From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f72.google.com (mail-pl0-f72.google.com [209.85.160.72]) by kanga.kvack.org (Postfix) with ESMTP id 72B486B0007 for ; Tue, 6 Mar 2018 12:05:06 -0500 (EST) Received: by mail-pl0-f72.google.com with SMTP id t12-v6so10099685plo.9 for ; Tue, 06 Mar 2018 09:05:06 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id d19sor4764137pfm.66.2018.03.06.09.05.05 for (Google Transport Security); Tue, 06 Mar 2018 09:05:05 -0800 (PST) Subject: Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var References: <20180223144807.1180-1-igor.stoppa@huawei.com> <20180223144807.1180-7-igor.stoppa@huawei.com> From: J Freyensee Message-ID: <1120e8fd-2f48-5b1f-7072-9bd8e2b82fbf@gmail.com> Date: Tue, 6 Mar 2018 09:05:00 -0800 MIME-Version: 1.0 In-Reply-To: <20180223144807.1180-7-igor.stoppa@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Igor Stoppa , david@fromorbit.com, willy@infradead.org, keescook@chromium.org, mhocko@kernel.org Cc: labbott@redhat.com, linux-security-module@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com > > +#ifdef CONFIG_PROTECTABLE_MEMORY > +void lkdtm_WRITE_RO_PMALLOC(void) > +{ > + struct gen_pool *pool; > + int *i; > + > + pool = pmalloc_create_pool("pool", 0); > + if (unlikely(!pool)) { > + pr_info("Failed preparing pool for pmalloc test."); > + return; > + } > + > + i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL); > + if (unlikely(!i)) { > + pr_info("Failed allocating memory for pmalloc test."); > + pmalloc_destroy_pool(pool); > + return; > + } > + > + *i = INT_MAX; > + pmalloc_protect_pool(pool); > + > + pr_info("attempting bad pmalloc write at %p\n", i); > + *i = 0; Seems harmless, but I don't get why *i local variable needs to be set to 0 at the end of this function. Otherwise, Reviewed-by: Jay Freyensee -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org