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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4305FC433F5 for ; Mon, 4 Oct 2021 13:08:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C6B061B4B for ; Mon, 4 Oct 2021 13:08:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235397AbhJDNKY (ORCPT ); Mon, 4 Oct 2021 09:10:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:45454 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235720AbhJDNI5 (ORCPT ); Mon, 4 Oct 2021 09:08:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9A31161B53; Mon, 4 Oct 2021 13:02:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1633352577; bh=Qpw+0JOAtXvF72nD6YO8s0qWtGz7d9UoqHaDKv3er18=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lt1mizUGgvMbWUF/IGudCQimAv8RtW0WHQ4bou0Wcxo918crA4Pydcog9KT3LZuW9 4o3JC/ypk+gdM6+aIApo+mNCAKXWLHbBHvRHNIy6a8uatGunsrMZceteZAqVAAvGTp 0BwELoQf7047mIFDf8t/6ov2mrVV5pTqbvjtFzMg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guenter Roeck , "David S. Miller" , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 40/95] sparc: avoid stringop-overread errors Date: Mon, 4 Oct 2021 14:52:10 +0200 Message-Id: <20211004125034.889749080@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211004125033.572932188@linuxfoundation.org> References: <20211004125033.572932188@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 51028abe5e90..ecec6a616e0d 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -40,6 +40,7 @@ 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 { @@ -613,7 +614,7 @@ EXPORT_SYMBOL(mdesc_get_node_info); 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) -- 2.33.0