayed due to > delayed kobject release and channel gets released by that time and > triggers below kernel warning. To avoid this use-after-free, add a > condition to checks if channel was already released. > > | BUG: KASAN: use-after-free in qcom_glink_rpdev_release+0x54/0x70 > | Write of size 8 at addr ffffffaba438e8d0 by task kworker/6:1/54 > | > | CPU: 6 PID: 54 Comm: kworker/6:1 Not tainted 5.4.109-lockdep #16 > | Hardware name: Google Lazor (rev3+) with KB Backlight (DT) > | Workqueue: events kobject_delayed_cleanup > | Call trace: > | dump_backtrace+0x0/0x284 > | show_stack+0x20/0x2c > | dump_stack+0xd4/0x170 > | print_address_description+0x3c/0x4a8 > | __kasan_report+0x144/0x168 > | kasan_report+0x10/0x18 > | __asan_report_store8_noabort+0x1c/0x24 > | qcom_glink_rpdev_release+0x54/0x70 > | device_release+0x68/0x14c > | kobject_delayed_cleanup+0x158/0x2cc > | process_one_work+0x7cc/0x10a4 > | worker_thread+0x80c/0xcec > | kthread+0x2a8/0x314 > | ret_from_fork+0x10/0x18 > > Signed-off-by: Sujit Kautkar > --- > > (no changes since v1) > > drivers/rpmsg/qcom_glink_native.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c > index e1444fefdd1c0..cc3556a9385a9 100644 > --- a/drivers/rpmsg/qcom_glink_native.c > +++ b/drivers/rpmsg/qcom_glink_native.c > @@ -270,6 +270,7 @@ static void qcom_glink_channel_release(struct kref *ref) > spin_unlock_irqrestore(&channel->intent_lock, flags); > > kfree(channel->name); > + channel = NULL; This doesn't make much sense, 'channel' is a local variable, the only effect this has is that the memory of 'channel' isn't freed by the 'kfree' below. Maybe this is debug code and wasn't intended to be part of this patch? > kfree(channel); > } > > @@ -1372,8 +1373,10 @@ static void qcom_glink_rpdev_release(struct device *dev) > { > struct rpmsg_device *rpdev = to_rpmsg_device(dev); > struct glink_channel *channel = to_glink_channel(rpdev->ept); > + if (channel) { > + channel->rpdev = NULL; > + } Remove curly braces for single line branch. > > - channel->rpdev = NULL; > kfree(rpdev); > } > > -- > 2.31.0 >