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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 6A85BC49ED7 for ; Fri, 20 Sep 2019 14:36:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B577206C2 for ; Fri, 20 Sep 2019 14:36:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392091AbfITOgY (ORCPT ); Fri, 20 Sep 2019 10:36:24 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35864 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388065AbfITOZB (ORCPT ); Fri, 20 Sep 2019 10:25:01 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iBJqE-0004y7-Lm; Fri, 20 Sep 2019 15:24:58 +0100 Received: from ben by deadeye with local (Exim 4.92.1) (envelope-from ) id 1iBJqE-0007s6-26; Fri, 20 Sep 2019 15:24:58 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , luto@kernel.org, "Peter Zijlstra" , "Linus Torvalds" , "Randy Dunlap" , "Ingo Molnar" , "Thomas Gleixner" Date: Fri, 20 Sep 2019 15:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 044/132] x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.74-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra commit 6ae865615fc43d014da2fd1f1bba7e81ee622d1b upstream. The __put_user() macro evaluates it's @ptr argument inside the __uaccess_begin() / __uaccess_end() region. While this would normally not be expected to be an issue, an UBSAN bug (it ignored -fwrapv, fixed in GCC 8+) would transform the @ptr evaluation for: drivers/gpu/drm/i915/i915_gem_execbuffer.c: if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) { into a signed-overflow-UB check and trigger the objtool AC validation. Finish this commit: 2a418cf3f5f1 ("x86/uaccess: Don't leak the AC flag into __put_user() value evaluation") and explicitly evaluate all 3 arguments early. Reported-by: Randy Dunlap Signed-off-by: Peter Zijlstra (Intel) Acked-by: Randy Dunlap # build-tested Acked-by: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: luto@kernel.org Fixes: 2a418cf3f5f1 ("x86/uaccess: Don't leak the AC flag into __put_user() value evaluation") Link: http://lkml.kernel.org/r/20190424072208.695962771@infradead.org Signed-off-by: Ingo Molnar [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- arch/x86/include/asm/uaccess.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -422,10 +422,11 @@ do { \ #define __put_user_nocheck(x, ptr, size) \ ({ \ int __pu_err; \ - __typeof__(*(ptr)) __pu_val; \ - __pu_val = x; \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(ptr) __pu_ptr = (ptr); \ + __typeof__(size) __pu_size = (size); \ __uaccess_begin(); \ - __put_user_size(__pu_val, (ptr), (size), __pu_err, -EFAULT); \ + __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_err, -EFAULT); \ __uaccess_end(); \ __pu_err; \ })