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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 B10B8C432BE for ; Mon, 2 Aug 2021 13:46:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99D2E60FC2 for ; Mon, 2 Aug 2021 13:46:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234080AbhHBNqM (ORCPT ); Mon, 2 Aug 2021 09:46:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:55640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234058AbhHBNqK (ORCPT ); Mon, 2 Aug 2021 09:46:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 10DB560555; Mon, 2 Aug 2021 13:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627911961; bh=TLuHBacfy6zJyeCibSLTST2gSrfB2psfKd7bI6DsLCQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HeMOrsrFm62Y0jJ7Ku/U+4tFMuvXzput08Dj6hGL0GxvfR+XOILIdqikftR2V4Hia SY010Wp65eTXv+0wneOl+gkleA/MbEyvQGbR2jahta1VIcPsihmVs7eI/iotx78kXE /oi+I1H7Chb+KGMhCe8q3xZ4LQo7bMqgT/dZXsIs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Will Deacon , Russell King , "Nobuhiro Iwamatsu (CIP)" Subject: [PATCH 4.4 12/26] ARM: ensure the signal page contains defined contents Date: Mon, 2 Aug 2021 15:44:22 +0200 Message-Id: <20210802134332.437696492@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210802134332.033552261@linuxfoundation.org> References: <20210802134332.033552261@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: linux-kernel@vger.kernel.org From: Russell King commit 9c698bff66ab4914bb3d71da7dc6112519bde23e upstream. Ensure that the signal page contains our poison instruction to increase the protection against ROP attacks and also contains well defined contents. Acked-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Nobuhiro Iwamatsu (CIP) Signed-off-by: Greg Kroah-Hartman --- arch/arm/kernel/signal.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -625,18 +625,20 @@ struct page *get_signal_page(void) addr = page_address(page); + /* Poison the entire page */ + memset32(addr, __opcode_to_mem_arm(0xe7fddef1), + PAGE_SIZE / sizeof(u32)); + /* Give the signal return code some randomness */ offset = 0x200 + (get_random_int() & 0x7fc); signal_return_offset = offset; - /* - * Copy signal return handlers into the vector page, and - * set sigreturn to be a pointer to these. - */ + /* Copy signal return handlers into the page */ memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); - ptr = (unsigned long)addr + offset; - flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); + /* Flush out all instructions in this page */ + ptr = (unsigned long)addr; + flush_icache_range(ptr, ptr + PAGE_SIZE); return page; }