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=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 DD4DBC433E1 for ; Wed, 10 Jun 2020 11:36:40 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id AF3142074B for ; Wed, 10 Jun 2020 11:36:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Z5svyJb5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF3142074B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=SamiJmVjg0S/PfrvdLYSfo33HkK8/D/dEHIfmnoW6eU=; b=Z5svyJb59GpEZA kqtGFznsh/jE47aBKZMmDGXjJxXLBN2UV4LLwhMD+dycJEhF+pNpTVEVraHWfYneqzkTjH/mtJDpe 4kIkbl13AbqPog4ioePwG0JEupPZy1S7vrJgRFVKrIHyKFa03LrjtbPX2ATFqYKk06E6Tj+VRh0lY yamVUEPUeVUCmdd7Ta7p8EvmcXimW4Db+8fihR5R3YFp0e+HPIG9oGHkeGR5Uj4rWPjOfpeD1NfX3 ycUFu4l2qk3vzkgJ2RFIyprHJkTvz+QoNSeE3wGyRkqs584/kKqN+PDo5UnxGOW1jiwaEynrW3ZQd zGMkw+cIg5YmZZVIQEDQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jiz21-0002Dj-Qi; Wed, 10 Jun 2020 11:36:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jiz1y-0002Ck-VG for linux-arm-kernel@lists.infradead.org; Wed, 10 Jun 2020 11:36:32 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6E0CB1FB; Wed, 10 Jun 2020 04:36:30 -0700 (PDT) Received: from gaia (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4303B3F66F; Wed, 10 Jun 2020 04:36:29 -0700 (PDT) Date: Wed, 10 Jun 2020 12:36:27 +0100 From: Catalin Marinas To: Shyam Thombre Subject: Re: [PATCH] arm64: mm: reset address tag set by kasan sw tagging Message-ID: <20200610113626.GI26099@gaia> References: <1591787384-5823-1-git-send-email-sthombre@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1591787384-5823-1-git-send-email-sthombre@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200610_043631_048699_9D96BC82 X-CRM114-Status: GOOD ( 15.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, sashal@kernel.org, anshuman.khandual@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, ard.biesheuvel@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jun 10, 2020 at 04:39:44PM +0530, Shyam Thombre wrote: > KASAN sw tagging sets a random tag of 8 bits in the top byte of the pointer > returned by the memory allocating functions. So for the functions unaware > of this change, the top 8 bits of the address must be reset which is done > by the function arch_kasan_reset_tag(). > > Signed-off-by: Shyam Thombre > --- > arch/arm64/mm/mmu.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index e7fbc62..eae7655 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -723,6 +723,7 @@ int kern_addr_valid(unsigned long addr) > pmd_t *pmdp, pmd; > pte_t *ptep, pte; > > + addr = arch_kasan_reset_tag(addr); > if ((((long)addr) >> VA_BITS) != -1UL) > return 0; It would be interesting to know what fails without this patch. The only user seems to be read_kcore() and, at a quick look, I don't see how it can generate tagged addresses. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel