Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754218Ab3JUIwY (ORCPT ); Mon, 21 Oct 2013 04:52:24 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39740 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754183Ab3JUIwU (ORCPT ); Mon, 21 Oct 2013 04:52:20 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Dan Carpenter" , "Daniel Borkmann" , "Neil Horman" , "Michio Honda" , "Vlad Yasevich" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 102/149] net: sctp: fix smatch warning in sctp_send_asconf_del_ip In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2832 Lines: 67 3.2.52-rc1 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: Ben Hutchings --- net/sctp/socket.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ba0108f..c53d01e 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -814,6 +814,9 @@ 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. -- 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/