<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/net, branch v3.12.32</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>libceph: ceph-msgr workqueue needs a resque worker</title>
<updated>2014-10-31T14:11:32+00:00</updated>
<author>
<name>Ilya Dryomov</name>
<email>idryomov@redhat.com</email>
</author>
<published>2014-10-10T12:39:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=292b588419a9fdd4950ae7944bed6efafa7571ae'/>
<id>292b588419a9fdd4950ae7944bed6efafa7571ae</id>
<content type='text'>
commit f9865f06f7f18c6661c88d0511f05c48612319cc upstream.

Commit f363e45fd118 ("net/ceph: make ceph_msgr_wq non-reentrant")
effectively removed WQ_MEM_RECLAIM flag from ceph_msgr_wq.  This is
wrong - libceph is very much a memory reclaim path, so restore it.

Cc: stable@vger.kernel.org # needs backporting for &lt; 3.12
Signed-off-by: Ilya Dryomov &lt;idryomov@redhat.com&gt;
Tested-by: Micha Krause &lt;micha@krausam.de&gt;
Reviewed-by: Sage Weil &lt;sage@redhat.com&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit f9865f06f7f18c6661c88d0511f05c48612319cc upstream.

Commit f363e45fd118 ("net/ceph: make ceph_msgr_wq non-reentrant")
effectively removed WQ_MEM_RECLAIM flag from ceph_msgr_wq.  This is
wrong - libceph is very much a memory reclaim path, so restore it.

Cc: stable@vger.kernel.org # needs backporting for &lt; 3.12
Signed-off-by: Ilya Dryomov &lt;idryomov@redhat.com&gt;
Tested-by: Micha Krause &lt;micha@krausam.de&gt;
Reviewed-by: Sage Weil &lt;sage@redhat.com&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: fix checksum features handling in netif_skb_features()</title>
<updated>2014-10-31T11:14:36+00:00</updated>
<author>
<name>Michal Kubeček</name>
<email>mkubecek@suse.cz</email>
</author>
<published>2014-08-25T13:16:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=297b3ddd679ac4e4958661df855595bb49c42a18'/>
<id>297b3ddd679ac4e4958661df855595bb49c42a18</id>
<content type='text'>
commit db115037bb57cdfe97078b13da762213f7980e81 upstream.

This is follow-up to

  da08143b8520 ("vlan: more careful checksum features handling")

which introduced more careful feature intersection in vlan code,
taking into account that HW_CSUM should be considered superset
of IP_CSUM/IPV6_CSUM. The same is needed in netif_skb_features()
in order to avoid offloading mismatch warning when vlan is
created on top of a bond consisting of slaves supporting IP/IPv6
checksumming but not vlan Tx offloading.

Signed-off-by: Michal Kubecek &lt;mkubecek@suse.cz&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit db115037bb57cdfe97078b13da762213f7980e81 upstream.

This is follow-up to

  da08143b8520 ("vlan: more careful checksum features handling")

which introduced more careful feature intersection in vlan code,
taking into account that HW_CSUM should be considered superset
of IP_CSUM/IPV6_CSUM. The same is needed in netif_skb_features()
in order to avoid offloading mismatch warning when vlan is
created on top of a bond consisting of slaves supporting IP/IPv6
checksumming but not vlan Tx offloading.

Signed-off-by: Michal Kubecek &lt;mkubecek@suse.cz&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: fixing TLP's FIN recovery</title>
<updated>2014-10-17T07:43:19+00:00</updated>
<author>
<name>Per Hurtig</name>
<email>per.hurtig@kau.se</email>
</author>
<published>2014-06-12T15:08:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d24c1c0f7c31c89465ab1df21bd9fcbe0c6c59ac'/>
<id>d24c1c0f7c31c89465ab1df21bd9fcbe0c6c59ac</id>
<content type='text'>
[ Upstream commit bef1909ee3ed1ca39231b260a8d3b4544ecd0c8f ]

Fix to a problem observed when losing a FIN segment that does not
contain data.  In such situations, TLP is unable to recover from
*any* tail loss and instead adds at least PTO ms to the
retransmission process, i.e., RTO = RTO + PTO.

Signed-off-by: Per Hurtig &lt;per.hurtig@kau.se&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Nandita Dukkipati &lt;nanditad@google.com&gt;
Acked-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit bef1909ee3ed1ca39231b260a8d3b4544ecd0c8f ]

Fix to a problem observed when losing a FIN segment that does not
contain data.  In such situations, TLP is unable to recover from
*any* tail loss and instead adds at least PTO ms to the
retransmission process, i.e., RTO = RTO + PTO.

Signed-off-by: Per Hurtig &lt;per.hurtig@kau.se&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Nandita Dukkipati &lt;nanditad@google.com&gt;
Acked-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sctp: handle association restarts when the socket is closed.</title>
<updated>2014-10-17T07:43:19+00:00</updated>
<author>
<name>Vlad Yasevich</name>
<email>vyasevich@gmail.com</email>
</author>
<published>2014-10-03T22:16:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e6fd6243cdc7434e7001589099394321a1670b47'/>
<id>e6fd6243cdc7434e7001589099394321a1670b47</id>
<content type='text'>
[ Upstream commit bdf6fa52f01b941d4a80372d56de465bdbbd1d23 ]

Currently association restarts do not take into consideration the
state of the socket.  When a restart happens, the current assocation
simply transitions into established state.  This creates a condition
where a remote system, through a the restart procedure, may create a
local association that is no way reachable by user.  The conditions
to trigger this are as follows:
  1) Remote does not acknoledge some data causing data to remain
     outstanding.
  2) Local application calls close() on the socket.  Since data
     is still outstanding, the association is placed in SHUTDOWN_PENDING
     state.  However, the socket is closed.
  3) The remote tries to create a new association, triggering a restart
     on the local system.  The association moves from SHUTDOWN_PENDING
     to ESTABLISHED.  At this point, it is no longer reachable by
     any socket on the local system.

This patch addresses the above situation by moving the newly ESTABLISHED
association into SHUTDOWN-SENT state and bundling a SHUTDOWN after
the COOKIE-ACK chunk.  This way, the restarted associate immidiately
enters the shutdown procedure and forces the termination of the
unreachable association.

Reported-by: David Laight &lt;David.Laight@aculab.com&gt;
Signed-off-by: Vlad Yasevich &lt;vyasevich@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit bdf6fa52f01b941d4a80372d56de465bdbbd1d23 ]

Currently association restarts do not take into consideration the
state of the socket.  When a restart happens, the current assocation
simply transitions into established state.  This creates a condition
where a remote system, through a the restart procedure, may create a
local association that is no way reachable by user.  The conditions
to trigger this are as follows:
  1) Remote does not acknoledge some data causing data to remain
     outstanding.
  2) Local application calls close() on the socket.  Since data
     is still outstanding, the association is placed in SHUTDOWN_PENDING
     state.  However, the socket is closed.
  3) The remote tries to create a new association, triggering a restart
     on the local system.  The association moves from SHUTDOWN_PENDING
     to ESTABLISHED.  At this point, it is no longer reachable by
     any socket on the local system.

This patch addresses the above situation by moving the newly ESTABLISHED
association into SHUTDOWN-SENT state and bundling a SHUTDOWN after
the COOKIE-ACK chunk.  This way, the restarted associate immidiately
enters the shutdown procedure and forces the termination of the
unreachable association.

Reported-by: David Laight &lt;David.Laight@aculab.com&gt;
Signed-off-by: Vlad Yasevich &lt;vyasevich@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ip6_gre: fix flowi6_proto value in xmit path</title>
<updated>2014-10-17T07:43:18+00:00</updated>
<author>
<name>Nicolas Dichtel</name>
<email>nicolas.dichtel@6wind.com</email>
</author>
<published>2014-10-02T16:26:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9865479b5052f0500970ac999c4e9eba41926665'/>
<id>9865479b5052f0500970ac999c4e9eba41926665</id>
<content type='text'>
[ Upstream commit 3be07244b7337760a3269d56b2f4a63e72218648 ]

In xmit path, we build a flowi6 which will be used for the output route lookup.
We are sending a GRE packet, neither IPv4 nor IPv6 encapsulated packet, thus the
protocol should be IPPROTO_GRE.

Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
Reported-by: Matthieu Ternisien d'Ouville &lt;matthieu.tdo@6wind.com&gt;
Signed-off-by: Nicolas Dichtel &lt;nicolas.dichtel@6wind.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3be07244b7337760a3269d56b2f4a63e72218648 ]

In xmit path, we build a flowi6 which will be used for the output route lookup.
We are sending a GRE packet, neither IPv4 nor IPv6 encapsulated packet, thus the
protocol should be IPPROTO_GRE.

Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
Reported-by: Matthieu Ternisien d'Ouville &lt;matthieu.tdo@6wind.com&gt;
Signed-off-by: Nicolas Dichtel &lt;nicolas.dichtel@6wind.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xfrm: Generate queueing routes only from route lookup functions</title>
<updated>2014-10-17T07:43:16+00:00</updated>
<author>
<name>Steffen Klassert</name>
<email>steffen.klassert@secunet.com</email>
</author>
<published>2014-09-16T08:08:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2a9e5d6b68e0d88843caeeb69944e17c632f8a73'/>
<id>2a9e5d6b68e0d88843caeeb69944e17c632f8a73</id>
<content type='text'>
[ Upstream commit b8c203b2d2fc961bafd53b41d5396bbcdec55998 ]

Currently we genarate a queueing route if we have matching policies
but can not resolve the states and the sysctl xfrm_larval_drop is
disabled. Here we assume that dst_output() is called to kill the
queued packets. Unfortunately this assumption is not true in all
cases, so it is possible that these packets leave the system unwanted.

We fix this by generating queueing routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: a0073fe18e71 ("xfrm: Add a state resolution packet queue")
Reported-by: Konstantinos Kolelis &lt;k.kolelis@sirrix.com&gt;
Signed-off-by: Steffen Klassert &lt;steffen.klassert@secunet.com&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b8c203b2d2fc961bafd53b41d5396bbcdec55998 ]

Currently we genarate a queueing route if we have matching policies
but can not resolve the states and the sysctl xfrm_larval_drop is
disabled. Here we assume that dst_output() is called to kill the
queued packets. Unfortunately this assumption is not true in all
cases, so it is possible that these packets leave the system unwanted.

We fix this by generating queueing routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: a0073fe18e71 ("xfrm: Add a state resolution packet queue")
Reported-by: Konstantinos Kolelis &lt;k.kolelis@sirrix.com&gt;
Signed-off-by: Steffen Klassert &lt;steffen.klassert@secunet.com&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xfrm: Generate blackhole routes only from route lookup functions</title>
<updated>2014-10-17T07:43:16+00:00</updated>
<author>
<name>Steffen Klassert</name>
<email>steffen.klassert@secunet.com</email>
</author>
<published>2014-09-16T08:08:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e5a51bbc5bacc7131a8ff04412468a0517dbb2b2'/>
<id>e5a51bbc5bacc7131a8ff04412468a0517dbb2b2</id>
<content type='text'>
[ Upstream commit f92ee61982d6da15a9e49664ecd6405a15a2ee56 ]

Currently we genarate a blackhole route route whenever we have
matching policies but can not resolve the states. Here we assume
that dst_output() is called to kill the balckholed packets.
Unfortunately this assumption is not true in all cases, so
it is possible that these packets leave the system unwanted.

We fix this by generating blackhole routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: 2774c131b1d ("xfrm: Handle blackhole route creation via afinfo.")
Reported-by: Konstantinos Kolelis &lt;k.kolelis@sirrix.com&gt;
Signed-off-by: Steffen Klassert &lt;steffen.klassert@secunet.com&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit f92ee61982d6da15a9e49664ecd6405a15a2ee56 ]

Currently we genarate a blackhole route route whenever we have
matching policies but can not resolve the states. Here we assume
that dst_output() is called to kill the balckholed packets.
Unfortunately this assumption is not true in all cases, so
it is possible that these packets leave the system unwanted.

We fix this by generating blackhole routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: 2774c131b1d ("xfrm: Handle blackhole route creation via afinfo.")
Reported-by: Konstantinos Kolelis &lt;k.kolelis@sirrix.com&gt;
Signed-off-by: Steffen Klassert &lt;steffen.klassert@secunet.com&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bridge: Fix br_should_learn to check vlan_enabled</title>
<updated>2014-10-17T07:43:14+00:00</updated>
<author>
<name>Vlad Yasevich</name>
<email>vyasevich@gmail.com</email>
</author>
<published>2014-09-15T19:24:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=77bd83323c2423d2f42bacc2140923860e269af9'/>
<id>77bd83323c2423d2f42bacc2140923860e269af9</id>
<content type='text'>
[ Upstream commit c095f248e63ada504dd90c90baae673ae10ee3fe ]

As Toshiaki Makita pointed out, the BRIDGE_INPUT_SKB_CB will
not be initialized in br_should_learn() as that function
is called only from br_handle_local_finish().  That is
an input handler for link-local ethernet traffic so it perfectly
correct to check br-&gt;vlan_enabled here.

Reported-by: Toshiaki Makita&lt;toshiaki.makita1@gmail.com&gt;
Fixes: 20adfa1 bridge: Check if vlan filtering is enabled only once.
Signed-off-by: Vladislav Yasevich &lt;vyasevic@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit c095f248e63ada504dd90c90baae673ae10ee3fe ]

As Toshiaki Makita pointed out, the BRIDGE_INPUT_SKB_CB will
not be initialized in br_should_learn() as that function
is called only from br_handle_local_finish().  That is
an input handler for link-local ethernet traffic so it perfectly
correct to check br-&gt;vlan_enabled here.

Reported-by: Toshiaki Makita&lt;toshiaki.makita1@gmail.com&gt;
Fixes: 20adfa1 bridge: Check if vlan filtering is enabled only once.
Signed-off-by: Vladislav Yasevich &lt;vyasevic@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bridge: Check if vlan filtering is enabled only once.</title>
<updated>2014-10-17T07:43:14+00:00</updated>
<author>
<name>Vlad Yasevich</name>
<email>vyasevich@gmail.com</email>
</author>
<published>2014-09-12T20:26:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6266beeee8158338a894b2ab3a477424e9631696'/>
<id>6266beeee8158338a894b2ab3a477424e9631696</id>
<content type='text'>
[ Upstream commit 20adfa1a81af00bf2027644507ad4fa9cd2849cf ]

The bridge code checks if vlan filtering is enabled on both
ingress and egress.   When the state flip happens, it
is possible for the bridge to currently be forwarding packets
and forwarding behavior becomes non-deterministic.  Bridge
may drop packets on some interfaces, but not others.

This patch solves this by caching the filtered state of the
packet into skb_cb on ingress.  The skb_cb is guaranteed to
not be over-written between the time packet entres bridge
forwarding path and the time it leaves it.  On egress, we
can then check the cached state to see if we need to
apply filtering information.

Signed-off-by: Vladislav Yasevich &lt;vyasevic@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 20adfa1a81af00bf2027644507ad4fa9cd2849cf ]

The bridge code checks if vlan filtering is enabled on both
ingress and egress.   When the state flip happens, it
is possible for the bridge to currently be forwarding packets
and forwarding behavior becomes non-deterministic.  Bridge
may drop packets on some interfaces, but not others.

This patch solves this by caching the filtered state of the
packet into skb_cb on ingress.  The skb_cb is guaranteed to
not be over-written between the time packet entres bridge
forwarding path and the time it leaves it.  On egress, we
can then check the cached state to see if we need to
apply filtering information.

Signed-off-by: Vladislav Yasevich &lt;vyasevic@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>l2tp: fix race while getting PMTU on PPP pseudo-wire</title>
<updated>2014-10-17T07:43:14+00:00</updated>
<author>
<name>Guillaume Nault</name>
<email>g.nault@alphalink.fr</email>
</author>
<published>2014-09-03T12:12:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=048b4e83910547178851bef4c47cf40d015ad9eb'/>
<id>048b4e83910547178851bef4c47cf40d015ad9eb</id>
<content type='text'>
[ Upstream commit eed4d839b0cdf9d84b0a9bc63de90fd5e1e886fb ]

Use dst_entry held by sk_dst_get() to retrieve tunnel's PMTU.

The dst_mtu(__sk_dst_get(tunnel-&gt;sock)) call was racy. __sk_dst_get()
could return NULL if tunnel-&gt;sock-&gt;sk_dst_cache was reset just before the
call, thus making dst_mtu() dereference a NULL pointer:

[ 1937.661598] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
[ 1937.664005] IP: [&lt;ffffffffa049db88&gt;] pppol2tp_connect+0x33d/0x41e [l2tp_ppp]
[ 1937.664005] PGD daf0c067 PUD d9f93067 PMD 0
[ 1937.664005] Oops: 0000 [#1] SMP
[ 1937.664005] Modules linked in: l2tp_ppp l2tp_netlink l2tp_core ip6table_filter ip6_tables iptable_filter ip_tables ebtable_nat ebtables x_tables udp_tunnel pppoe pppox ppp_generic slhc deflate ctr twofish_generic twofish_x86_64_3way xts lrw gf128mul glue_helper twofish_x86_64 twofish_common blowfish_generic blowfish_x86_64 blowfish_common des_generic cbc xcbc rmd160 sha512_generic hmac crypto_null af_key xfrm_algo 8021q garp bridge stp llc tun atmtcp clip atm ext3 mbcache jbd iTCO_wdt coretemp kvm_intel iTCO_vendor_support kvm pcspkr evdev ehci_pci lpc_ich mfd_core i5400_edac edac_core i5k_amb shpchp button processor thermal_sys xfs crc32c_generic libcrc32c dm_mod usbhid sg hid sr_mod sd_mod cdrom crc_t10dif crct10dif_common ata_generic ahci ata_piix tg3 libahci libata uhci_hcd ptp ehci_hcd pps_core usbcore scsi_mod libphy usb_common [last unloaded: l2tp_core]
[ 1937.664005] CPU: 0 PID: 10022 Comm: l2tpstress Tainted: G           O   3.17.0-rc1 #1
[ 1937.664005] Hardware name: HP ProLiant DL160 G5, BIOS O12 08/22/2008
[ 1937.664005] task: ffff8800d8fda790 ti: ffff8800c43c4000 task.ti: ffff8800c43c4000
[ 1937.664005] RIP: 0010:[&lt;ffffffffa049db88&gt;]  [&lt;ffffffffa049db88&gt;] pppol2tp_connect+0x33d/0x41e [l2tp_ppp]
[ 1937.664005] RSP: 0018:ffff8800c43c7de8  EFLAGS: 00010282
[ 1937.664005] RAX: ffff8800da8a7240 RBX: ffff8800d8c64600 RCX: 000001c325a137b5
[ 1937.664005] RDX: 8c6318c6318c6320 RSI: 000000000000010c RDI: 0000000000000000
[ 1937.664005] RBP: ffff8800c43c7ea8 R08: 0000000000000000 R09: 0000000000000000
[ 1937.664005] R10: ffffffffa048e2c0 R11: ffff8800d8c64600 R12: ffff8800ca7a5000
[ 1937.664005] R13: ffff8800c439bf40 R14: 000000000000000c R15: 0000000000000009
[ 1937.664005] FS:  00007fd7f610f700(0000) GS:ffff88011a600000(0000) knlGS:0000000000000000
[ 1937.664005] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 1937.664005] CR2: 0000000000000020 CR3: 00000000d9d75000 CR4: 00000000000027e0
[ 1937.664005] Stack:
[ 1937.664005]  ffffffffa049da80 ffff8800d8fda790 000000000000005b ffff880000000009
[ 1937.664005]  ffff8800daf3f200 0000000000000003 ffff8800c43c7e48 ffffffff81109b57
[ 1937.664005]  ffffffff81109b0e ffffffff8114c566 0000000000000000 0000000000000000
[ 1937.664005] Call Trace:
[ 1937.664005]  [&lt;ffffffffa049da80&gt;] ? pppol2tp_connect+0x235/0x41e [l2tp_ppp]
[ 1937.664005]  [&lt;ffffffff81109b57&gt;] ? might_fault+0x9e/0xa5
[ 1937.664005]  [&lt;ffffffff81109b0e&gt;] ? might_fault+0x55/0xa5
[ 1937.664005]  [&lt;ffffffff8114c566&gt;] ? rcu_read_unlock+0x1c/0x26
[ 1937.664005]  [&lt;ffffffff81309196&gt;] SYSC_connect+0x87/0xb1
[ 1937.664005]  [&lt;ffffffff813e56f7&gt;] ? sysret_check+0x1b/0x56
[ 1937.664005]  [&lt;ffffffff8107590d&gt;] ? trace_hardirqs_on_caller+0x145/0x1a1
[ 1937.664005]  [&lt;ffffffff81213dee&gt;] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 1937.664005]  [&lt;ffffffff8114c262&gt;] ? spin_lock+0x9/0xb
[ 1937.664005]  [&lt;ffffffff813092b4&gt;] SyS_connect+0x9/0xb
[ 1937.664005]  [&lt;ffffffff813e56d2&gt;] system_call_fastpath+0x16/0x1b
[ 1937.664005] Code: 10 2a 84 81 e8 65 76 bd e0 65 ff 0c 25 10 bb 00 00 4d 85 ed 74 37 48 8b 85 60 ff ff ff 48 8b 80 88 01 00 00 48 8b b8 10 02 00 00 &lt;48&gt; 8b 47 20 ff 50 20 85 c0 74 0f 83 e8 28 89 83 10 01 00 00 89
[ 1937.664005] RIP  [&lt;ffffffffa049db88&gt;] pppol2tp_connect+0x33d/0x41e [l2tp_ppp]
[ 1937.664005]  RSP &lt;ffff8800c43c7de8&gt;
[ 1937.664005] CR2: 0000000000000020
[ 1939.559375] ---[ end trace 82d44500f28f8708 ]---

Fixes: f34c4a35d879 ("l2tp: take PMTU from tunnel UDP socket")
Signed-off-by: Guillaume Nault &lt;g.nault@alphalink.fr&gt;
Acked-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
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[ Upstream commit eed4d839b0cdf9d84b0a9bc63de90fd5e1e886fb ]

Use dst_entry held by sk_dst_get() to retrieve tunnel's PMTU.

The dst_mtu(__sk_dst_get(tunnel-&gt;sock)) call was racy. __sk_dst_get()
could return NULL if tunnel-&gt;sock-&gt;sk_dst_cache was reset just before the
call, thus making dst_mtu() dereference a NULL pointer:

[ 1937.661598] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
[ 1937.664005] IP: [&lt;ffffffffa049db88&gt;] pppol2tp_connect+0x33d/0x41e [l2tp_ppp]
[ 1937.664005] PGD daf0c067 PUD d9f93067 PMD 0
[ 1937.664005] Oops: 0000 [#1] SMP
[ 1937.664005] Modules linked in: l2tp_ppp l2tp_netlink l2tp_core ip6table_filter ip6_tables iptable_filter ip_tables ebtable_nat ebtables x_tables udp_tunnel pppoe pppox ppp_generic slhc deflate ctr twofish_generic twofish_x86_64_3way xts lrw gf128mul glue_helper twofish_x86_64 twofish_common blowfish_generic blowfish_x86_64 blowfish_common des_generic cbc xcbc rmd160 sha512_generic hmac crypto_null af_key xfrm_algo 8021q garp bridge stp llc tun atmtcp clip atm ext3 mbcache jbd iTCO_wdt coretemp kvm_intel iTCO_vendor_support kvm pcspkr evdev ehci_pci lpc_ich mfd_core i5400_edac edac_core i5k_amb shpchp button processor thermal_sys xfs crc32c_generic libcrc32c dm_mod usbhid sg hid sr_mod sd_mod cdrom crc_t10dif crct10dif_common ata_generic ahci ata_piix tg3 libahci libata uhci_hcd ptp ehci_hcd pps_core usbcore scsi_mod libphy usb_common [last unloaded: l2tp_core]
[ 1937.664005] CPU: 0 PID: 10022 Comm: l2tpstress Tainted: G           O   3.17.0-rc1 #1
[ 1937.664005] Hardware name: HP ProLiant DL160 G5, BIOS O12 08/22/2008
[ 1937.664005] task: ffff8800d8fda790 ti: ffff8800c43c4000 task.ti: ffff8800c43c4000
[ 1937.664005] RIP: 0010:[&lt;ffffffffa049db88&gt;]  [&lt;ffffffffa049db88&gt;] pppol2tp_connect+0x33d/0x41e [l2tp_ppp]
[ 1937.664005] RSP: 0018:ffff8800c43c7de8  EFLAGS: 00010282
[ 1937.664005] RAX: ffff8800da8a7240 RBX: ffff8800d8c64600 RCX: 000001c325a137b5
[ 1937.664005] RDX: 8c6318c6318c6320 RSI: 000000000000010c RDI: 0000000000000000
[ 1937.664005] RBP: ffff8800c43c7ea8 R08: 0000000000000000 R09: 0000000000000000
[ 1937.664005] R10: ffffffffa048e2c0 R11: ffff8800d8c64600 R12: ffff8800ca7a5000
[ 1937.664005] R13: ffff8800c439bf40 R14: 000000000000000c R15: 0000000000000009
[ 1937.664005] FS:  00007fd7f610f700(0000) GS:ffff88011a600000(0000) knlGS:0000000000000000
[ 1937.664005] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 1937.664005] CR2: 0000000000000020 CR3: 00000000d9d75000 CR4: 00000000000027e0
[ 1937.664005] Stack:
[ 1937.664005]  ffffffffa049da80 ffff8800d8fda790 000000000000005b ffff880000000009
[ 1937.664005]  ffff8800daf3f200 0000000000000003 ffff8800c43c7e48 ffffffff81109b57
[ 1937.664005]  ffffffff81109b0e ffffffff8114c566 0000000000000000 0000000000000000
[ 1937.664005] Call Trace:
[ 1937.664005]  [&lt;ffffffffa049da80&gt;] ? pppol2tp_connect+0x235/0x41e [l2tp_ppp]
[ 1937.664005]  [&lt;ffffffff81109b57&gt;] ? might_fault+0x9e/0xa5
[ 1937.664005]  [&lt;ffffffff81109b0e&gt;] ? might_fault+0x55/0xa5
[ 1937.664005]  [&lt;ffffffff8114c566&gt;] ? rcu_read_unlock+0x1c/0x26
[ 1937.664005]  [&lt;ffffffff81309196&gt;] SYSC_connect+0x87/0xb1
[ 1937.664005]  [&lt;ffffffff813e56f7&gt;] ? sysret_check+0x1b/0x56
[ 1937.664005]  [&lt;ffffffff8107590d&gt;] ? trace_hardirqs_on_caller+0x145/0x1a1
[ 1937.664005]  [&lt;ffffffff81213dee&gt;] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 1937.664005]  [&lt;ffffffff8114c262&gt;] ? spin_lock+0x9/0xb
[ 1937.664005]  [&lt;ffffffff813092b4&gt;] SyS_connect+0x9/0xb
[ 1937.664005]  [&lt;ffffffff813e56d2&gt;] system_call_fastpath+0x16/0x1b
[ 1937.664005] Code: 10 2a 84 81 e8 65 76 bd e0 65 ff 0c 25 10 bb 00 00 4d 85 ed 74 37 48 8b 85 60 ff ff ff 48 8b 80 88 01 00 00 48 8b b8 10 02 00 00 &lt;48&gt; 8b 47 20 ff 50 20 85 c0 74 0f 83 e8 28 89 83 10 01 00 00 89
[ 1937.664005] RIP  [&lt;ffffffffa049db88&gt;] pppol2tp_connect+0x33d/0x41e [l2tp_ppp]
[ 1937.664005]  RSP &lt;ffff8800c43c7de8&gt;
[ 1937.664005] CR2: 0000000000000020
[ 1939.559375] ---[ end trace 82d44500f28f8708 ]---

Fixes: f34c4a35d879 ("l2tp: take PMTU from tunnel UDP socket")
Signed-off-by: Guillaume Nault &lt;g.nault@alphalink.fr&gt;
Acked-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
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