sctp: Fix a race between ICMP protocol unreachable and connect()

commit 50b5d6ad63821cea324a5a7a19854d4de1a0a819 upstream.

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: [<c122098a>] sctp_connect+0x13/0x4c
1 lock held by somenu/2672:
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c

stack backtrace:
Pid: 2672, comm: somenu Not tainted 2.6.32-telco #55
Call Trace:
 [<c1232266>] ? printk+0xf/0x11
 [<c1038553>] debug_check_no_locks_freed+0xce/0xff
 [<c10620b4>] kmem_cache_free+0x21/0x66
 [<c1185f25>] __sk_free+0x9d/0xab
 [<c1185f9c>] sk_free+0x1c/0x1e
 [<c1216e38>] sctp_association_put+0x32/0x89
 [<c1220865>] __sctp_connect+0x36d/0x3f4
 [<c122098a>] ? sctp_connect+0x13/0x4c
 [<c102d073>] ? autoremove_wake_function+0x0/0x33
 [<c12209a8>] sctp_connect+0x31/0x4c
 [<c11d1e80>] inet_dgram_connect+0x4b/0x55
 [<c11834fa>] sys_connect+0x54/0x71
 [<c103a3a2>] ? lock_release_non_nested+0x88/0x239
 [<c1054026>] ? might_fault+0x42/0x7c
 [<c1054026>] ? might_fault+0x42/0x7c
 [<c11847ab>] sys_socketcall+0x6d/0x178
 [<c10da994>] ? trace_hardirqs_on_thunk+0xc/0x10
 [<c1002959>] 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 <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index c1dd893658331eef66f580bdf34c20aebabe385c..76abe6cb7e2f3af9badac8cc0c32453741603232 100644 (file)
--- 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 89e54e932368430bcabad6f2210a6c510428ef4e..88daa54eeef8a35e46bd486d58a2fd9f2e44c6b3 100644 (file)
--- 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 c0c973e67addd236fa438aca6ca84d3058495ebd..254afea4c1afd2ca589162d6333db32e26a596b5 100644 (file)
--- 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 efa516b47e816b43bf8e6ad974f8dc5cc16d9ad9..306bb8b07a514768e1e1286a7258943e1dedf9cb 100644 (file)
--- 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 37a1184d789f7fe90408120fef731e76ed6088c4..e04c9f844abf1a75351a54c57402014cc61b99e1 100644 (file)
--- 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));