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 8B048C433F5 for ; Tue, 26 Oct 2021 00:29:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65B3561039 for ; Tue, 26 Oct 2021 00:29:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235350AbhJZAbj (ORCPT ); Mon, 25 Oct 2021 20:31:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235092AbhJZAbi (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 B94B8C061767 for ; Mon, 25 Oct 2021 17:29:15 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id np13so9550830pjb.4 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=qkaMzC9RtjzLrswor29HwJYEgAQa/4s1MjtRfE/A+9DT57b+VrWWMb6Fgg0nHxxHpZ D6LVR+ZRQJC/Re+a1DpEzW4Z2VdWhUM3u3fKEoosbVHwJCXuB8bw7TxLFkXnzClRuf5D Hv+vanBtgRpoJdKBbrbFBtjXWJThkdcL4kexCPtN0kUAyfGDGjh6fnMS3jgJqAQx9uB1 N58nd21wFHuJHB1bp+FnKDWMfGSBV64eVNNrQqqlecuDyyNbVa3uOeHWMFpzibSOxIFj j5wK1GirUbvGei+/oU3lP76XAPJI+27f1v3YUYdgNXDhVdhlDwZDC07d0fmLPKYOQfMQ Tffg== X-Gm-Message-State: AOAM531JKtFL4IBklLPeq4i2LV65w328bIWG4lhCorIMHLbatTaxmHD9 HLC0T2qu1vZ8Izf/e+ZolfvTxw== 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-arm-msm@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 >