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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 F2B70C43381 for ; Sun, 3 Mar 2019 17:05:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF48A20818 for ; Sun, 3 Mar 2019 17:05:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jae9ZA08" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726416AbfCCRFX (ORCPT ); Sun, 3 Mar 2019 12:05:23 -0500 Received: from mail-ed1-f68.google.com ([209.85.208.68]:47021 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726293AbfCCRFX (ORCPT ); Sun, 3 Mar 2019 12:05:23 -0500 Received: by mail-ed1-f68.google.com with SMTP id f2so2284708edy.13 for ; Sun, 03 Mar 2019 09:05:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=l6cy6YYG3R5hxNTZ+RaUd4D4QyOceO0d8jXAu+Xq9Sc=; b=jae9ZA08wm8NqVx9aTgPGXAFI/hn1AyGKbLaTk5qpK2r4c7JHMFz3Gv3jB3w1pFLN5 8nAEKFjW8ujPGl9e2O7E1K2wfTaKheMa5J/1PR05ff/xfthcQlDIc6yEzsLJDLTg7hn2 pMFtg+RP7pF0N2lK1EIas8BL7p6e1nswKBBJnjT+mGyfsA7mujdgpzcBIaQmGvnt/U/b 0/9k6eqKNXot8TYgFVPUKQSh+qYOMBcYQ5XsdCRM64qPXB8fKIWVwqRAeoezd4w0perl NpDSiDxY3iCz67oi3ftJsGZi6+5YCggnQYU5w9GBZq6gJQxo79t4clHG9OdXw6fIlheo C+Qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=l6cy6YYG3R5hxNTZ+RaUd4D4QyOceO0d8jXAu+Xq9Sc=; b=Q3RVJR8TpfXP4JsntLgrLZHaAExXRhGPy/Pavu31Q6DT7aVqUAU3WUxrssEGt8q5io ruQd/9yMMXnwa22Sgvr3aLW7QiEJnJG4BG0sgWDS1cVSXyCXLG5loLUQ8yyE28mvZ36Y 1Zw5zyGh2zPedNPidRet+OPVJ2NQSyhkkbF4MALkrgP0pKHGFOVk5W/9bBf3USNQe5hG jqKaag41Kr0H1xABpzz9GQAk3yIlpFKAb+eyNMq6NWX3aILHIMMSCCY4wxK9h/FhmZX9 DTewCLaNw7A1y+N0zNoCsX/urqEf9g2gy5VE3eQhTh0bpE989L2B1BA2he5PFZaASnLN C3ZA== X-Gm-Message-State: APjAAAXHsHQIJYbjyMnXmLSZhNeJ8u0yzoAAGrTa+CYL36JBD1YHY8nj 0oa/NAmLzPUoagDa/c7Pggw= X-Google-Smtp-Source: APXvYqzJK4yggVKxaTQnRTqj9RlphVnkbbyC59XZhiMW750yFkaudhpOqYlrpbAhuTisLEvwUFpghw== X-Received: by 2002:a17:906:860e:: with SMTP id o14mr5295745ejx.202.1551632720678; Sun, 03 Mar 2019 09:05:20 -0800 (PST) Received: from archlinux-ryzen ([2a01:4f9:2a:1fae::2]) by smtp.gmail.com with ESMTPSA id g25sm742036ejc.55.2019.03.03.09.05.19 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sun, 03 Mar 2019 09:05:20 -0800 (PST) Date: Sun, 3 Mar 2019 10:05:18 -0700 From: Nathan Chancellor To: Maxim Zhukov Cc: Greg Kroah-Hartman , Andy Lutomirski , Borislav Petkov , Linus Torvalds , Peter Zijlstra , Brian Gerst , Josh Poimboeuf , Denys Vlasenko , stable@vger.kernel.org Subject: Re: [PATCH v4.4] x86/uaccess: Don't leak the AC flag into __put_user() value evaluation Message-ID: <20190303170518.GA2372@archlinux-ryzen> References: <20190303160709.19426-1-mussitantesmortem@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190303160709.19426-1-mussitantesmortem@gmail.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sun, Mar 03, 2019 at 07:07:09PM +0300, Maxim Zhukov wrote: > From: Andy Lutomirski > > commit 2a418cf3f5f1caf911af288e978d61c9844b0695 upstream. > > When calling __put_user(foo(), ptr), the __put_user() macro would call > foo() in between __uaccess_begin() and __uaccess_end(). If that code > were buggy, then those bugs would be run without SMAP protection. > > Fortunately, there seem to be few instances of the problem in the > kernel. Nevertheless, __put_user() should be fixed to avoid doing this. > Therefore, evaluate __put_user()'s argument before setting AC. > > This issue was noticed when an objtool hack by Peter Zijlstra complained > about genregs_get() and I compared the assembly output to the C source. > > [ bp: Massage commit message and fixed up whitespace. ] > > Fixes: 11f1a4b9755f ("x86: reorganize SMAP handling in user space accesses") > Signed-off-by: Andy Lutomirski > Signed-off-by: Borislav Petkov > Acked-by: Linus Torvalds > Cc: Peter Zijlstra > Cc: Brian Gerst > Cc: Josh Poimboeuf > Cc: Denys Vlasenko > Cc: stable@vger.kernel.org > Link: http://lkml.kernel.org/r/20190225125231.845656645@infradead.org > Signed-off-by: Maxim Zhukov > --- > arch/x86/include/asm/uaccess.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > index d788b0cdc0ad..4f4a9fa61b8a 100644 > --- a/arch/x86/include/asm/uaccess.h > +++ b/arch/x86/include/asm/uaccess.h > @@ -306,7 +306,7 @@ do { \ > __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \ > break; \ > case 8: \ > - __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \ > + __put_user_asm_u64(x, ptr, retval, \ > errret); \ > break; \ > default: \ > @@ -410,7 +410,9 @@ do { \ > #define __put_user_nocheck(x, ptr, size) \ > ({ \ > int __pu_err; \ > - __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \ > + __typeof__(*(ptr)) __pu_val; \ > + __pu_val = x; \ > + __put_user_size(__pu_val, (ptr), (size), __pu_err, -EFAULT); \ > __builtin_expect(__pu_err, 0); \ > }) > > -- > 2.21.0 > Did you generate this against a current 4.4 tree? It fails to apply to 4.4.176 because this patch doesn't account for cc8c5450b6d7 ("x86: reorganize SMAP handling in user space accesses"). Odds are you will only need one patch for 4.4 to 4.20. Cheers, Nathan