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=-20.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 8B4D7C4332F for ; Thu, 23 Sep 2021 03:43:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D39A60F4C for ; Thu, 23 Sep 2021 03:43:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239364AbhIWDpQ (ORCPT ); Wed, 22 Sep 2021 23:45:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:41968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239555AbhIWDnP (ORCPT ); Wed, 22 Sep 2021 23:43:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C35FA6128E; Thu, 23 Sep 2021 03:40:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632368440; bh=Bz+E8LNs8ytPWUjTlv/NsRHobPvyXzz1g8nxTX45R58=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VZk+zHOV2T0FfKhg2zEHT6sh7varw7LvcTRHpI5IcKffAAsyyc4eWxeI87A3u1tvU RaSNs2xn2NRdwJi/Pbw8I+i85MGBBHLbtfUP6OgEn7aHEjA4XuWyklunOlDuS6d5lc KvTAucPiFh69TfwD9dVkmN6q+AQHK0RJR3b+woQinWgp+CqdKxpifEqef0KhFqFD9V /gZxehVdRvYNWPxh1T/SYCLHlKePR1X8Vj8qrWHkE1MHr5Lt43WdKAr0fq9TpqCkqz e0XZl4LIxviJc9Dul0a0Hd0fWa2XeCCE6hCYqUw0KDiMGy3fIcA55TqIHv+CR65AEI bDPoGARM3rwjw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Linus Torvalds , Guenter Roeck , "David S . Miller" , Sasha Levin , sparclinux@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 05/11] sparc: avoid stringop-overread errors Date: Wed, 22 Sep 2021 23:40:21 -0400 Message-Id: <20210923034028.1421876-5-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210923034028.1421876-1-sashal@kernel.org> References: <20210923034028.1421876-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds [ Upstream commit fc7c028dcdbfe981bca75d2a7b95f363eb691ef3 ] The sparc mdesc code does pointer games with 'struct mdesc_hdr', but didn't describe to the compiler how that header is then followed by the data that the header describes. As a result, gcc is now unhappy since it does stricter pointer range tracking, and doesn't understand about how these things work. This results in various errors like: arch/sparc/kernel/mdesc.c: In function ‘mdesc_node_by_name’: arch/sparc/kernel/mdesc.c:647:22: error: ‘strcmp’ reading 1 or more bytes from a region of size 0 [-Werror=stringop-overread] 647 | if (!strcmp(names + ep[ret].name_offset, name)) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ which are easily avoided by just describing 'struct mdesc_hdr' better, and making the node_block() helper function look into that unsized data[] that follows the header. This makes the sparc64 build happy again at least for my cross-compiler version (gcc version 11.2.1). Link: https://lore.kernel.org/lkml/CAHk-=wi4NW3NC0xWykkw=6LnjQD6D_rtRtxY9g8gQAJXtQMi8A@mail.gmail.com/ Cc: Guenter Roeck Cc: David S. Miller Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- arch/sparc/kernel/mdesc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c index 8a6982dfd733..5aa33bf7139e 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -37,6 +37,7 @@ struct mdesc_hdr { u32 node_sz; /* node block size */ u32 name_sz; /* name block size */ u32 data_sz; /* data block size */ + char data[]; } __attribute__((aligned(16))); struct mdesc_elem { @@ -369,7 +370,7 @@ void mdesc_update(void) static struct mdesc_elem *node_block(struct mdesc_hdr *mdesc) { - return (struct mdesc_elem *) (mdesc + 1); + return (struct mdesc_elem *) mdesc->data; } static void *name_block(struct mdesc_hdr *mdesc) -- 2.30.2