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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0FA8C433EF for ; Thu, 20 Jan 2022 18:14:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237750AbiATSOM (ORCPT ); Thu, 20 Jan 2022 13:14:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232699AbiATSOK (ORCPT ); Thu, 20 Jan 2022 13:14:10 -0500 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EACDC061574 for ; Thu, 20 Jan 2022 10:14:10 -0800 (PST) Received: by mail-pf1-x42b.google.com with SMTP id u130so2041581pfc.2 for ; Thu, 20 Jan 2022 10:14:10 -0800 (PST) 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=sOK8Ok1ZQTzg6dPQtib4q7TePacA51amgY3BF4r2O1o=; b=Y4sbbhTqE7AAD2RzVTue6vc5Z6vuYgXfQ1sPlZPXPMTjobl3QwI28uzhtYvZlf/wAG vZKG6DebmDBeofQ+VuovAIymHF6dDrzvPWOimZluxaJD74HTS2r42u5lFcCvQMwrcHhY SbtxPMjtWY/8+S5xKGp+Socd73ZR4wOZAYbW0= 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=sOK8Ok1ZQTzg6dPQtib4q7TePacA51amgY3BF4r2O1o=; b=mGF3Iym3tZ53anG8PAbxSdI0FF9EPcYDJonB/LLmtoNzBBY7ucZDph1w8Q55+osIC1 arGgusqYoY5rm2q2Zo5h1XehwCG4o3d7qfe0jSdqYlU9SKzO02lXzCYeVOTwf8dV0mtV EETx4/DBFP2ywmw3uHdeHl36Le/JCEOWxhbE63rLq1uMH5xfjcYjHf4+MoxxFwQnw0Pf ajs4LJBKn44hWF0Qx1sRHZ1JH3dWGY7wWyVj38VzYXAxL2LxTnYJ5g84oy0Z3kM/i+Lf AQcdxWJBvFtncXkQEnWYXpOFS+npouJPGozeb6aJ2caCdMGt/x4SNNeiqnjNLgZqTEzW SZqA== X-Gm-Message-State: AOAM533hLgxKDokCy/cppdAzX/qLUO6feGrPx+OuR2F6nAhhZnT4xZ1k 9DJpuuMHvN59Kq4QCfF1O8+h+w== X-Google-Smtp-Source: ABdhPJwmT5hMY53u7eLodFYspiBUE96qUrOhvQcgxNnwWIXi+G/UmDp2ceTPJ825tLGKRM3b9yk4Yg== X-Received: by 2002:a63:81c8:: with SMTP id t191mr1059324pgd.135.1642702449716; Thu, 20 Jan 2022 10:14:09 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id z17sm4386180pfe.10.2022.01.20.10.14.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Jan 2022 10:14:09 -0800 (PST) Date: Thu, 20 Jan 2022 10:14:08 -0800 From: Kees Cook To: Jiasheng Jiang Cc: gregkh@linuxfoundation.org, dan.carpenter@oracle.com, arnd@arndb.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] lkdtm/bugs: Check for the NULL pointer after calling kmalloc Message-ID: <202201201013.0079B1D@keescook> References: <20220120092936.1874264-1-jiasheng@iscas.ac.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220120092936.1874264-1-jiasheng@iscas.ac.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 20, 2022 at 05:29:36PM +0800, Jiasheng Jiang wrote: > As the possible failure of the kmalloc(), the not_checked and checked > could be NULL pointer. > Therefore, it should be better to check it in order to avoid the > dereference of the NULL pointer. > Also, we need to kfree the 'not_checked' and 'checked' to avoid > the memory leak if fails. > And since it is just a test, it may directly return without error > number. > > Fixes: ae2e1aad3e48 ("drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks") > Signed-off-by: Jiasheng Jiang > --- > Changelog > > v1 -> v2 > > * Change 1. Add the kfree if fails. > > v2 -> v3 > > * Change 1. Add pr_err if fails. > > v3 -> v4 > > * Change 1. Revert to v2 that remove the pr_err. > --- > drivers/misc/lkdtm/bugs.c | 5 +++++ > 1 file changed, 5 insertions(+) Acked-by: Kees Cook > > diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c > index 4282b625200f..072e3b742edf 100644 > --- a/drivers/misc/lkdtm/bugs.c > +++ b/drivers/misc/lkdtm/bugs.c > @@ -248,6 +248,11 @@ void lkdtm_ARRAY_BOUNDS(void) > > not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL); > checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL); > + if (!not_checked || !checked) { > + kfree(not_checked); > + kfree(checked); > + return; > + } > > pr_info("Array access within bounds ...\n"); > /* For both, touch all bytes in the actual member size. */ > -- > 2.25.1 > -- Kees Cook