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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 DA93CC71155 for ; Wed, 2 Dec 2020 18:53:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CDF272173E for ; Wed, 2 Dec 2020 18:53:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDF272173E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2708F6B0036; Wed, 2 Dec 2020 13:53:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F9BB6B005C; Wed, 2 Dec 2020 13:53:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0C3116B005D; Wed, 2 Dec 2020 13:53:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0101.hostedemail.com [216.40.44.101]) by kanga.kvack.org (Postfix) with ESMTP id E683C6B0036 for ; Wed, 2 Dec 2020 13:53:41 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id B3E088249980 for ; Wed, 2 Dec 2020 18:53:41 +0000 (UTC) X-FDA: 77549241042.03.knee89_1d16890273b5 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin03.hostedemail.com (Postfix) with ESMTP id 710EE28A4E8 for ; Wed, 2 Dec 2020 18:53:41 +0000 (UTC) X-HE-Tag: knee89_1d16890273b5 X-Filterd-Recvd-Size: 2761 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Wed, 2 Dec 2020 18:53:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=x7k2lFyLJB5bfb9fPEzXzFBJq+3Mj4qBHsnAWTloKu4=; b=Dju+loNs6iUz8v0bfjzjUmbQ4a UL6t4b3LCv0bXx3LCcybXbyCs+QdLkl+Vsa+/HnihsiPhPpIW5Wczaukyozfn9pZIcgi08BwDDLwb gwS9p5K1ElOb22EzeWxLMWUGrzkwqkP8/k4XQSe/ZJkld40dVsuz5Cidy1dEHk3JvWQwV502ra8iw 6s5uep//lxA8cphkUuDZK3HfjX135eCF96j1aLBNupUEiJXv0q6LViNsoBcvf0f7Ghe0wVo2XSAkS RCWi2QGeu+8qB+WIY02RsAQe+EL487YBClM6XRRMEVRPckmQHGFoOt9EzxZILGo6yxPsft7VKRJLw 41k6blcQ==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkXFu-0004eS-PH; Wed, 02 Dec 2020 18:53:34 +0000 Date: Wed, 2 Dec 2020 18:53:34 +0000 From: Matthew Wilcox To: Topi Miettinen Cc: linux-hardening@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Jann Horn , Kees Cook , Linux API , Mike Rapoport Subject: Re: [PATCH] mm/vmalloc: randomize vmalloc() allocations Message-ID: <20201202185334.GG11935@casper.infradead.org> References: <20201201214547.9721-1-toiwoton@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201214547.9721-1-toiwoton@gmail.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Dec 01, 2020 at 11:45:47PM +0200, Topi Miettinen wrote: > + /* Randomize allocation */ > + if (randomize_vmalloc) { > + voffset = get_random_long() & (roundup_pow_of_two(vend - vstart) - 1); > + voffset = PAGE_ALIGN(voffset); > + if (voffset + size > vend - vstart) > + voffset = vend - vstart - size; > + } else > + voffset = 0; > + > /* > * If an allocation fails, the "vend" address is > * returned. Therefore trigger the overflow path. > */ > - addr = __alloc_vmap_area(size, align, vstart, vend); > + addr = __alloc_vmap_area(size, align, vstart + voffset, vend); > spin_unlock(&free_vmap_area_lock); What if there isn't any free address space between vstart+voffset and vend, but there is free address space between vstart and voffset? Seems like we should add: addr = __alloc_vmap_area(size, align, vstart + voffset, vend); + if (!addr) + addr = __alloc_vmap_area(size, align, vstart, vend); spin_unlock(&free_vmap_area_lock);