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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 1B8D7C2D0A3 for ; Tue, 3 Nov 2020 21:28:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCA222074B for ; Tue, 3 Nov 2020 21:28:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604438897; bh=h8VO8aKLMLf4XmZjmCqV56IrKC+YonT/HRfwBjcxFM0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ll+/f5Kea/Z4bG5P/aD3zKVB5UvsPLlsMblJJVbHOhupiXhx3EqFlwiQ7wUcZ9oGC Y0OFbPJ8XMpD8psUiyDnLVsZvCTurS3+H/Uu76QnGlnc85NtLfg2f1jD1k3YVXiAGb DYzgtqr3RgMxmgxczVGtGNv7Oj5GAdzo5s+ciJyI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388146AbgKCV2B (ORCPT ); Tue, 3 Nov 2020 16:28:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:36240 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733199AbgKCVA2 (ORCPT ); Tue, 3 Nov 2020 16:00:28 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 34EA6223FD; Tue, 3 Nov 2020 21:00:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437227; bh=h8VO8aKLMLf4XmZjmCqV56IrKC+YonT/HRfwBjcxFM0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wjTbktvr0vqYhXBGScjD3wmujtEFYhOj29Cwgy2QVRJZZ87V4AwSxuYAq9CEdKBpL ZmmXwSJn+d5QDuSq3lktTBdXdOZsVXtxK1/SoDiCk+Vmlhnfn5OB39/nXXsFZL2x1K LlXV4b1uVdA4dCMqSTfWVURXKutvBzf5eJ1Dtayo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Neuling , Michael Ellerman Subject: [PATCH 5.4 163/214] powerpc: Fix undetected data corruption with P9N DD2.1 VSX CI load emulation Date: Tue, 3 Nov 2020 21:36:51 +0100 Message-Id: <20201103203306.048306295@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203249.448706377@linuxfoundation.org> References: <20201103203249.448706377@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: Michael Neuling commit 1da4a0272c5469169f78cd76cf175ff984f52f06 upstream. __get_user_atomic_128_aligned() stores to kaddr using stvx which is a VMX store instruction, hence kaddr must be 16 byte aligned otherwise the store won't occur as expected. Unfortunately when we call __get_user_atomic_128_aligned() in p9_hmi_special_emu(), the buffer we pass as kaddr (ie. vbuf) isn't guaranteed to be 16B aligned. This means that the write to vbuf in __get_user_atomic_128_aligned() has the bottom bits of the address truncated. This results in other local variables being overwritten. Also vbuf will not contain the correct data which results in the userspace emulation being wrong and hence undetected user data corruption. In the past we've been mostly lucky as vbuf has ended up aligned but this is fragile and isn't always true. CONFIG_STACKPROTECTOR in particular can change the stack arrangement enough that our luck runs out. This issue only occurs on POWER9 Nimbus <= DD2.1 bare metal. The fix is to align vbuf to a 16 byte boundary. Fixes: 5080332c2c89 ("powerpc/64s: Add workaround for P9 vector CI load issue") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Michael Neuling Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201013043741.743413-1-mikey@neuling.org Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/traps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -877,7 +877,7 @@ static void p9_hmi_special_emu(struct pt { unsigned int ra, rb, t, i, sel, instr, rc; const void __user *addr; - u8 vbuf[16], *vdst; + u8 vbuf[16] __aligned(16), *vdst; unsigned long ea, msr, msr_mask; bool swap;