Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753977AbdHKWNg (ORCPT ); Fri, 11 Aug 2017 18:13:36 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33326 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753627AbdHKWB6 (ORCPT ); Fri, 11 Aug 2017 18:01:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrey Konovalov , Willem de Bruijn , "David S. Miller" Subject: [PATCH 4.9 11/16] packet: fix tp_reserve race in packet_set_ring Date: Fri, 11 Aug 2017 15:01:41 -0700 Message-Id: <20170811220133.193231868@linuxfoundation.org> X-Mailer: git-send-email 2.14.0 In-Reply-To: <20170811220132.730037644@linuxfoundation.org> References: <20170811220132.730037644@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 Content-Length: 1385 Lines: 51 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn [ Upstream commit c27927e372f0785f3303e8fad94b85945e2c97b7 ] Updates to tp_reserve can race with reads of the field in packet_set_ring. Avoid this by holding the socket lock during updates in setsockopt PACKET_RESERVE. This bug was discovered by syzkaller. Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") Reported-by: Andrey Konovalov Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3698,14 +3698,19 @@ packet_setsockopt(struct socket *sock, i if (optlen != sizeof(val)) return -EINVAL; - if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) - return -EBUSY; if (copy_from_user(&val, optval, sizeof(val))) return -EFAULT; if (val > INT_MAX) return -EINVAL; - po->tp_reserve = val; - return 0; + lock_sock(sk); + if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) { + ret = -EBUSY; + } else { + po->tp_reserve = val; + ret = 0; + } + release_sock(sk); + return ret; } case PACKET_LOSS: {