Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753854AbcLIQWD (ORCPT ); Fri, 9 Dec 2016 11:22:03 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:55806 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933965AbcLIQV7 (ORCPT ); Fri, 9 Dec 2016 11:21:59 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Philip Pettersson , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.8 22/45] packet: fix race condition in packet_set_ring Date: Fri, 9 Dec 2016 17:20:51 +0100 Message-Id: <20161209161755.860604743@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161209161754.912203877@linuxfoundation.org> References: <20161209161754.912203877@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: 2666 Lines: 93 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Philip Pettersson [ Upstream commit 84ac7260236a49c79eede91617700174c2c19b0c ] When packet_set_ring creates a ring buffer it will initialize a struct timer_list if the packet version is TPACKET_V3. This value can then be raced by a different thread calling setsockopt to set the version to TPACKET_V1 before packet_set_ring has finished. This leads to a use-after-free on a function pointer in the struct timer_list when the socket is closed as the previously initialized timer will not be deleted. The bug is fixed by taking lock_sock(sk) in packet_setsockopt when changing the packet version while also taking the lock at the start of packet_set_ring. Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.") Signed-off-by: Philip Pettersson Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3648,19 +3648,25 @@ 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; switch (val) { case TPACKET_V1: case TPACKET_V2: case TPACKET_V3: - po->tp_version = val; - return 0; + break; default: return -EINVAL; } + lock_sock(sk); + if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) { + ret = -EBUSY; + } else { + po->tp_version = val; + ret = 0; + } + release_sock(sk); + return ret; } case PACKET_RESERVE: { @@ -4164,6 +4170,7 @@ static int packet_set_ring(struct sock * /* Added to avoid minimal code churn */ struct tpacket_req *req = &req_u->req; + lock_sock(sk); /* Opening a Tx-ring is NOT supported in TPACKET_V3 */ if (!closing && tx_ring && (po->tp_version > TPACKET_V2)) { net_warn_ratelimited("Tx-ring is not supported.\n"); @@ -4245,7 +4252,6 @@ static int packet_set_ring(struct sock * goto out; } - lock_sock(sk); /* Detach socket from network */ spin_lock(&po->bind_lock); @@ -4294,11 +4300,11 @@ static int packet_set_ring(struct sock * if (!tx_ring) prb_shutdown_retire_blk_timer(po, rb_queue); } - release_sock(sk); if (pg_vec) free_pg_vec(pg_vec, order, req->tp_block_nr); out: + release_sock(sk); return err; }