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=-3.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 B69F2C43381 for ; Mon, 25 Feb 2019 12:53:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 84DEA2146F for ; Mon, 25 Feb 2019 12:53:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jAFbZwJM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727079AbfBYMxV (ORCPT ); Mon, 25 Feb 2019 07:53:21 -0500 Received: from merlin.infradead.org ([205.233.59.134]:39426 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727029AbfBYMxQ (ORCPT ); Mon, 25 Feb 2019 07:53:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=tH2zk9Q9xKncZKqbRrrR6Wex8uiJgY7ibqKzmn47QAI=; b=jAFbZwJMgUB8KzkOQHG3dkLfi/ zyOk2XWa4PkbTCRlCHklkUxull6lX6IrAbd7naMunESx5/IyeytWONWdv6bGumzansvUV11BIc5fK b/LjCYgOpdWwe5UDjEsib332cvt6rUGoLkAdk6poFXnIzc66kBOaSmBtY143LwVcYsKDSgFkZIjPX FraA+NF8S0NnOJuasSFM1uJZ+SMMVpfv2BCYeUYf/TgOn38ByeH2C8CBho+aMWVGs7bxvW1yo7V8a ALfKTpjnWX9gmqDdzVMFqfG8OHjfyvztUNvErGrhJ8fXMueWMWwCebzFxG6/zohx0wjsm/LQHcEbm TBvKLRVA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gyFkm-0006MM-5O; Mon, 25 Feb 2019 12:53:04 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 9B40B2030E108; Mon, 25 Feb 2019 13:53:02 +0100 (CET) Message-Id: <20190225125231.936952143@infradead.org> User-Agent: quilt/0.65 Date: Mon, 25 Feb 2019 13:43:32 +0100 From: Peter Zijlstra To: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net, mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, valentin.schneider@arm.com, brgerst@gmail.com, jpoimboe@redhat.com, luto@kernel.org, bp@alien8.de, dvlasenk@redhat.com Cc: linux-kernel@vger.kernel.org, peterz@infradead.org Subject: [PATCH 2/6] x86/ia32: Fix ia32_restore_sigcontext AC leak References: <20190225124330.613028745@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Don't call load_gs_index() with AC set; delay the segment setting until after the AC section. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/ia32/ia32_signal.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -60,17 +60,21 @@ regs->seg = GET_SEG(seg) | 3; \ } while (0) -#define RELOAD_SEG(seg) { \ - unsigned int pre = GET_SEG(seg); \ - unsigned int cur = get_user_seg(seg); \ - pre |= 3; \ - if (pre != cur) \ - set_user_seg(seg, pre); \ +#define LOAD_SEG(seg) { \ + pre_##seg = 3 | GET_SEG(seg); \ + cur_##seg = get_user_seg(seg); \ +} + +#define RELOAD_SEG(seg) { \ + if (pre_##seg != cur_##seg) \ + set_user_seg(seg, pre_##seg); \ } static int ia32_restore_sigcontext(struct pt_regs *regs, struct sigcontext_32 __user *sc) { + u16 pre_gs, pre_fs, pre_ds, pre_es; + u16 cur_gs, cur_fs, cur_ds, cur_es; unsigned int tmpflags, err = 0; void __user *buf; u32 tmp; @@ -85,10 +89,10 @@ static int ia32_restore_sigcontext(struc * the handler, but does not clobber them at least in the * normal case. */ - RELOAD_SEG(gs); - RELOAD_SEG(fs); - RELOAD_SEG(ds); - RELOAD_SEG(es); + LOAD_SEG(gs); + LOAD_SEG(fs); + LOAD_SEG(ds); + LOAD_SEG(es); COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); COPY(dx); COPY(cx); COPY(ip); COPY(ax); @@ -106,6 +110,11 @@ static int ia32_restore_sigcontext(struc buf = compat_ptr(tmp); } get_user_catch(err); + RELOAD_SEG(gs); + RELOAD_SEG(fs); + RELOAD_SEG(ds); + RELOAD_SEG(es); + err |= fpu__restore_sig(buf, 1); force_iret();