From patchwork Mon Jan 18 11:34:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 366834 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=-18.8 required=3.0 tests=BAYES_00,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 974FCC433E0 for ; Mon, 18 Jan 2021 19:16:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6651022573 for ; Mon, 18 Jan 2021 19:16:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390475AbhARLid (ORCPT ); Mon, 18 Jan 2021 06:38:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:33334 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390452AbhARLiY (ORCPT ); Mon, 18 Jan 2021 06:38:24 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2B9EC2245C; Mon, 18 Jan 2021 11:37:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610969854; bh=PGVt/uwhb/VpQsf7HIsOOMkO7FiMHcLIxoVXDsofli8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DK8YHluoZuuEO0bkpEUDYbgkxbUyJ/RAl9z73Qwpc67Q1ugwhCNOSU1UKP2wBKANU +TD1aFKpn/LkVaCnHEgD9mqeMKYVggjFakH8mytTTdpr0DNqVhG168ARYjlXgn9k8k Gx8/CBXBH/fjN3bnCv+8iVHZGoEne56P3Xo1ZP0A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Lobakin , Nathan Chancellor , Kees Cook , Thomas Bogendoerfer Subject: [PATCH 5.4 10/76] MIPS: relocatable: fix possible boot hangup with KASLR enabled Date: Mon, 18 Jan 2021 12:34:10 +0100 Message-Id: <20210118113341.480490699@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210118113340.984217512@linuxfoundation.org> References: <20210118113340.984217512@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Alexander Lobakin commit 69e976831cd53f9ba304fd20305b2025ecc78eab upstream. LLVM-built Linux triggered a boot hangup with KASLR enabled. arch/mips/kernel/relocate.c:get_random_boot() uses linux_banner, which is a string constant, as a random seed, but accesses it as an array of unsigned long (in rotate_xor()). When the address of linux_banner is not aligned to sizeof(long), such access emits unaligned access exception and hangs the kernel. Use PTR_ALIGN() to align input address to sizeof(long) and also align down the input length to prevent possible access-beyond-end. Fixes: 405bc8fd12f5 ("MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE") Cc: stable@vger.kernel.org # 4.7+ Signed-off-by: Alexander Lobakin Tested-by: Nathan Chancellor Reviewed-by: Kees Cook Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman --- arch/mips/kernel/relocate.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/arch/mips/kernel/relocate.c +++ b/arch/mips/kernel/relocate.c @@ -187,8 +187,14 @@ static int __init relocate_exception_tab static inline __init unsigned long rotate_xor(unsigned long hash, const void *area, size_t size) { - size_t i; - unsigned long *ptr = (unsigned long *)area; + const typeof(hash) *ptr = PTR_ALIGN(area, sizeof(hash)); + size_t diff, i; + + diff = (void *)ptr - area; + if (unlikely(size < diff + sizeof(hash))) + return hash; + + size = ALIGN_DOWN(size - diff, sizeof(hash)); for (i = 0; i < size / sizeof(hash); i++) { /* Rotate by odd number of bits and XOR. */