Received: by 2002:a05:6a10:9848:0:0:0:0 with SMTP id x8csp1020517pxf; Thu, 25 Mar 2021 22:03:12 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxqK1kiOT2sykZ0HEljWOIQYV91lJspvF6aG+Bd60PZplwNFRKEBK+YtPoor6IOSMMuRTFl X-Received: by 2002:aa7:db53:: with SMTP id n19mr13115528edt.330.1616734992120; Thu, 25 Mar 2021 22:03:12 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1616734992; cv=none; d=google.com; s=arc-20160816; b=rVOuFLZ1FM03MrYt4vqGDEEBvdVmtvJszdpjsYsHoPhNONVkKmGJ/QJijh+HAhwj7c ZPv5IbHOIjr7qzsDXb29bOyOAhkZLu0eelU+3mDm6WeZKijBqA77BSiCxwQBnt22nqpm qYZz2q3/26/TCH53TcrZATAFO47prSrFrh+LmHvMicsCj9SlerQKzK6JeEimF/4pzi7f xGn/FNStgwl8kvbdhW/rgIg/KBBRUG6ENDtQqHFp8vMD537J+0rGtnjlvlHqcwOL+tvC gpRd7MHOF3Qu89LBOP5X8nsR5neJC8xgoZyzKR3D+X1oXQh/6Ew06UPs2heMSZzKBZO4 q5Aw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:subject:message-id:date:from:in-reply-to :references:mime-version:dkim-signature; bh=JwrtnPH682mPiw/7l+5DIhPgp7NqMdxkLw9PDd4tXfc=; b=YuModLKffAJ7ohGzZIoGuIwhWUQIBYGbLrYyUUy9mPljLJdRluyxjWiOBahzjCebSA le6BKuj6K6hUJvUwxzLwf2PZ8kmC8LjB2onWOeT00n/xsQsrL3l+KNxHM+2X9zyDGh+/ 6K46C2D84TVsgAWsp8BUvXUgEsPqKr63o4MOdLf03dGn8vDgq0CUBYiDIOe9XVOKqiDL bO4mkJxepqfn+HXv/eqIAs3eMJFtSxLn8x1yMQFINy3Uooek3k+vclTv0Fb/dFAJ82vv YhC07v61DsHM8w0HwyP9gE0+aVj14LeDw088wgI3o2hWiSXRpEfiKuniNLrbDGf0EBN9 WMHw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=ZQeWguAl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id k25si5757254ejq.186.2021.03.25.22.02.49; Thu, 25 Mar 2021 22:03:12 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=ZQeWguAl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229497AbhCZE7t (ORCPT + 99 others); Fri, 26 Mar 2021 00:59:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:58748 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229551AbhCZE7S (ORCPT ); Fri, 26 Mar 2021 00:59:18 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EFA8861A44 for ; Fri, 26 Mar 2021 04:59:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616734758; bh=dEk8ZXGgMpgPdB95Q+GWWYAMhYOliJnVarqq5EcDWEE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=ZQeWguAlR+bYr20n5WpPU3pQNOamMrLc2dnV7B4ai1NtLQ8wfs5VCmnzJ9CZVw72d 20Ng3IunT5xnNB5qrXp+V/pL/RXduKSLnEmIJAIbCWGmz5KWXWB4EvCeFOU35AH3VF YRxfWv2a7Me2xlAY1Fb0KUcXcj8jNrZB3Ei7/0S4s8bP434dFm2Kf+4IZiIRP6xBN0 fHXzjrThMDu86//C6770IBNoSBT5Ote2QNlp98A8eUGUUin8GDp6GPe1tW9BuYg4RW 6Kf/x+ed2dc0txNyJe7mnyMjUFXzdUhL4qKryJsh9YWSUrBquEZjAJzkkNYgb7IpmF McVHRrUdZ/Ydg== Received: by mail-lf1-f50.google.com with SMTP id n138so5839322lfa.3 for ; Thu, 25 Mar 2021 21:59:17 -0700 (PDT) X-Gm-Message-State: AOAM532vCI8mCndRaXJd8OcvCd5m6K7x/3/HBy/+70NXoWgeKvkitvzs 4YpABGS2YHSxbwlG04l3iOEsSmVXMT6AJpW6e1hhlA== X-Received: by 2002:a17:906:7e12:: with SMTP id e18mr13774986ejr.316.1616734745657; Thu, 25 Mar 2021 21:59:05 -0700 (PDT) MIME-Version: 1.0 References: <20210316065215.23768-1-chang.seok.bae@intel.com> <20210316065215.23768-6-chang.seok.bae@intel.com> In-Reply-To: From: Andy Lutomirski Date: Thu, 25 Mar 2021 21:58:54 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate signal stack overflow To: Andy Lutomirski Cc: Andrew Cooper , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , Borislav Petkov , Thomas Gleixner , Ingo Molnar , X86 ML , Len Brown , Dave Hansen , "H. J. Lu" , Dave Martin , Jann Horn , Michael Ellerman , "Carlos O'Donell" , Tony Luck , "Ravi V. Shankar" , libc-alpha , linux-arch , Linux API , LKML , "Bae, Chang Seok" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I forgot to mention why I cc'd all you fine Xen folk: On Thu, Mar 25, 2021 at 11:13 AM Andy Lutomirski wrote: > > > } else if (IS_ENABLED(CONFIG_X86_32) && > > !onsigstack && > > regs->ss != __USER_DS && This bit here seems really dubious on Xen PV. Honestly it seems dubious everywhere, but especially on Xen PV. --Andy