Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754302AbbLLUdw (ORCPT ); Sat, 12 Dec 2015 15:33:52 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38585 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753264AbbLLU0q (ORCPT ); Sat, 12 Dec 2015 15:26:46 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "David S. Miller" , Vegard Nossum , Sasha Levin , Santosh Shilimkar , Quentin Casasnovas Subject: [PATCH 4.3 38/71] RDS: fix race condition when sending a message on unbound socket Date: Sat, 12 Dec 2015 12:06:02 -0800 Message-Id: <20151212200538.665963602@linuxfoundation.org> X-Mailer: git-send-email 2.6.4 In-Reply-To: <20151212200536.761001328@linuxfoundation.org> References: <20151212200536.761001328@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2537 Lines: 79 4.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Quentin Casasnovas [ Upstream commit 8c7188b23474cca017b3ef354c4a58456f68303a ] Sasha's found a NULL pointer dereference in the RDS connection code when sending a message to an apparently unbound socket. The problem is caused by the code checking if the socket is bound in rds_sendmsg(), which checks the rs_bound_addr field without taking a lock on the socket. This opens a race where rs_bound_addr is temporarily set but where the transport is not in rds_bind(), leading to a NULL pointer dereference when trying to dereference 'trans' in __rds_conn_create(). Vegard wrote a reproducer for this issue, so kindly ask him to share if you're interested. I cannot reproduce the NULL pointer dereference using Vegard's reproducer with this patch, whereas I could without. Complete earlier incomplete fix to CVE-2015-6937: 74e98eb08588 ("RDS: verify the underlying transport exists before creating a connection") Cc: David S. Miller Cc: stable@vger.kernel.org Reviewed-by: Vegard Nossum Reviewed-by: Sasha Levin Acked-by: Santosh Shilimkar Signed-off-by: Quentin Casasnovas Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/rds/connection.c | 6 ------ net/rds/send.c | 4 +++- 2 files changed, 3 insertions(+), 7 deletions(-) --- a/net/rds/connection.c +++ b/net/rds/connection.c @@ -190,12 +190,6 @@ new_conn: } } - if (trans == NULL) { - kmem_cache_free(rds_conn_slab, conn); - conn = ERR_PTR(-ENODEV); - goto out; - } - conn->c_trans = trans; ret = trans->conn_alloc(conn, gfp); --- a/net/rds/send.c +++ b/net/rds/send.c @@ -1009,11 +1009,13 @@ int rds_sendmsg(struct socket *sock, str release_sock(sk); } - /* racing with another thread binding seems ok here */ + lock_sock(sk); if (daddr == 0 || rs->rs_bound_addr == 0) { + release_sock(sk); ret = -ENOTCONN; /* XXX not a great errno */ goto out; } + release_sock(sk); if (payload_len > rds_sk_sndbuf(rs)) { ret = -EMSGSIZE; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/