From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933895AbdKAVzc (ORCPT ); Wed, 1 Nov 2017 17:55:32 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:35257 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933991AbdKAV1h (ORCPT ); Wed, 1 Nov 2017 17:27:37 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Alexander Potapenko , "David S . Miller" , Willy Tarreau Subject: [PATCH 3.10 085/139] net/packet: check length in getsockopt() called with PACKET_HDRLEN Date: Wed, 1 Nov 2017 22:26:26 +0100 Message-Id: <1509571600-4858-36-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1509571600-4858-1-git-send-email-w@1wt.eu> References: <1509571159-4405-1-git-send-email-w@1wt.eu> <1509571600-4858-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Potapenko commit fd2c83b35752f0a8236b976978ad4658df14a59f upstream. 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: Willy Tarreau --- net/packet/af_packet.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 0bbb347..b915d01 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3338,6 +3338,8 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, 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) { -- 2.8.0.rc2.1.gbe9624a