From patchwork Wed Jun 9 14:46:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: thermal-bot for Julien Panis X-Patchwork-Id: 457523 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=-20.8 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, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS 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 AE146C48BD1 for ; Wed, 9 Jun 2021 14:46:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90A64610A1 for ; Wed, 9 Jun 2021 14:46:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238157AbhFIOsq (ORCPT ); Wed, 9 Jun 2021 10:48:46 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:55002 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238111AbhFIOsp (ORCPT ); Wed, 9 Jun 2021 10:48:45 -0400 Date: Wed, 09 Jun 2021 14:46:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1623250009; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uoNSXecwPTM8KLMLKvqKdv/yoVNFbm4SZsZ81D/wnus=; b=BFwdXAQ/MUq9/OvvfimhkotJwL61rjulhUzZ1XHjbG9tCEGanE2PRVJd0xejLAPKUfClMe cuY35RlAOBIF3nrdr9deDVbxd2MVDltVFX1Rkw7sxyPZp22s1+MGCRVDbbYnOVEjyj+WnP nht38GRCBmk+fDG0l5KIb/ZETNSjSyzR/Q6os5B7MnCeHFUs4aG32nfzOBLaKgjtPW6lkK MZr8aiJgqF3+c+s7yyv1ft6QayI3yNHysgSPc4RaYx/CkCchVpS93mwOKEd5IWx4xfiyP8 R6NvGWtjsZ2EqzwvuJ/d4D+x7pFQMcpitaMvlcAW7bhvHcYkWB/EMQ/UxVcYjw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1623250009; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uoNSXecwPTM8KLMLKvqKdv/yoVNFbm4SZsZ81D/wnus=; b=h3/XVeFarSdYuEwcYV8rSuNDXethdaHJBQXOeZSt3pxJ+bScD1Og4USHMH710evAlyxuc/ AqAGASUmAi3Ug0Dw== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/fpu: Prevent state corruption in __fpu__restore_sig() Cc: syzbot+2067e764dbcd10721e2e@syzkaller.appspotmail.com, Thomas Gleixner , Borislav Petkov , Dave Hansen , Rik van Riel , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210608144345.611833074@linutronix.de> References: <20210608144345.611833074@linutronix.de> MIME-Version: 1.0 Message-ID: <162325000866.29796.4167433091280111109.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 484cea4f362e1eeb5c869abbfb5f90eae6421b38 Gitweb: https://git.kernel.org/tip/484cea4f362e1eeb5c869abbfb5f90eae6421b38 Author: Thomas Gleixner AuthorDate: Tue, 08 Jun 2021 16:36:18 +02:00 Committer: Borislav Petkov CommitterDate: Wed, 09 Jun 2021 09:28:21 +02:00 x86/fpu: Prevent state corruption in __fpu__restore_sig() The non-compacted slowpath uses __copy_from_user() and copies the entire user buffer into the kernel buffer, verbatim. This means that the kernel buffer may now contain entirely invalid state on which XRSTOR will #GP. validate_user_xstate_header() can detect some of that corruption, but that leaves the onus on callers to clear the buffer. Prior to XSAVES support, it was possible just to reinitialize the buffer, completely, but with supervisor states that is not longer possible as the buffer clearing code split got it backwards. Fixing that is possible but not corrupting the state in the first place is more robust. Avoid corruption of the kernel XSAVE buffer by using copy_user_to_xstate() which validates the XSAVE header contents before copying the actual states to the kernel. copy_user_to_xstate() was previously only called for compacted-format kernel buffers, but it works for both compacted and non-compacted forms. Using it for the non-compacted form is slower because of multiple __copy_from_user() operations, but that cost is less important than robust code in an already slow path. [ Changelog polished by Dave Hansen ] Fixes: b860eb8dce59 ("x86/fpu/xstate: Define new functions for clearing fpregs and xstates") Reported-by: syzbot+2067e764dbcd10721e2e@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Acked-by: Dave Hansen Acked-by: Rik van Riel Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210608144345.611833074@linutronix.de --- arch/x86/kernel/fpu/signal.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index a4ec653..d5bc96a 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -405,14 +405,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) if (use_xsave() && !fx_only) { u64 init_bv = xfeatures_mask_user() & ~user_xfeatures; - if (using_compacted_format()) { - ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx); - } else { - ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size); - - if (!ret && state_size > offsetof(struct xregs_state, header)) - ret = validate_user_xstate_header(&fpu->state.xsave.header); - } + ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx); if (ret) goto err_out;