From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754565AbdBEUXR (ORCPT + 2 others); Sun, 5 Feb 2017 15:23:17 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:27559 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753035AbdBETXS (ORCPT ); Sun, 5 Feb 2017 14:23:18 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Al Viro , Willy Tarreau Subject: [PATCH 3.10 090/319] asm-generic: make copy_from_user() zero the destination properly Date: Sun, 5 Feb 2017 20:21:17 +0100 Message-Id: <1486322486-8024-61-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322486-8024-1-git-send-email-w@1wt.eu> References: <1486322486-8024-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 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 [wt: s/might_fault/might_sleep] Signed-off-by: Willy Tarreau --- include/asm-generic/uaccess.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h index fee282a..a820304 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -259,11 +259,13 @@ extern int __get_user_bad(void) __attribute__((noreturn)); 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, -- 2.8.0.rc2.1.gbe9624a