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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 06764C77B61 for ; Fri, 28 Apr 2023 16:58:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=iROYzX1YItXkBumRcF/r8BV3QEmvs3oOriXMJjZdVng=; b=cc7CQjszWISyFY hjqtQHWibQx4MlaATSHaGDAyT6YAY0iq/I7/h269/fsiG3KslAGYcdo5zVBT9A4cKn+R4c7EtBDRv InmpPToSz+HWH6nECYhmqf/VKiBV2tN1UOchRkMzgE5wgE0XtbOkEjTjB05YZ8HtzCryCa1kDXQER 8oFWEsyElnInrY7iUm4/bggEJ0LrDP6doGGoSJ/ybKCsYUGYNKx8mKwXtJeRoqKqT7WlzVMtJeLMO MTmn25IrsxMwmojpnhvXtK3MSpIpS4ebEZSQLcZVe7AvrNhSR6qKULxuvi05ZglH8n7snT94LinFX 2APjrOfflYlfyDRju9Eg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1psRPR-00BHlx-0x; Fri, 28 Apr 2023 16:57:25 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1psRPO-00BHlJ-0o for linux-arm-kernel@lists.infradead.org; Fri, 28 Apr 2023 16:57:23 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 22B4A6449D; Fri, 28 Apr 2023 16:57:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F523C433EF; Fri, 28 Apr 2023 16:57:18 +0000 (UTC) Date: Fri, 28 Apr 2023 17:57:15 +0100 From: Catalin Marinas To: Peter Collingbourne Cc: andreyknvl@gmail.com, Qun-wei Lin =?utf-8?B?KOael+e+pOW0tCk=?= , Guangye Yang =?utf-8?B?KOadqOWFieS4mik=?= , linux-mm@kvack.org, Chinwen Chang =?utf-8?B?KOW8temMpuaWhyk=?= , kasan-dev@googlegroups.com, ryabinin.a.a@gmail.com, linux-arm-kernel@lists.infradead.org, vincenzo.frascino@arm.com, will@kernel.org, eugenis@google.com, stable@vger.kernel.org Subject: Re: [PATCH] arm64: Also reset KASAN tag if page is not PG_mte_tagged Message-ID: References: <20230420210945.2313627-1-pcc@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230420210945.2313627-1-pcc@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230428_095722_354060_586E52BA X-CRM114-Status: GOOD ( 17.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Apr 20, 2023 at 02:09:45PM -0700, Peter Collingbourne wrote: > Consider the following sequence of events: > > 1) A page in a PROT_READ|PROT_WRITE VMA is faulted. > 2) Page migration allocates a page with the KASAN allocator, > causing it to receive a non-match-all tag, and uses it > to replace the page faulted in 1. > 3) The program uses mprotect() to enable PROT_MTE on the page faulted in 1. > > As a result of step 3, we are left with a non-match-all tag for a page > with tags accessible to userspace, which can lead to the same kind of > tag check faults that commit e74a68468062 ("arm64: Reset KASAN tag in > copy_highpage with HW tags only") intended to fix. > > The general invariant that we have for pages in a VMA with VM_MTE_ALLOWED > is that they cannot have a non-match-all tag. As a result of step 2, the > invariant is broken. This means that the fix in the referenced commit > was incomplete and we also need to reset the tag for pages without > PG_mte_tagged. > > Fixes: e5b8d9218951 ("arm64: mte: reset the page tag in page->flags") > Cc: # 5.15 > Link: https://linux-review.googlesource.com/id/I7409cdd41acbcb215c2a7417c1e50d37b875beff > Signed-off-by: Peter Collingbourne Sorry, forgot to reply: Reviewed-by: Catalin Marinas _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel