From patchwork Mon Mar 22 16:02:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12155267 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=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 03560C433DB for ; Mon, 22 Mar 2021 16:06:54 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 6861B619B6 for ; Mon, 22 Mar 2021 16:06:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6861B619B6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MAMiG0EmYbv6lnqFxMJADWCXJuzfIm/h/d9e6EBIWiI=; b=mf/TvzUQdkQz/BMxB00XQRk/U ka3XfjpKwdHX4OB1BasV3OmSv3nIaW1KCMxG9jTj7she6+CaAHbsXawwNiJK32wHR7BNOv0z3Ikso GDDD0T+VoGI4sQ7hEPolwc004BkBnJWsTHVe8XS73LbsCF6cuhI/qZ9MuleulbYY70pAnsB2aMiYV AI6H7ow1xq9urbxIcq57da0sQav6capxD4Wis6ZR+Y1PmUMJh9aCDzFR1DC4kQKBckAhGLkfFUxiS 9BQAQb7M69fiVzuia7RY5zLg6Dfy5uAA+2PWa/hD/FtdGRWoSnVc1GVRmarG7KpGAHMiMEOtAVUwD ggC2FtiEQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lON1x-00BxG1-T5; Mon, 22 Mar 2021 16:03:50 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lON1o-00BxDU-BY; Mon, 22 Mar 2021 16:03:43 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id BA0F66199E; Mon, 22 Mar 2021 16:03:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616429019; bh=by6x6Rsrr+/5kT7BQ0fn/CIy488q3HO6uAtxXzMMlIk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O6Jy+HmUTikJ1x1bJ304Vrp1sBfWbLm1PtId9ZJsKafzCLMEYQU//L/uQ5NyHGzrh RhBcv0KcZohevaQjWtq/m2PyDxHXZ6oO/xPHdEAeZN27qebnzt5Wg4fhtjqGJK48VY UL94XPmfJWp5a2JWF1yBFnnQqkdteTxWc08FTIpJX/wa6/CiiShyqAZe7XpjIeOmzt cO/lp91PJ7K5iDRKpXJ1LzXMgwxLeTNc1hWrW+Oj2cHQ8M1FuYfEUnJHvIMPGvZ3nY pOppyp2fEDOWTHfMFCcVXI+sMo5gidr9nyHaAyqJ/Nlnh1nTbp/etdZKIJcUsxQAJ9 FpT/4xvv9xvFg== From: Arnd Bergmann To: linux-kernel@vger.kernel.org, Martin Sebor , Ning Sun , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org Cc: Arnd Bergmann , Jani Nikula , Kalle Valo , Simon Kelley , James Smart , "James E.J. Bottomley" , Anders Larsen , Tejun Heo , Serge Hallyn , Imre Deak , linux-arm-kernel@lists.infradead.org, tboot-devel@lists.sourceforge.net, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, ath11k@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-scsi@vger.kernel.org, cgroups@vger.kernel.org, linux-security-module@vger.kernel.org, "H. Peter Anvin" , Andrew Morton , Lu Baolu , Will Deacon Subject: [PATCH 02/11] x86: tboot: avoid Wstringop-overread-warning Date: Mon, 22 Mar 2021 17:02:40 +0100 Message-Id: <20210322160253.4032422-3-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210322160253.4032422-1-arnd@kernel.org> References: <20210322160253.4032422-1-arnd@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210322_160341_142389_C4A14858 X-CRM114-Status: GOOD ( 15.89 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Arnd Bergmann gcc-11 warns about using string operations on pointers that are defined at compile time as offsets from a NULL pointer. Unfortunately that also happens on the result of fix_to_virt(), which is a compile-time constant for a constantn input: arch/x86/kernel/tboot.c: In function 'tboot_probe': arch/x86/kernel/tboot.c:70:13: error: '__builtin_memcmp_eq' specified bound 16 exceeds source size 0 [-Werror=stringop-overread] 70 | if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I hope this can get addressed in gcc-11 before the release. As a workaround, split up the tboot_probe() function in two halves to separate the pointer generation from the usage. This is a bit ugly, and hopefully gcc understands that the code is actually correct before it learns to peek into the noinline function. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 Signed-off-by: Arnd Bergmann --- arch/x86/kernel/tboot.c | 44 ++++++++++++++++++++++++----------------- 1 file changed, 26 insertions(+), 18 deletions(-) diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c index 4c09ba110204..f9af561c3cd4 100644 --- a/arch/x86/kernel/tboot.c +++ b/arch/x86/kernel/tboot.c @@ -49,6 +49,30 @@ bool tboot_enabled(void) return tboot != NULL; } +/* noinline to prevent gcc from warning about dereferencing constant fixaddr */ +static noinline __init bool check_tboot_version(void) +{ + if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) { + pr_warn("tboot at 0x%llx is invalid\n", boot_params.tboot_addr); + return false; + } + + if (tboot->version < 5) { + pr_warn("tboot version is invalid: %u\n", tboot->version); + return false; + } + + pr_info("found shared page at phys addr 0x%llx:\n", + boot_params.tboot_addr); + pr_debug("version: %d\n", tboot->version); + pr_debug("log_addr: 0x%08x\n", tboot->log_addr); + pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry); + pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base); + pr_debug("tboot_size: 0x%x\n", tboot->tboot_size); + + return true; +} + void __init tboot_probe(void) { /* Look for valid page-aligned address for shared page. */ @@ -66,25 +90,9 @@ void __init tboot_probe(void) /* Map and check for tboot UUID. */ set_fixmap(FIX_TBOOT_BASE, boot_params.tboot_addr); - tboot = (struct tboot *)fix_to_virt(FIX_TBOOT_BASE); - if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) { - pr_warn("tboot at 0x%llx is invalid\n", boot_params.tboot_addr); + tboot = (void *)fix_to_virt(FIX_TBOOT_BASE); + if (!check_tboot_version()) tboot = NULL; - return; - } - if (tboot->version < 5) { - pr_warn("tboot version is invalid: %u\n", tboot->version); - tboot = NULL; - return; - } - - pr_info("found shared page at phys addr 0x%llx:\n", - boot_params.tboot_addr); - pr_debug("version: %d\n", tboot->version); - pr_debug("log_addr: 0x%08x\n", tboot->log_addr); - pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry); - pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base); - pr_debug("tboot_size: 0x%x\n", tboot->tboot_size); } static pgd_t *tboot_pg_dir;