From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH] net: af_packet: Validate parameter size for PACKET_HDRLEN control message Date: Wed, 27 Feb 2013 21:22:17 +0100 Message-ID: <512E6AF9.3030901@redhat.com> References: <1361994418-1403-1-git-send-email-linux@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, "David S. Miller" To: Guenter Roeck Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7337 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752945Ab3B0UWZ (ORCPT ); Wed, 27 Feb 2013 15:22:25 -0500 In-Reply-To: <1361994418-1403-1-git-send-email-linux@roeck-us.net> Sender: netdev-owner@vger.kernel.org List-ID: On 02/27/2013 08:46 PM, Guenter Roeck wrote: > Building af_packet may fail with > > In function =E2=80=98copy_from_user=E2=80=99, > inlined from =E2=80=98packet_getsockopt=E2=80=99 at > net/packet/af_packet.c:3215:21: > arch/x86/include/asm/uaccess_32.h:211:26: error: call to > =E2=80=98copy_from_user_overflow=E2=80=99 declared with attribut= e error: copy_from_user() > buffer size is not provably correct > > if built with W=3D1 due to a missing parameter size validation. > > Signed-off-by: Guenter Roeck > --- > 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 c7bfeff..1976b23 100644 > --- a/net/packet/af_packet.c > +++ b/net/packet/af_packet.c > @@ -3210,6 +3210,8 @@ static int packet_getsockopt(struct socket *soc= k, int level, int optname, > val =3D po->tp_version; > break; > case PACKET_HDRLEN: > + if (len < sizeof(int)) > + return -EINVAL; I think this could break some user space applications here, those who e= =2Eg. only pass an uint16_t to packet_getsockopt with PACKET_HDRLEN. > if (len > sizeof(int)) > len =3D sizeof(int); > if (copy_from_user(&val, optval, len))