From patchwork Mon Jun 20 18:19:29 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Whitcroft X-Patchwork-Id: 101175 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 46B96B6F82 for ; Tue, 21 Jun 2011 04:19:43 +1000 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1QYj4S-0005aa-D8; Mon, 20 Jun 2011 18:19:36 +0000 Received: from adelie.canonical.com ([91.189.90.139]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1QYj4Q-0005Zq-6z for kernel-team@lists.ubuntu.com; Mon, 20 Jun 2011 18:19:34 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by adelie.canonical.com with esmtp (Exim 4.71 #1 (Debian)) id 1QYj4Q-0005zx-4P; Mon, 20 Jun 2011 18:19:34 +0000 Received: from 212-139-215-176.dynamic.dsl.as9105.com ([212.139.215.176] helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1QYj4P-0007gv-Tc; Mon, 20 Jun 2011 18:19:34 +0000 From: Andy Whitcroft To: kernel-team@lists.ubuntu.com Subject: [lucid/fsl-imx51 CVE 1/1] sctp: Fix a race between ICMP protocol unreachable and connect() Date: Mon, 20 Jun 2011 19:19:29 +0100 Message-Id: <1308593969-24827-3-git-send-email-apw@canonical.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1308593969-24827-1-git-send-email-apw@canonical.com> References: <1308593969-24827-1-git-send-email-apw@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com From: Vlad Yasevich ICMP protocol unreachable handling completely disregarded the fact that the user may have locked the socket. It proceeded to destroy the association, even though the user may have held the lock and had a ref on the association. This resulted in the following: Attempt to release alive inet socket f6afcc00 ========================= [ BUG: held lock freed! ] ------------------------- somenu/2672 is freeing memory f6afcc00-f6afcfff, with a lock still held there! (sk_lock-AF_INET){+.+.+.}, at: [] sctp_connect+0x13/0x4c 1 lock held by somenu/2672: #0: (sk_lock-AF_INET){+.+.+.}, at: [] sctp_connect+0x13/0x4c stack backtrace: Pid: 2672, comm: somenu Not tainted 2.6.32-telco #55 Call Trace: [] ? printk+0xf/0x11 [] debug_check_no_locks_freed+0xce/0xff [] kmem_cache_free+0x21/0x66 [] __sk_free+0x9d/0xab [] sk_free+0x1c/0x1e [] sctp_association_put+0x32/0x89 [] __sctp_connect+0x36d/0x3f4 [] ? sctp_connect+0x13/0x4c [] ? autoremove_wake_function+0x0/0x33 [] sctp_connect+0x31/0x4c [] inet_dgram_connect+0x4b/0x55 [] sys_connect+0x54/0x71 [] ? lock_release_non_nested+0x88/0x239 [] ? might_fault+0x42/0x7c [] ? might_fault+0x42/0x7c [] sys_socketcall+0x6d/0x178 [] ? trace_hardirqs_on_thunk+0xc/0x10 [] syscall_call+0x7/0xb This was because the sctp_wait_for_connect() would aqcure the socket lock and then proceed to release the last reference count on the association, thus cause the fully destruction path to finish freeing the socket. The simplest solution is to start a very short timer in case the socket is owned by user. When the timer expires, we can do some verification and be able to do the release properly. Signed-off-by: Vlad Yasevich Signed-off-by: David S. Miller (cherry picked from commit 50b5d6ad63821cea324a5a7a19854d4de1a0a819) --- include/net/sctp/sm.h | 1 + include/net/sctp/structs.h | 3 +++ net/sctp/input.c | 22 ++++++++++++++++++---- net/sctp/sm_sideeffect.c | 35 +++++++++++++++++++++++++++++++++++ net/sctp/transport.c | 2 ++ 5 files changed, 59 insertions(+), 4 deletions(-) diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h index c1dd893..76abe6c 100644 --- a/include/net/sctp/sm.h +++ b/include/net/sctp/sm.h @@ -278,6 +278,7 @@ int sctp_do_sm(sctp_event_t event_type, sctp_subtype_t subtype, /* 2nd level prototypes */ void sctp_generate_t3_rtx_event(unsigned long peer); void sctp_generate_heartbeat_event(unsigned long peer); +void sctp_generate_proto_unreach_event(unsigned long peer); void sctp_ootb_pkt_free(struct sctp_packet *); diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h index 3da3a69..a83eee3 100644 --- a/include/net/sctp/structs.h +++ b/include/net/sctp/structs.h @@ -1008,6 +1008,9 @@ struct sctp_transport { /* Heartbeat timer is per destination. */ struct timer_list hb_timer; + /* Timer to handle ICMP proto unreachable envets */ + struct timer_list proto_unreach_timer; + /* Since we're using per-destination retransmission timers * (see above), we're also using per-destination "transmitted" * queues. This probably ought to be a private struct diff --git a/net/sctp/input.c b/net/sctp/input.c index c0c973e..4ffaf57 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -427,11 +427,25 @@ void sctp_icmp_proto_unreachable(struct sock *sk, { SCTP_DEBUG_PRINTK("%s\n", __func__); - sctp_do_sm(SCTP_EVENT_T_OTHER, - SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), - asoc->state, asoc->ep, asoc, t, - GFP_ATOMIC); + if (sock_owned_by_user(sk)) { + if (timer_pending(&t->proto_unreach_timer)) + return; + else { + if (!mod_timer(&t->proto_unreach_timer, + jiffies + (HZ/20))) + sctp_association_hold(asoc); + } + + } else { + if (timer_pending(&t->proto_unreach_timer) && + del_timer(&t->proto_unreach_timer)) + sctp_association_put(asoc); + sctp_do_sm(SCTP_EVENT_T_OTHER, + SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), + asoc->state, asoc->ep, asoc, t, + GFP_ATOMIC); + } } /* Common lookup code for icmp/icmpv6 error handler. */ diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c index 86426aa..25c0131 100644 --- a/net/sctp/sm_sideeffect.c +++ b/net/sctp/sm_sideeffect.c @@ -397,6 +397,41 @@ out_unlock: sctp_transport_put(transport); } +/* Handle the timeout of the ICMP protocol unreachable timer. Trigger + * the correct state machine transition that will close the association. + */ +void sctp_generate_proto_unreach_event(unsigned long data) +{ + struct sctp_transport *transport = (struct sctp_transport *) data; + struct sctp_association *asoc = transport->asoc; + + sctp_bh_lock_sock(asoc->base.sk); + if (sock_owned_by_user(asoc->base.sk)) { + SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __func__); + + /* Try again later. */ + if (!mod_timer(&transport->proto_unreach_timer, + jiffies + (HZ/20))) + sctp_association_hold(asoc); + goto out_unlock; + } + + /* Is this structure just waiting around for us to actually + * get destroyed? + */ + if (asoc->base.dead) + goto out_unlock; + + sctp_do_sm(SCTP_EVENT_T_OTHER, + SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), + asoc->state, asoc->ep, asoc, transport, GFP_ATOMIC); + +out_unlock: + sctp_bh_unlock_sock(asoc->base.sk); + sctp_association_put(asoc); +} + + /* Inject a SACK Timeout event into the state machine. */ static void sctp_generate_sack_event(unsigned long data) { diff --git a/net/sctp/transport.c b/net/sctp/transport.c index e5dde45..8312b56 100644 --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -108,6 +108,8 @@ static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer, (unsigned long)peer); setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event, (unsigned long)peer); + setup_timer(&peer->proto_unreach_timer, + sctp_generate_proto_unreach_event, (unsigned long)peer); /* Initialize the 64-bit random nonce sent with heartbeat. */ get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce));