From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753703AbdJFJDQ (ORCPT ); Fri, 6 Oct 2017 05:03:16 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50262 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753450AbdJFI6D (ORCPT ); Fri, 6 Oct 2017 04:58:03 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Potapenko , "David S. Miller" , Sasha Levin Subject: [PATCH 4.4 30/50] net/packet: check length in getsockopt() called with PACKET_HDRLEN Date: Fri, 6 Oct 2017 10:53:18 +0200 Message-Id: <20171006083709.980463248@linuxfoundation.org> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171006083705.157012217@linuxfoundation.org> References: <20171006083705.157012217@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Potapenko [ Upstream commit fd2c83b35752f0a8236b976978ad4658df14a59f ] In the case getsockopt() is called with PACKET_HDRLEN and optlen < 4 |val| remains uninitialized and the syscall may behave differently depending on its value, and even copy garbage to userspace on certain architectures. To fix this we now return -EINVAL if optlen is too small. This bug has been detected with KMSAN. Signed-off-by: Alexander Potapenko Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3802,6 +3802,8 @@ static int packet_getsockopt(struct sock case PACKET_HDRLEN: if (len > sizeof(int)) len = sizeof(int); + if (len < sizeof(int)) + return -EINVAL; if (copy_from_user(&val, optval, len)) return -EFAULT; switch (val) {