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=-15.7 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,NICE_REPLY_A,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 3F95FC433DB for ; Fri, 22 Jan 2021 14:55:48 +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 06BD2239EE for ; Fri, 22 Jan 2021 14:55:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06BD2239EE 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:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8gpUB1O8klfS0WFAYBQMh5oBSiZPPMMPC0vHm0zGoXc=; b=Bk+3j9gCQulI43QjtIII7BN+M gUVCiePJS1fpuSNQpKUJYQcZKrY3bBCbD9DiAHBq44zJ1DWdrY5zx1Wz9fE3wwBE8MMWcaoXsyxlW nBIfoE+XeUNCL7qtlqBfxCf7axbZV/6nUM9W+Jhtixd8fMGSVJAxOaiD8gg/JR1k7zdgD3nm2jjZZ O0rb8Qk9y93CZ8OGDVftsSayC0FrJCNlNpD/OThXjK7I63YdCxbtbdEta7A7j5G82r/lgnbSHcig3 W1NIRA+c+9RqnkIomNnuyRmAYwHu720uG61LGs/SlIkLzEsOc4lPNu4oLrZOU6v91yjds7heezac+ GcjU9nJAQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2xpX-0003Ao-Jj; Fri, 22 Jan 2021 14:54:31 +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 1l2xpU-0003AI-EL for linux-arm-kernel@lists.infradead.org; Fri, 22 Jan 2021 14:54:29 +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 CE3ED11D4; Fri, 22 Jan 2021 06:54:23 -0800 (PST) Received: from [10.37.8.28] (unknown [10.37.8.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AEEBA3F66E; Fri, 22 Jan 2021 06:54:21 -0800 (PST) Subject: Re: [PATCH v3 2/2] kasan: Add explicit preconditions to kasan_report() To: Andrey Konovalov References: <20210122143748.50089-1-vincenzo.frascino@arm.com> <20210122143748.50089-3-vincenzo.frascino@arm.com> From: Vincenzo Frascino Message-ID: Date: Fri, 22 Jan 2021 14:58:12 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210122_095428_584122_55442C96 X-CRM114-Status: GOOD ( 25.11 ) 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" , Catalin Marinas , Naresh Kamboju , LKML , kasan-dev , Leon Romanovsky , Alexander Potapenko , Linux ARM , 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 On 1/22/21 2:46 PM, Andrey Konovalov wrote: > On Fri, Jan 22, 2021 at 3:38 PM Vincenzo Frascino > wrote: >> >> With the introduction of KASAN_HW_TAGS, kasan_report() dereferences >> the address passed as a parameter. > > It doesn't dereference the address, it accesses the metadata. And only > when addr_has_metadata() succeeds. > Yes, this is correct. Seems I forgot again to unstash something. Will fix it in v4. >> >> Add a comment to make sure that the preconditions to the function are >> explicitly clarified. >> >> Note: An invalid address (e.g. NULL) passed to the function when, >> KASAN_HW_TAGS is enabled, leads to a kernel panic. > > This is no longer true, right? Commit description needs to be updated. > >> >> Cc: Andrey Ryabinin >> Cc: Alexander Potapenko >> Cc: Dmitry Vyukov >> Cc: Leon Romanovsky >> Cc: Andrey Konovalov >> Signed-off-by: Vincenzo Frascino >> --- >> include/linux/kasan.h | 7 +++++++ >> mm/kasan/kasan.h | 2 +- >> 2 files changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/kasan.h b/include/linux/kasan.h >> index fe1ae73ff8b5..0aea9e2a2a01 100644 >> --- a/include/linux/kasan.h >> +++ b/include/linux/kasan.h >> @@ -333,6 +333,13 @@ static inline void *kasan_reset_tag(const void *addr) >> return (void *)arch_kasan_reset_tag(addr); >> } >> >> +/** >> + * kasan_report - print a report about a bad memory access detected by KASAN >> + * @addr: address of the bad access >> + * @size: size of the bad access >> + * @is_write: whether the bad access is a write or a read >> + * @ip: instruction pointer for the accessibility check or the bad access itself >> + */ > > Looks good, thanks! > >> bool kasan_report(unsigned long addr, size_t size, >> bool is_write, unsigned long ip); >> >> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h >> index cc4d9e1d49b1..8c706e7652f2 100644 >> --- a/mm/kasan/kasan.h >> +++ b/mm/kasan/kasan.h >> @@ -209,7 +209,7 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, >> >> static inline bool addr_has_metadata(const void *addr) >> { >> - return true; >> + return (is_vmalloc_addr(addr) || virt_addr_valid(addr)); >> } > > Let's put this change into a separate patch. > Ok, it will be done in v4. >> >> #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ >> -- >> 2.30.0 >> -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel