Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752179AbdFHARm (ORCPT ); Wed, 7 Jun 2017 20:17:42 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:50054 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751812AbdFGXBu (ORCPT ); Wed, 7 Jun 2017 19:01:50 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Philip Pettersson , Eric Dumazet , "David S . Miller" , gregkh@linuxfoundation.org, Willy Tarreau Subject: [PATCH 3.10 001/250] packet: fix race condition in packet_set_ring Date: Thu, 8 Jun 2017 00:56:27 +0200 Message-Id: <1496876436-32402-2-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2815 Lines: 92 From: Philip Pettersson commit 84ac7260236a49c79eede91617700174c2c19b0c upstream. 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 Cc: gregkh@linuxfoundation.org Signed-off-by: Willy Tarreau --- net/packet/af_packet.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 24f0066..e38c699 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3135,19 +3135,25 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv 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: { @@ -3603,6 +3609,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, /* 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)) { WARN(1, "Tx-ring is not supported.\n"); @@ -3684,7 +3691,6 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, goto out; } - lock_sock(sk); /* Detach socket from network */ spin_lock(&po->bind_lock); @@ -3733,11 +3739,11 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, if (!tx_ring) prb_shutdown_retire_blk_timer(po, tx_ring, rb_queue); } - release_sock(sk); if (pg_vec) free_pg_vec(pg_vec, order, req->tp_block_nr); out: + release_sock(sk); return err; } -- 2.8.0.rc2.1.gbe9624a