linux-stable.git/net/l2tp, branch v3.2.99 Linux kernel stable tree l2tp: initialise PPP sessions before registering them 2018-02-13T18:32:12+00:00 Guillaume Nault g.nault@alphalink.fr 2017-10-27T14:51:52+00:00 36a4db64f7d6e43c3d38f7e1430c4288d21c6dd9 commit f98be6c6359e7e4a61aaefb9964c1db31cb9ec0c upstream. pppol2tp_connect() initialises L2TP sessions after they've been exposed to the rest of the system by l2tp_session_register(). This puts sessions into transient states that are the source of several races, in particular with session's deletion path. This patch centralises the initialisation code into pppol2tp_session_init(), which is called before the registration phase. The only field that can't be set before session registration is the pppol2tp socket pointer, which has already been converted to RCU. So pppol2tp_connect() should now be race-free. The session's .session_close() callback is now set before registration. Therefore, it's always called when l2tp_core deletes the session, even if it was created by pppol2tp_session_create() and hasn't been plugged to a pppol2tp socket yet. That'd prevent session free because the extra reference taken by pppol2tp_session_close() wouldn't be dropped by the socket's ->sk_destruct() callback (pppol2tp_session_destruct()). We could set .session_close() only while connecting a session to its pppol2tp socket, or teach pppol2tp_session_close() to avoid grabbing a reference when the session isn't connected, but that'd require adding some form of synchronisation to be race free. Instead of that, we can just let the pppol2tp socket hold a reference on the session as soon as it starts depending on it (that is, in pppol2tp_connect()). Then we don't need to utilise pppol2tp_session_close() to hold a reference at the last moment to prevent l2tp_core from dropping it. When releasing the socket, pppol2tp_release() now deletes the session using the standard l2tp_session_delete() function, instead of merely removing it from hash tables. l2tp_session_delete() drops the reference the sessions holds on itself, but also makes sure it doesn't remove a session twice. So it can safely be called, even if l2tp_core already tried, or is concurrently trying, to remove the session. Finally, pppol2tp_session_destruct() drops the reference held by the socket. Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit f98be6c6359e7e4a61aaefb9964c1db31cb9ec0c upstream.

pppol2tp_connect() initialises L2TP sessions after they've been exposed
to the rest of the system by l2tp_session_register(). This puts
sessions into transient states that are the source of several races, in
particular with session's deletion path.

This patch centralises the initialisation code into
pppol2tp_session_init(), which is called before the registration phase.
The only field that can't be set before session registration is the
pppol2tp socket pointer, which has already been converted to RCU. So
pppol2tp_connect() should now be race-free.

The session's .session_close() callback is now set before registration.
Therefore, it's always called when l2tp_core deletes the session, even
if it was created by pppol2tp_session_create() and hasn't been plugged
to a pppol2tp socket yet. That'd prevent session free because the extra
reference taken by pppol2tp_session_close() wouldn't be dropped by the
socket's ->sk_destruct() callback (pppol2tp_session_destruct()).
We could set .session_close() only while connecting a session to its
pppol2tp socket, or teach pppol2tp_session_close() to avoid grabbing a
reference when the session isn't connected, but that'd require adding
some form of synchronisation to be race free.

Instead of that, we can just let the pppol2tp socket hold a reference
on the session as soon as it starts depending on it (that is, in
pppol2tp_connect()). Then we don't need to utilise
pppol2tp_session_close() to hold a reference at the last moment to
prevent l2tp_core from dropping it.

When releasing the socket, pppol2tp_release() now deletes the session
using the standard l2tp_session_delete() function, instead of merely
removing it from hash tables. l2tp_session_delete() drops the reference
the sessions holds on itself, but also makes sure it doesn't remove a
session twice. So it can safely be called, even if l2tp_core already
tried, or is concurrently trying, to remove the session.
Finally, pppol2tp_session_destruct() drops the reference held by the
socket.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: protect sock pointer of struct pppol2tp_session with RCU 2018-02-13T18:32:12+00:00 Guillaume Nault g.nault@alphalink.fr 2017-10-27T14:51:52+00:00 d36e5ba7bbed5d7bd26e8609ffed503c2def401b commit ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 upstream. pppol2tp_session_create() registers sessions that can't have their corresponding socket initialised. This socket has to be created by userspace, then connected to the session by pppol2tp_connect(). Therefore, we need to protect the pppol2tp socket pointer of L2TP sessions, so that it can safely be updated when userspace is connecting or closing the socket. This will eventually allow pppol2tp_connect() to avoid generating transient states while initialising its parts of the session. To this end, this patch protects the pppol2tp socket pointer using RCU. The pppol2tp socket pointer is still set in pppol2tp_connect(), but only once we know the function isn't going to fail. It's eventually reset by pppol2tp_release(), which now has to wait for a grace period to elapse before it can drop the last reference on the socket. This ensures that pppol2tp_session_get_sock() can safely grab a reference on the socket, even after ps->sk is reset to NULL but before this operation actually gets visible from pppol2tp_session_get_sock(). The rest is standard RCU conversion: pppol2tp_recv(), which already runs in atomic context, is simply enclosed by rcu_read_lock() and rcu_read_unlock(), while other functions are converted to use pppol2tp_session_get_sock() followed by sock_put(). pppol2tp_session_setsockopt() is a special case. It used to retrieve the pppol2tp socket from the L2TP session, which itself was retrieved from the pppol2tp socket. Therefore we can just avoid dereferencing ps->sk and directly use the original socket pointer instead. With all users of ps->sk now handling NULL and concurrent updates, the L2TP ->ref() and ->deref() callbacks aren't needed anymore. Therefore, rather than converting pppol2tp_session_sock_hold() and pppol2tp_session_sock_put(), we can just drop them. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 upstream.

pppol2tp_session_create() registers sessions that can't have their
corresponding socket initialised. This socket has to be created by
userspace, then connected to the session by pppol2tp_connect().
Therefore, we need to protect the pppol2tp socket pointer of L2TP
sessions, so that it can safely be updated when userspace is connecting
or closing the socket. This will eventually allow pppol2tp_connect()
to avoid generating transient states while initialising its parts of the
session.

To this end, this patch protects the pppol2tp socket pointer using RCU.

The pppol2tp socket pointer is still set in pppol2tp_connect(), but
only once we know the function isn't going to fail. It's eventually
reset by pppol2tp_release(), which now has to wait for a grace period
to elapse before it can drop the last reference on the socket. This
ensures that pppol2tp_session_get_sock() can safely grab a reference
on the socket, even after ps->sk is reset to NULL but before this
operation actually gets visible from pppol2tp_session_get_sock().

The rest is standard RCU conversion: pppol2tp_recv(), which already
runs in atomic context, is simply enclosed by rcu_read_lock() and
rcu_read_unlock(), while other functions are converted to use
pppol2tp_session_get_sock() followed by sock_put().
pppol2tp_session_setsockopt() is a special case. It used to retrieve
the pppol2tp socket from the L2TP session, which itself was retrieved
from the pppol2tp socket. Therefore we can just avoid dereferencing
ps->sk and directly use the original socket pointer instead.

With all users of ps->sk now handling NULL and concurrent updates, the
L2TP ->ref() and ->deref() callbacks aren't needed anymore. Therefore,
rather than converting pppol2tp_session_sock_hold() and
pppol2tp_session_sock_put(), we can just drop them.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: initialise l2tp_eth sessions before registering them 2018-02-13T18:32:11+00:00 Guillaume Nault g.nault@alphalink.fr 2017-10-27T14:51:51+00:00 b10888191e844a945887f72db3f8a2e75ced6b63 commit ee28de6bbd78c2e18111a0aef43ea746f28d2073 upstream. Sessions must be initialised before being made externally visible by l2tp_session_register(). Otherwise the session may be concurrently deleted before being initialised, which can confuse the deletion path and eventually lead to kernel oops. Therefore, we need to move l2tp_session_register() down in l2tp_eth_create(), but also handle the intermediate step where only the session or the netdevice has been registered. We can't just call l2tp_session_register() in ->ndo_init() because we'd have no way to properly undo this operation in ->ndo_uninit(). Instead, let's register the session and the netdevice in two different steps and protect the session's device pointer with RCU. And now that we allow the session's .dev field to be NULL, we don't need to prevent the netdevice from being removed anymore. So we can drop the dev_hold() and dev_put() calls in l2tp_eth_create() and l2tp_eth_dev_uninit(). Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: - Update another 'goto out' in l2tp_eth_create() - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ee28de6bbd78c2e18111a0aef43ea746f28d2073 upstream.

Sessions must be initialised before being made externally visible by
l2tp_session_register(). Otherwise the session may be concurrently
deleted before being initialised, which can confuse the deletion path
and eventually lead to kernel oops.

Therefore, we need to move l2tp_session_register() down in
l2tp_eth_create(), but also handle the intermediate step where only the
session or the netdevice has been registered.

We can't just call l2tp_session_register() in ->ndo_init() because
we'd have no way to properly undo this operation in ->ndo_uninit().
Instead, let's register the session and the netdevice in two different
steps and protect the session's device pointer with RCU.

And now that we allow the session's .dev field to be NULL, we don't
need to prevent the netdevice from being removed anymore. So we can
drop the dev_hold() and dev_put() calls in l2tp_eth_create() and
l2tp_eth_dev_uninit().

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - Update another 'goto out' in l2tp_eth_create()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: don't register sessions in l2tp_session_create() 2018-02-13T18:32:11+00:00 Guillaume Nault g.nault@alphalink.fr 2017-10-27T14:51:50+00:00 b102bfc2a90d14f342580285782a9a51c74f7369 commit 3953ae7b218df4d1e544b98a393666f9ae58a78c upstream. Sessions created by l2tp_session_create() aren't fully initialised: some pseudo-wire specific operations need to be done before making the session usable. Therefore the PPP and Ethernet pseudo-wires continue working on the returned l2tp session while it's already been exposed to the rest of the system. This can lead to various issues. In particular, the session may enter the deletion process before having been fully initialised, which will confuse the session removal code. This patch moves session registration out of l2tp_session_create(), so that callers can control when the session is exposed to the rest of the system. This is done by the new l2tp_session_register() function. Only pppol2tp_session_create() can be easily converted to avoid modifying its session after registration (the debug message is dropped in order to avoid the need for holding a reference on the session). For pppol2tp_connect() and l2tp_eth_create()), more work is needed. That'll be done in followup patches. For now, let's just register the session right after its creation, like it was done before. The only difference is that we can easily take a reference on the session before registering it, so, at least, we're sure it's not going to be freed while we're working on it. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 3953ae7b218df4d1e544b98a393666f9ae58a78c upstream.

Sessions created by l2tp_session_create() aren't fully initialised:
some pseudo-wire specific operations need to be done before making the
session usable. Therefore the PPP and Ethernet pseudo-wires continue
working on the returned l2tp session while it's already been exposed to
the rest of the system.
This can lead to various issues. In particular, the session may enter
the deletion process before having been fully initialised, which will
confuse the session removal code.

This patch moves session registration out of l2tp_session_create(), so
that callers can control when the session is exposed to the rest of the
system. This is done by the new l2tp_session_register() function.

Only pppol2tp_session_create() can be easily converted to avoid
modifying its session after registration (the debug message is dropped
in order to avoid the need for holding a reference on the session).

For pppol2tp_connect() and l2tp_eth_create()), more work is needed.
That'll be done in followup patches. For now, let's just register the
session right after its creation, like it was done before. The only
difference is that we can easily take a reference on the session before
registering it, so, at least, we're sure it's not going to be freed
while we're working on it.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: ensure sessions are freed after their PPPOL2TP socket 2018-02-13T18:32:11+00:00 Guillaume Nault g.nault@alphalink.fr 2017-09-22T13:39:23+00:00 7823d6b02eb19708df5d1171006dcfc4e892530d commit cdd10c9627496ad25c87ce6394e29752253c69d3 upstream. If l2tp_tunnel_delete() or l2tp_tunnel_closeall() deletes a session right after pppol2tp_release() orphaned its socket, then the 'sock' variable of the pppol2tp_session_close() callback is NULL. Yet the session is still used by pppol2tp_release(). Therefore we need to take an extra reference in any case, to prevent l2tp_tunnel_delete() or l2tp_tunnel_closeall() from freeing the session. Since the pppol2tp_session_close() callback is only set if the session is associated to a PPPOL2TP socket and that both l2tp_tunnel_delete() and l2tp_tunnel_closeall() hold the PPPOL2TP socket before calling pppol2tp_session_close(), we're sure that pppol2tp_session_close() and pppol2tp_session_destruct() are paired and called in the right order. So the reference taken by the former will be released by the later. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit cdd10c9627496ad25c87ce6394e29752253c69d3 upstream.

If l2tp_tunnel_delete() or l2tp_tunnel_closeall() deletes a session
right after pppol2tp_release() orphaned its socket, then the 'sock'
variable of the pppol2tp_session_close() callback is NULL. Yet the
session is still used by pppol2tp_release().

Therefore we need to take an extra reference in any case, to prevent
l2tp_tunnel_delete() or l2tp_tunnel_closeall() from freeing the session.

Since the pppol2tp_session_close() callback is only set if the session
is associated to a PPPOL2TP socket and that both l2tp_tunnel_delete()
and l2tp_tunnel_closeall() hold the PPPOL2TP socket before calling
pppol2tp_session_close(), we're sure that pppol2tp_session_close() and
pppol2tp_session_destruct() are paired and called in the right order.
So the reference taken by the former will be released by the later.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: push all ppp pseudowire shutdown through .release handler 2018-02-13T18:32:11+00:00 Tom Parkin tparkin@katalix.com 2013-03-19T06:11:21+00:00 4c563277c65bf9849ecbeb451cef15bc510a1968 commit cf2f5c886a209377daefd5d2ba0bcd49c3887813 upstream. If userspace deletes a ppp pseudowire using the netlink API, either by directly deleting the session or by deleting the tunnel that contains the session, we need to tear down the corresponding pppox channel. Rather than trying to manage two pppox unbind codepaths, switch the netlink and l2tp_core session_close handlers to close via. the l2tp_ppp socket .release handler. Signed-off-by: Tom Parkin <tparkin@katalix.com> Signed-off-by: James Chapman <jchapman@katalix.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit cf2f5c886a209377daefd5d2ba0bcd49c3887813 upstream.

If userspace deletes a ppp pseudowire using the netlink API, either by
directly deleting the session or by deleting the tunnel that contains the
session, we need to tear down the corresponding pppox channel.

Rather than trying to manage two pppox unbind codepaths, switch the netlink
and l2tp_core session_close handlers to close via. the l2tp_ppp socket
.release handler.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: purge session reorder queue on delete 2018-02-13T18:32:11+00:00 Tom Parkin tparkin@katalix.com 2013-03-19T06:11:20+00:00 2dc59c2f29d0ee5ebbf0595a46aba52a6abbecdf commit 4c6e2fd35460208596fa099ee0750a4b0438aa5c upstream. Add calls to l2tp_session_queue_purge as a part of l2tp_tunnel_closeall and l2tp_session_delete. Pseudowire implementations which are deleted only via. l2tp_core l2tp_session_delete calls can dispense with their own code for flushing the reorder queue. Signed-off-by: Tom Parkin <tparkin@katalix.com> Signed-off-by: James Chapman <jchapman@katalix.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 4c6e2fd35460208596fa099ee0750a4b0438aa5c upstream.

Add calls to l2tp_session_queue_purge as a part of l2tp_tunnel_closeall
and l2tp_session_delete.  Pseudowire implementations which are deleted only
via. l2tp_core l2tp_session_delete calls can dispense with their own code for
flushing the reorder queue.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: add session reorder queue purge function to core 2018-02-13T18:32:10+00:00 Tom Parkin tparkin@katalix.com 2013-03-19T06:11:19+00:00 4fa2c620f1a39794da3df4a025b39b18480f64b2 commit 48f72f92b31431c40279b0fba6c5588e07e67d95 upstream. If an l2tp session is deleted, it is necessary to delete skbs in-flight on the session's reorder queue before taking it down. Rather than having each pseudowire implementation reaching into the l2tp_session struct to handle this itself, provide a function in l2tp_core to purge the session queue. Signed-off-by: Tom Parkin <tparkin@katalix.com> Signed-off-by: James Chapman <jchapman@katalix.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: use non-atomic increment on rx_errors] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 48f72f92b31431c40279b0fba6c5588e07e67d95 upstream.

If an l2tp session is deleted, it is necessary to delete skbs in-flight
on the session's reorder queue before taking it down.

Rather than having each pseudowire implementation reaching into the
l2tp_session struct to handle this itself, provide a function in l2tp_core to
purge the session queue.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: use non-atomic increment on rx_errors]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: don't use l2tp_tunnel_find() in l2tp_ip and l2tp_ip6 2018-01-01T20:51:02+00:00 Guillaume Nault g.nault@alphalink.fr 2017-11-03T15:49:00+00:00 9b4658f3daaf2070c871eac06fbee7cebeb18ce8 commit 8f7dc9ae4a7aece9fbc3e6637bdfa38b36bcdf09 upstream. Using l2tp_tunnel_find() in l2tp_ip_recv() is wrong for two reasons: * It doesn't take a reference on the returned tunnel, which makes the call racy wrt. concurrent tunnel deletion. * The lookup is only based on the tunnel identifier, so it can return a tunnel that doesn't match the packet's addresses or protocol. For example, a packet sent to an L2TPv3 over IPv6 tunnel can be delivered to an L2TPv2 over UDPv4 tunnel. This is worse than a simple cross-talk: when delivering the packet to an L2TP over UDP tunnel, the corresponding socket is UDP, where ->sk_backlog_rcv() is NULL. Calling sk_receive_skb() will then crash the kernel by trying to execute this callback. And l2tp_tunnel_find() isn't even needed here. __l2tp_ip_bind_lookup() properly checks the socket binding and connection settings. It was used as a fallback mechanism for finding tunnels that didn't have their data path registered yet. But it's not limited to this case and can be used to replace l2tp_tunnel_find() in the general case. Fix l2tp_ip6 in the same way. Fixes: 0d76751fad77 ("l2tp: Add L2TPv3 IP encapsulation (no UDP) support") Fixes: a32e0eec7042 ("l2tp: introduce L2TPv3 IP encapsulation support for IPv6") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: - Always look up in init_net - Drop changes in l2tp_ip6.c - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 8f7dc9ae4a7aece9fbc3e6637bdfa38b36bcdf09 upstream.

Using l2tp_tunnel_find() in l2tp_ip_recv() is wrong for two reasons:

  * It doesn't take a reference on the returned tunnel, which makes the
    call racy wrt. concurrent tunnel deletion.

  * The lookup is only based on the tunnel identifier, so it can return
    a tunnel that doesn't match the packet's addresses or protocol.

For example, a packet sent to an L2TPv3 over IPv6 tunnel can be
delivered to an L2TPv2 over UDPv4 tunnel. This is worse than a simple
cross-talk: when delivering the packet to an L2TP over UDP tunnel, the
corresponding socket is UDP, where ->sk_backlog_rcv() is NULL. Calling
sk_receive_skb() will then crash the kernel by trying to execute this
callback.

And l2tp_tunnel_find() isn't even needed here. __l2tp_ip_bind_lookup()
properly checks the socket binding and connection settings. It was used
as a fallback mechanism for finding tunnels that didn't have their data
path registered yet. But it's not limited to this case and can be used
to replace l2tp_tunnel_find() in the general case.

Fix l2tp_ip6 in the same way.

Fixes: 0d76751fad77 ("l2tp: Add L2TPv3 IP encapsulation (no UDP) support")
Fixes: a32e0eec7042 ("l2tp: introduce L2TPv3 IP encapsulation support for IPv6")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - Always look up in init_net
 - Drop changes in l2tp_ip6.c
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
l2tp: hold tunnel socket when handling control frames in l2tp_ip and l2tp_ip6 2018-01-01T20:51:01+00:00 Guillaume Nault g.nault@alphalink.fr 2017-03-29T06:44:59+00:00 9b9d4fd4f7e21c19718691fca547d5445639a96e commit 94d7ee0baa8b764cf64ad91ed69464c1a6a0066b upstream. The code following l2tp_tunnel_find() expects that a new reference is held on sk. Either sk_receive_skb() or the discard_put error path will drop a reference from the tunnel's socket. This issue exists in both l2tp_ip and l2tp_ip6. Fixes: a3c18422a4b4 ("l2tp: hold socket before dropping lock in l2tp_ip{, 6}_recv()") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: - Drop changes to l2tp_ip6.c - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 94d7ee0baa8b764cf64ad91ed69464c1a6a0066b upstream.

The code following l2tp_tunnel_find() expects that a new reference is
held on sk. Either sk_receive_skb() or the discard_put error path will
drop a reference from the tunnel's socket.

This issue exists in both l2tp_ip and l2tp_ip6.

Fixes: a3c18422a4b4 ("l2tp: hold socket before dropping lock in l2tp_ip{, 6}_recv()")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - Drop changes to l2tp_ip6.c
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>