From patchwork Fri Jan 22 14:10:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 369350 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=ham 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 45505C43142 for ; Fri, 22 Jan 2021 19:59:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 183A223B08 for ; Fri, 22 Jan 2021 19:59:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730788AbhAVT6s (ORCPT ); Fri, 22 Jan 2021 14:58:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:35774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728293AbhAVOOG (ORCPT ); Fri, 22 Jan 2021 09:14:06 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4082523AC6; Fri, 22 Jan 2021 14:11:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611324677; bh=xuse8mD2fn4+OxDh5gK8LjZ2y3Ni6AKx2FxEklsL1Fo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=np02vADBNdFd6mBr8tjyoHWWe39U/Ul4vGd1+X4NcIrjVT4aHgLFEC4oUBZ7DXXrx sN0PuBRi40BUlwmgwRDQYz6rOiN563mHXWveDHm5eOzGYQqADy+Kwikvcf/Mo5ZsbI w6tbU32/dEulYkMtr+mKFru22JxLYX0UkZWd2SdQ= 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 4.9 04/35] MIPS: relocatable: fix possible boot hangup with KASLR enabled Date: Fri, 22 Jan 2021 15:10:06 +0100 Message-Id: <20210122135732.522243955@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210122135732.357969201@linuxfoundation.org> References: <20210122135732.357969201@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 @@ -175,8 +175,14 @@ 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. */