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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 2ECD5ECDE46 for ; Sun, 4 Nov 2018 13:54:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA7C92085B for ; Sun, 4 Nov 2018 13:54:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="q390avwr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA7C92085B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731717AbeKDXJ2 (ORCPT ); Sun, 4 Nov 2018 18:09:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:49222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731705AbeKDXJ1 (ORCPT ); Sun, 4 Nov 2018 18:09:27 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E15E2086C; Sun, 4 Nov 2018 13:54:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541339663; bh=XhnytXMPlUsaEpRiIup1v9RPbaGi4TCWYQ+alomLy2Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q390avwrB9rf1NUZz5AII4ziMjYwLEV9YWymY/QHADqsEeUdfOUuD7PdmPY3cGwVY YOfqnmah5nP5BP/Wk540dM+xXnKrJsCDI0nAg0tcMr/JcCWsmkHcglMW7iA5B3xxX8 5BJSDpSl132hdTAZBmGdflAQlUsX3YVNyuo9KBEI= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Daniel Axtens , Michael Ellerman , Sasha Levin Subject: [PATCH AUTOSEL 4.4 04/15] powerpc/nohash: fix undefined behaviour when testing page size support Date: Sun, 4 Nov 2018 08:54:06 -0500 Message-Id: <20181104135417.88671-4-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181104135417.88671-1-sashal@kernel.org> References: <20181104135417.88671-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Axtens [ Upstream commit f5e284803a7206d43e26f9ffcae5de9626d95e37 ] When enumerating page size definitions to check hardware support, we construct a constant which is (1U << (def->shift - 10)). However, the array of page size definitions is only initalised for various MMU_PAGE_* constants, so it contains a number of 0-initialised elements with def->shift == 0. This means we end up shifting by a very large number, which gives the following UBSan splat: ================================================================================ UBSAN: Undefined behaviour in /home/dja/dev/linux/linux/arch/powerpc/mm/tlb_nohash.c:506:21 shift exponent 4294967286 is too large for 32-bit type 'unsigned int' CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc3-00045-ga604f927b012-dirty #6 Call Trace: [c00000000101bc20] [c000000000a13d54] .dump_stack+0xa8/0xec (unreliable) [c00000000101bcb0] [c0000000004f20a8] .ubsan_epilogue+0x18/0x64 [c00000000101bd30] [c0000000004f2b10] .__ubsan_handle_shift_out_of_bounds+0x110/0x1a4 [c00000000101be20] [c000000000d21760] .early_init_mmu+0x1b4/0x5a0 [c00000000101bf10] [c000000000d1ba28] .early_setup+0x100/0x130 [c00000000101bf90] [c000000000000528] start_here_multiplatform+0x68/0x80 ================================================================================ Fix this by first checking if the element exists (shift != 0) before constructing the constant. Signed-off-by: Daniel Axtens Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/mm/tlb_nohash.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/powerpc/mm/tlb_nohash.c b/arch/powerpc/mm/tlb_nohash.c index bb04e4df3100..1b784b8fd8b4 100644 --- a/arch/powerpc/mm/tlb_nohash.c +++ b/arch/powerpc/mm/tlb_nohash.c @@ -487,6 +487,9 @@ static void setup_page_sizes(void) for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) { struct mmu_psize_def *def = &mmu_psize_defs[psize]; + if (!def->shift) + continue; + if (tlb1ps & (1U << (def->shift - 10))) { def->flags |= MMU_PAGE_SIZE_DIRECT; -- 2.17.1