From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752171AbdITExA (ORCPT ); Wed, 20 Sep 2017 00:53:00 -0400 Received: from fldsmtpe03.verizon.com ([140.108.26.142]:15951 "EHLO fldsmtpe03.verizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751946AbdITEqb (ORCPT ); Wed, 20 Sep 2017 00:46:31 -0400 From: "Levin, Alexander (Sasha Levin)" Cc: Alexander Potapenko , "David S . Miller" , "Levin, Alexander (Sasha Levin)" X-Host: ranger.odc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH review for 4.4 32/47] net/packet: check length in getsockopt() called with PACKET_HDRLEN Thread-Topic: [PATCH review for 4.4 32/47] net/packet: check length in getsockopt() called with PACKET_HDRLEN Thread-Index: AQHTMcs7rtsXm0RD/kKP38npiaaAyg== Date: Wed, 20 Sep 2017 04:45:07 +0000 Message-ID: <20170920044445.7392-32-alexander.levin@verizon.com> References: <20170920044445.7392-1-alexander.levin@verizon.com> In-Reply-To: <20170920044445.7392-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v8K4r3UK024914 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 --- 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 148ec130d99d..b70055fc30cb 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3802,6 +3802,8 @@ 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) { -- 2.11.0