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=-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 E3F83C48BC2 for ; Wed, 23 Jun 2021 22:10:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C20D8611C9 for ; Wed, 23 Jun 2021 22:10:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231346AbhFWWNP (ORCPT ); Wed, 23 Jun 2021 18:13:15 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:40250 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231207AbhFWWMA (ORCPT ); Wed, 23 Jun 2021 18:12:00 -0400 Date: Wed, 23 Jun 2021 22:09:38 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624486179; 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=O1jK/uvgtsEF8s7CNbb0A1lNAQJLEKIS0orkdT++wt0=; b=hBanWkv6R77O+948FZp+mojTEIUPxB5ImPjdFRtqCeaueeEArtAa3Fpu4fW35VUovYH57n aOMAaSFFVLkPYRbNF7pzvDP9edt1hj5USws+OmzX1diF8pwo79pGXqtW7BjD93qosfgkGJ pkEbvSZj86b4fGETS/S9SLreuatK6hvhMFowsj5YKXx9V0uvRV4JoQ8t37mw8wGQ/1aem7 4c9MUUYx0XYfALZN5V89AEVS6ddJ3LNh0Qa9kN9PnMjShaUL9MO/QUrkPzkEbMzXk70Os+ m5ZsAVbqODTzlE7/JiH/GDTnv7xSqgeQMiYEvPW5DUR+hhH3Ibp0IugcY8L6Pg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624486179; 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=O1jK/uvgtsEF8s7CNbb0A1lNAQJLEKIS0orkdT++wt0=; b=rlXhNGkX7j9BxTT2RsIc0XqkWhuONZQGDZisQZnYOLmDS98mwbOYKH8T0ogS1wV07Yi1AB dv9lHHanZl2GlICw== 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/fpu] x86/fpu: Reject invalid MXCSR values in copy_kernel_to_xstate() Cc: Andy Lutomirski , Thomas Gleixner , Borislav Petkov , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210623121452.308388343@linutronix.de> References: <20210623121452.308388343@linutronix.de> MIME-Version: 1.0 Message-ID: <162448617894.395.180251854478791721.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/fpu branch of tip: Commit-ID: 947f4947cf00ea1e6d319eb182c64ea51ba4de8d Gitweb: https://git.kernel.org/tip/947f4947cf00ea1e6d319eb182c64ea51ba4de8d Author: Thomas Gleixner AuthorDate: Wed, 23 Jun 2021 14:01:37 +02:00 Committer: Borislav Petkov CommitterDate: Wed, 23 Jun 2021 17:49:46 +02:00 x86/fpu: Reject invalid MXCSR values in copy_kernel_to_xstate() Instead of masking out reserved bits, check them and reject the provided state as invalid if not zero. Suggested-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121452.308388343@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 2b7b579..9cf84c5 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1154,6 +1154,19 @@ void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave) membuf_zero(&to, to.left); } +static inline bool mxcsr_valid(struct xstate_header *hdr, const u32 *mxcsr) +{ + u64 mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM; + + /* Only check if it is in use */ + if (hdr->xfeatures & mask) { + /* Reserved bits in MXCSR must be zero. */ + if (*mxcsr & ~mxcsr_feature_mask) + return false; + } + return true; +} + /* * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S] format * and copy to the target thread. This is called from xstateregs_set(). @@ -1172,6 +1185,9 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) if (validate_user_xstate_header(&hdr)) return -EINVAL; + if (!mxcsr_valid(&hdr, kbuf + offsetof(struct fxregs_state, mxcsr))) + return -EINVAL; + for (i = 0; i < XFEATURE_MAX; i++) { u64 mask = ((u64)1 << i); @@ -1202,9 +1218,6 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) */ xsave->header.xfeatures |= hdr.xfeatures; - /* mxcsr reserved bits must be masked to zero for historical reasons. */ - xsave->i387.mxcsr &= mxcsr_feature_mask; - return 0; }