From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934341AbdKAV24 (ORCPT ); Wed, 1 Nov 2017 17:28:56 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:35424 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933935AbdKAV2y (ORCPT ); Wed, 1 Nov 2017 17:28:54 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Willem de Bruijn , "David S . Miller" , Willy Tarreau Subject: [PATCH 3.10 120/139] packet: fix tp_reserve race in packet_set_ring Date: Wed, 1 Nov 2017 22:26:45 +0100 Message-Id: <1509571624-5001-21-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1509571624-5001-1-git-send-email-w@1wt.eu> References: <1509571159-4405-1-git-send-email-w@1wt.eu> <1509571624-5001-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Willem de Bruijn commit c27927e372f0785f3303e8fad94b85945e2c97b7 upstream. 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: Willy Tarreau --- net/packet/af_packet.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index b915d01..2f22b07 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3183,14 +3183,19 @@ 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; 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: { -- 2.8.0.rc2.1.gbe9624a