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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,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 32D4FC433DB for ; Mon, 25 Jan 2021 15:01:12 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 D3151225A9 for ; Mon, 25 Jan 2021 15:01:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D3151225A9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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=W5nr5uWk3ZHE7MewTf9Zkl+ZsDxgUhSbkIW0DVelhCA=; b=StrTpOSjA+UJng0UXpODX/lD0 Ym6MzC5SjkH9ntgZoJEqjzVWOBc7byd++dbKVmEC1c/aIzDQZ1hbZh6YKGEIvwm7yI1BmAoc86N27 d0akSaRnZWspAgtBw3t7zhOIJVYFsvfFYZHGFR/XfaVQeoDKEUpNlP07GMsLDuycrvA5y8FKUeNJW EmczgqFHuuanIFpJw8nP9kFP0BZxJfAbd+VjFQyr0RnBy28VpzQPxwKj8a9xMe8eeJNxuGmpiy1Uq ZgwJnSLNsHrqjuYSxteNJSRcJfriFZiilT/aJsQC7BdRb/ZqpcDdquCIQS/Z9s2G0Bmh0i9cEOmp2 Z2OOKtttA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l43Kq-0007IH-0i; Mon, 25 Jan 2021 14:59:20 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l43Kn-0007Hs-Jn for linux-arm-kernel@lists.infradead.org; Mon, 25 Jan 2021 14:59:18 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id E1BA622ADF; Mon, 25 Jan 2021 14:59:14 +0000 (UTC) Date: Mon, 25 Jan 2021 14:59:12 +0000 From: Catalin Marinas To: Vincenzo Frascino Subject: Re: [PATCH v4 1/3] arm64: Improve kernel address detection of __is_lm_address() Message-ID: <20210125145911.GG25360@gaia> References: <20210122155642.23187-1-vincenzo.frascino@arm.com> <20210122155642.23187-2-vincenzo.frascino@arm.com> <20210125130204.GA4565@C02TD0UTHF1T.local> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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-20210125_095917_783796_084A45BC X-CRM114-Status: GOOD ( 24.55 ) 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 , "Paul E . McKenney" , Andrey Konovalov , Naresh Kamboju , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Leon Romanovsky , Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , Will Deacon , 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+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jan 25, 2021 at 02:36:34PM +0000, Vincenzo Frascino wrote: > On 1/25/21 1:02 PM, Mark Rutland wrote: > > On Fri, Jan 22, 2021 at 03:56:40PM +0000, Vincenzo Frascino wrote: > >> Currently, the __is_lm_address() check just masks out the top 12 bits > >> of the address, but if they are 0, it still yields a true result. > >> This has as a side effect that virt_addr_valid() returns true even for > >> invalid virtual addresses (e.g. 0x0). > >> > >> Improve the detection checking that it's actually a kernel address > >> starting at PAGE_OFFSET. > >> > >> Cc: Catalin Marinas > >> Cc: Will Deacon > >> Suggested-by: Catalin Marinas > >> Reviewed-by: Catalin Marinas > >> Signed-off-by: Vincenzo Frascino > > > > Looking around, it seems that there are some existing uses of > > virt_addr_valid() that expect it to reject addresses outside of the > > TTBR1 range. For example, check_mem_type() in drivers/tee/optee/call.c. > > > > Given that, I think we need something that's easy to backport to stable. > > > > I agree, I started looking at it this morning and I found cases even in the main > allocators (slub and page_alloc) either then the one you mentioned. > > > This patch itself looks fine, but it's not going to backport very far, > > so I suspect we might need to write a preparatory patch that adds an > > explicit range check to virt_addr_valid() which can be trivially > > backported. > > > > I checked the old releases and I agree this is not back-portable as it stands. > I propose therefore to add a preparatory patch with the check below: > > #define __is_ttrb1_address(addr) ((u64)(addr) >= PAGE_OFFSET && \ > (u64)(addr) < PAGE_END) > > If it works for you I am happy to take care of it and post a new version of my > patches. I'm not entirely sure we need a preparatory patch. IIUC (it needs checking), virt_addr_valid() was fine until 5.4, broken by commit 14c127c957c1 ("arm64: mm: Flip kernel VA space"). Will addressed the flip case in 68dd8ef32162 ("arm64: memory: Fix virt_addr_valid() using __is_lm_address()") but this broke the