From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755788Ab3J2STP (ORCPT ); Tue, 29 Oct 2013 14:19:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:59471 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754093Ab3J2SJG (ORCPT ); Tue, 29 Oct 2013 14:09:06 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Neil Horman , Daniel Borkmann , Michio Honda , "David S. Miller" , Kamal Mostafa Subject: [PATCH 3.8 32/81] net: sctp: fix smatch warning in sctp_send_asconf_del_ip Date: Tue, 29 Oct 2013 11:03:53 -0700 Message-Id: <1383069882-11437-33-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1383069882-11437-1-git-send-email-kamal@canonical.com> References: <1383069882-11437-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 88362ad8f9a6cea787420b57cc27ccacef000dbe ] This was originally reported in [1] and posted by Neil Horman [2], he said: Fix up a missed null pointer check in the asconf code. If we don't find a local address, but we pass in an address length of more than 1, we may dereference a NULL laddr pointer. Currently this can't happen, as the only users of the function pass in the value 1 as the addrcnt parameter, but its not hot path, and it doesn't hurt to check for NULL should that ever be the case. The callpath from sctp_asconf_mgmt() looks okay. But this could be triggered from sctp_setsockopt_bindx() call with SCTP_BINDX_REM_ADDR and addrcnt > 1 while passing all possible addresses from the bind list to SCTP_BINDX_REM_ADDR so that we do *not* find a single address in the association's bind address list that is not in the packed array of addresses. If this happens when we have an established association with ASCONF-capable peers, then we could get a NULL pointer dereference as we only check for laddr == NULL && addrcnt == 1 and call later sctp_make_asconf_update_ip() with NULL laddr. BUT: this actually won't happen as sctp_bindx_rem() will catch such a case and return with an error earlier. As this is incredably unintuitive and error prone, add a check to catch at least future bugs here. As Neil says, its not hot path. Introduced by 8a07eb0a5 ("sctp: Add ASCONF operation on the single-homed host"). [1] http://www.spinics.net/lists/linux-sctp/msg02132.html [2] http://www.spinics.net/lists/linux-sctp/msg02133.html Reported-by: Dan Carpenter Signed-off-by: Neil Horman Signed-off-by: Daniel Borkmann Cc: Michio Honda Acked-By: Neil Horman Acked-by: Vlad Yasevich Signed-off-by: David S. Miller Signed-off-by: Kamal Mostafa --- net/sctp/socket.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ea5c61a..89714ee 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -820,6 +820,9 @@ static int sctp_send_asconf_del_ip(struct sock *sk, goto skip_mkasconf; } + if (laddr == NULL) + return -EINVAL; + /* We do not need RCU protection throughout this loop * because this is done under a socket lock from the * setsockopt call. -- 1.8.1.2