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authorVlad Yasevich <vladislav.yasevich@hp.com>2010-05-06 00:56:07 -0700
committerDavid S. Miller <davem@davemloft.net>2010-05-06 00:56:07 -0700
commit50b5d6ad63821cea324a5a7a19854d4de1a0a819 (patch)
treea279d53880e3bdf144783598ad03bbaa33e2cd96 /net
parent6ec82562ffc6f297d0de36d65776cff8e5704867 (diff)
downloadlinux-2.6.34-ux500-50b5d6ad63821cea324a5a7a19854d4de1a0a819.tar.gz
sctp: Fix a race between ICMP protocol unreachable and connect()
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>
Diffstat (limited to 'net')
-rw-r--r--net/sctp/input.c22
-rw-r--r--net/sctp/sm_sideeffect.c35
-rw-r--r--net/sctp/transport.c2
3 files changed, 55 insertions, 4 deletions
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 2a570184e5a..ea2192444ce 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -440,11 +440,25 @@ 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 d5ae450b6f0..eb1f42f45fd 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 be4d63d5a5c..4a368038d46 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));