From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757257Ab3CYB3s (ORCPT ); Sun, 24 Mar 2013 21:29:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33951 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755953Ab3CYBP4 (ORCPT ); Sun, 24 Mar 2013 21:15:56 -0400 Message-Id: <20130325010530.887150435@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 25 Mar 2013 01:06:31 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, CQ Tang , Mike Marciniszyn , "H. Peter Anvin" Subject: [ 067/104] x86-64: Fix the failure case in copy_user_handle_tail() Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In-Reply-To: <20130325010524.240972766@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:f137:78a:b654:affb 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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: CQ Tang commit 66db3feb486c01349f767b98ebb10b0c3d2d021b upstream. The increment of "to" in copy_user_handle_tail() will have incremented before a failure has been noted. This causes us to skip a byte in the failure case. Only do the increment when assured there is no failure. Signed-off-by: CQ Tang Link: http://lkml.kernel.org/r/20130318150221.8439.993.stgit@phlsvslse11.ph.intel.com Signed-off-by: Mike Marciniszyn Signed-off-by: H. Peter Anvin Signed-off-by: Ben Hutchings --- arch/x86/lib/usercopy_64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -169,10 +169,10 @@ copy_user_handle_tail(char *to, char *fr char c; unsigned zero_len; - for (; len; --len) { + for (; len; --len, to++) { if (__get_user_nocheck(c, from++, sizeof(char))) break; - if (__put_user_nocheck(c, to++, sizeof(char))) + if (__put_user_nocheck(c, to, sizeof(char))) break; }