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=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D8CC5C433DB for ; Mon, 25 Jan 2021 13:05:43 +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 79BDD22525 for ; Mon, 25 Jan 2021 13:05:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 79BDD22525 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=Kig0blY4drzJNdwOIpyVMFdEv3tOHebMgXpa7wqEXLE=; b=UTHXN2Y7bKokJAz8sFlmRsjZj zMjsBciKwzDbiJtanrISuh2lJeSzCs8EaXjOWPBXmY/so7nCHDxtPGm8mJEbu2AVPrePSBeTrv+bK rHBVOmxzMToGGHGhkTwb2e+xlcV6BXknaOOGemKw7Gd0oktcflag5KQeXwyMTs77s9ktpHJZGmGqy 2bk0obkg154mVQlrbYXGT/+wiaf4Ehuzue4oR7BRVPx08dG1PREmDYo8CWFd+qryGqpZumjVwCOTq 2aQacuzWgvK51eLq3iOlIhmD43HhPrisCqYpeFOWw+g78oZr8WyeuI5ifqsY/v3GpsDbrzjf8Vl1m oZxYSQ1QA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l41Vg-0003hf-Do; Mon, 25 Jan 2021 13:02:24 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l41Vd-0003gL-9d for linux-arm-kernel@lists.infradead.org; Mon, 25 Jan 2021 13:02:22 +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 9A65411FB; Mon, 25 Jan 2021 05:02:18 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.45.22]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1EA8B3F66E; Mon, 25 Jan 2021 05:02:15 -0800 (PST) Date: Mon, 25 Jan 2021 13:02:04 +0000 From: Mark Rutland To: Vincenzo Frascino Subject: Re: [PATCH v4 1/3] arm64: Improve kernel address detection of __is_lm_address() Message-ID: <20210125130204.GA4565@C02TD0UTHF1T.local> References: <20210122155642.23187-1-vincenzo.frascino@arm.com> <20210122155642.23187-2-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210122155642.23187-2-vincenzo.frascino@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210125_080221_381330_4D0F03AC X-CRM114-Status: GOOD ( 21.54 ) 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: "Paul E . McKenney" , Andrey Konovalov , Naresh Kamboju , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Leon Romanovsky , Alexander Potapenko , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Andrey Ryabinin , Will Deacon , Dmitry Vyukov 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 Hi Vincenzo, 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. 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. For this patch: Acked-by: Mark Rutland Thanks, Mark. > --- > arch/arm64/include/asm/memory.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index 18fce223b67b..99d7e1494aaa 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -247,9 +247,11 @@ static inline const void *__tag_set(const void *addr, u8 tag) > > > /* > - * The linear kernel range starts at the bottom of the virtual address space. > + * Check whether an arbitrary address is within the linear map, which > + * lives in the [PAGE_OFFSET, PAGE_END) interval at the bottom of the > + * kernel's TTBR1 address range. > */ > -#define __is_lm_address(addr) (((u64)(addr) & ~PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET)) > +#define __is_lm_address(addr) (((u64)(addr) ^ PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET)) > > #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET) > #define __kimg_to_phys(addr) ((addr) - kimage_voffset) > -- > 2.30.0 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel