From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756046Ab3ILRtw (ORCPT ); Thu, 12 Sep 2013 13:49:52 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56726 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755331Ab3ILRp3 (ORCPT ); Thu, 12 Sep 2013 13:45:29 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Carpenter , "Michael S. Tsirkin" , Neil Horman , "David S. Miller" Subject: [ 10/23] tun: signedness bug in tun_get_user() Date: Thu, 12 Sep 2013 10:45:06 -0700 Message-Id: <20130912174452.868503548@linuxfoundation.org> X-Mailer: git-send-email 1.8.4.3.gca3854a In-Reply-To: <20130912174451.748805761@linuxfoundation.org> References: <20130912174451.748805761@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Carpenter [ Upstream commit 15718ea0d844e4816dbd95d57a8a0e3e264ba90e ] The recent fix d9bf5f1309 "tun: compare with 0 instead of total_len" is not totally correct. Because "len" and "sizeof()" are size_t type, that means they are never less than zero. Signed-off-by: Dan Carpenter Acked-by: Michael S. Tsirkin Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -615,8 +615,9 @@ static ssize_t tun_get_user(struct tun_s int offset = 0; if (!(tun->flags & TUN_NO_PI)) { - if ((len -= sizeof(pi)) > count) + if (len < sizeof(pi)) return -EINVAL; + len -= sizeof(pi); if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi))) return -EFAULT; @@ -624,8 +625,9 @@ static ssize_t tun_get_user(struct tun_s } if (tun->flags & TUN_VNET_HDR) { - if ((len -= tun->vnet_hdr_sz) > count) + if (len < tun->vnet_hdr_sz) return -EINVAL; + len -= tun->vnet_hdr_sz; if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso))) return -EFAULT;