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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 0A15BC33C8C for ; Mon, 6 Jan 2020 12:35:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8CEB2075A for ; Mon, 6 Jan 2020 12:35:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="BXwsf8wO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726383AbgAFMfV (ORCPT ); Mon, 6 Jan 2020 07:35:21 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:35951 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbgAFMfU (ORCPT ); Mon, 6 Jan 2020 07:35:20 -0500 Received: by mail-wr1-f67.google.com with SMTP id z3so49438858wru.3 for ; Mon, 06 Jan 2020 04:35:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=etHpp/b+tlLKLxjZ6TvTwVRA6Mmf6McMbwfMAQQfH4k=; b=BXwsf8wOueR/7Su482SHlTV1NZOq9Sek0uktcbPx49LyYUqGYpdX1/KKBGw4c1qhOP 3VeMM6AJ295vWqtr1HogZQL2jggx/d7H9l8aTCGvsp8NO5J/KlVynSX7f+KmAcTjEnh8 ATDQnjZWp2xFqMUBCl1ZbIAeKap/QiobXrF3B+Jx8fgjg3Ccw9Nk+1ra6iBGNbeVGKy9 lZv4pqSa3IJOh3G++W23H4qvyeQL0ZJ8py2UFrWPHHrCllgLTkG8lcC95LD71Nh52b0A 1rQsgNiCVL5VdStupvzTG9JiWOnObcDVFW1sWWWdg6TjTs1dk4Gfpmxp4UqCABomegcq i83A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=etHpp/b+tlLKLxjZ6TvTwVRA6Mmf6McMbwfMAQQfH4k=; b=VqUBHuNcWRuIRJluNSoZxk3rb7cfSgDPRr6WdvYyGa4/FV/AJ18pQuE9jHKeaH59O1 hawfC5vfbdMhS5FSCT0m2GAFB7N/sd9ZM8q1OrPkNYCazenX6ShfG/h2fwypruZE9lpR 4jX8EP0/RPF693M4Kv3s1h6Q0mkxB2L2vnaV0x1+xm/2U9nHxQCjVYoGDU0l2YLj0fU7 AX1UHou3f2jf0EnJUC5RHpAs+HmmpUcUeZ3zO85ChZ2dn3nJwYFaI4wiir9lfuocXb+T xxaKiDAT3TDbTeojZcTyJeO3rnc8QLcemNQzc/6HaE47LnRK06t4VAB1ERIG/rN4loI5 UtnQ== X-Gm-Message-State: APjAAAWdZtGMP5essZFY1qLv5dO4z1IItFMmXQShp0G8Qr+iHbobFPOv iMzymWENtSO21E3wYoi972xCYkKQsj0= X-Google-Smtp-Source: APXvYqy3oBNdsjFPXDVHPqhQuVUEc+K3UjrdOr8x429sFlMq1oz4I+8J9YqRlNLlkhJ3y728gc9Z5Q== X-Received: by 2002:a5d:4045:: with SMTP id w5mr96791354wrp.59.1578314118603; Mon, 06 Jan 2020 04:35:18 -0800 (PST) Received: from [192.168.86.34] (cpc89974-aztw32-2-0-cust43.18-1.cable.virginm.net. [86.30.250.44]) by smtp.googlemail.com with ESMTPSA id w22sm21853573wmk.34.2020.01.06.04.35.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 Jan 2020 04:35:17 -0800 (PST) Subject: Re: [PATCH] nvmem: core: Fix a potential use after free To: Xu Wang Cc: linux-kernel@vger.kernel.org References: <1577438434-9945-1-git-send-email-vulab@iscas.ac.cn> From: Srinivas Kandagatla Message-ID: Date: Mon, 6 Jan 2020 12:35:17 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1577438434-9945-1-git-send-email-vulab@iscas.ac.cn> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks for the patch. On 27/12/2019 09:20, Xu Wang wrote: > Free the nvmem structure only after we are done using it. > This patch just moves the put_device() down a bit to avoid the > use after free. Could you explain the issue bit more here on what exactly could go wrong with the exiting order? may be the stack trace of the use-after-free case? Or steps to reproduce the issue? nvmem device is protected with kref. --srini > > Signed-off-by: Xu Wang > --- > drivers/nvmem/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c > index 9f1ee9c..7051d34 100644 > --- a/drivers/nvmem/core.c > +++ b/drivers/nvmem/core.c > @@ -535,8 +535,8 @@ static struct nvmem_device *__nvmem_device_get(void *data, > > static void __nvmem_device_put(struct nvmem_device *nvmem) > { > - put_device(&nvmem->dev); > module_put(nvmem->owner); > + put_device(&nvmem->dev); > kref_put(&nvmem->refcnt, nvmem_device_release); > } > >