Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936187AbcKNDEK (ORCPT ); Sun, 13 Nov 2016 22:04:10 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46367 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754259AbcKNCF7 (ORCPT ); Sun, 13 Nov 2016 21:05:59 -0500 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, "Al Viro" Date: Mon, 14 Nov 2016 00:14:07 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 101/152] asm-generic: make copy_from_user() zero the destination properly In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 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 Content-Length: 1238 Lines: 41 3.2.84-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro commit 2545e5da080b4839dd859e3b09343a884f6ab0e3 upstream. ... in all cases, including the failing access_ok() Note that some architectures using asm-generic/uaccess.h have __copy_from_user() not zeroing the tail on failure halfway through. This variant works either way. Signed-off-by: Al Viro [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- include/asm-generic/uaccess.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -243,11 +243,13 @@ extern int __get_user_bad(void) __attrib static inline long copy_from_user(void *to, const void __user * from, unsigned long n) { + unsigned long res = n; might_sleep(); - if (access_ok(VERIFY_READ, from, n)) - return __copy_from_user(to, from, n); - else - return n; + if (likely(access_ok(VERIFY_READ, from, n))) + res = __copy_from_user(to, from, n); + if (unlikely(res)) + memset(to + (n - res), 0, res); + return res; } static inline long copy_to_user(void __user *to,