This helper function allows family implementations to access
their family's attrbuf. This gets rid of the attrbuf usage
in families, and also adds locking validation, since it's not
valid to use the attrbuf with parallel_ops or outside of the
dumpit callback.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit bb9b18fb ("genl: Add genlmsg_new_unicast() for
unicast message allocation")'.

Nothing wrong with it; its no longer needed since this was only for
mmapped netlink support.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Operations with the GENL_ADMIN_PERM flag fail permissions checks because
this flag means we call netlink_capable, which uses the init user ns.

Instead, let's introduce a new flag, GENL_UNS_ADMIN_PERM for operations
which should be allowed inside a user namespace.

The motivation for this is to be able to run openvswitch in unprivileged
containers. I've tested this and it seems to work, but I really have no
idea about the security consequences of this patch, so thoughts would be
much appreciated.

v2: use the GENL_UNS_ADMIN_PERM flag instead of a check in each function
v3: use separate ifs for UNS_ADMIN_PERM and ADMIN_PERM, instead of one
    massive one
Reported-by: NJames Page <james.page@canonical.com>
Signed-off-by: NTycho Andersen <tycho.andersen@canonical.com>
CC: Eric Biederman <ebiederm@xmission.com>
CC: Pravin Shelar <pshelar@ovn.org>
CC: Justin Pettit <jpettit@nicira.com>
CC: "David S. Miller" <davem@davemloft.net>
Acked-by: NPravin B Shelar <pshelar@ovn.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bug fix for adding n_groups to the computation forgot
to adjust ">=" to ">" to keep the condition correct.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Multicast groups are stored in global buffer. Check for needed buffer size
incorrectly compares buffer size to first id for family. This means that
for families with more than one mcast id one may allocate too small buffer
and end up writing rest of the groups to some unallocated memory. Fix the
buffer size check to compare allocated space to last mcast id for the
family.

Tested on ARM using kernel 3.14
Signed-off-by: NMatti Vaittinen <matti.vaittinen@nokia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The start callback allows the caller to set up a context for the
dump callbacks. Presumably, the context can then be destroyed in
the done callback.
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch makes lockdep_genl_is_held return bool to improve
readability due to this particular function only using either
one or zero as its return value.

No functional change.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The genl_notify function has too many arguments for no real reason - all
callers use genl_info to get them anyway. Just pass the genl_info down to
genl_notify.
Signed-off-by: NJiri Benc <jbenc@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.

This makes the very common pattern of

  if (genlmsg_end(...) < 0) { ... }

be a whole bunch of dead code. Many places also simply do

  return nlmsg_end(...);

and the caller is expected to deal with it.

This also commonly (at least for me) causes errors, because it is very
common to write

  if (my_function(...))
    /* error condition */

and if my_function() does "return nlmsg_end()" this is of course wrong.

Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.

Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did

-	return nlmsg_end(...);
+	nlmsg_end(...);
+	return 0;

I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.

One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In addition to the problem Jeff Layton reported, I looked at the code
and reproduced the same warning by subscribing and removing the genl
family with a socket still open. This is a fairly tricky race which
originates in the fact that generic netlink allows the family to go
away while sockets are still open - unlike regular netlink which has
a module refcount for every open socket so in general this cannot be
triggered.

Trying to resolve this issue by the obvious locking isn't possible as
it will result in deadlocks between unregistration and group unbind
notification (which incidentally lockdep doesn't find due to the home
grown locking in the netlink table.)

To really resolve this, introduce a "closing socket" reference counter
(for generic netlink only, as it's the only affected family) in the
core netlink code and use that in generic netlink to wait for all the
sockets that are being closed at the same time as a generic netlink
family is removed.

This fixes the race that when a socket is closed, it will should call
the unbind, but if the family is removed at the same time the unbind
will not find it, leading to the warning. The real problem though is
that in this case the unbind could actually find a new family that is
registered to have a multicast group with the same ID, and call its
mcast_unbind() leading to confusing.

Also remove the warning since it would still trigger, but is now no
longer a problem.

This also moves the code in af_netlink.c to before unreferencing the
module to avoid having the same problem in the normal non-genl case.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jeff Layton reported that he could trigger the multicast unbind warning
in generic netlink using trinity. I originally thought it was a race
condition between unregistering the generic netlink family and closing
the socket, but there's a far simpler explanation: genetlink currently
allows subscribing to groups that don't (yet) exist, and the warning is
triggered when unsubscribing again while the group still doesn't exist.

Originally, I had a warning in the subscribe case and accepted it out of
userspace API concerns, but the warning was of course wrong and removed
later.

However, I now think that allowing userspace to subscribe to groups that
don't exist is wrong and could possibly become a security problem:
Consider a (new) genetlink family implementing a permission check in
the mcast_bind() function similar to the like the audit code does today;
it would be possible to bypass the permission check by guessing the ID
and subscribing to the group it exists. This is only possible in case a
family like that would be dynamically loaded, but it doesn't seem like a
huge stretch, for example wireless may be loaded when you plug in a USB
device.

To avoid this reject such subscription attempts.

If this ends up causing userspace issues we may need to add a workaround
in af_netlink to deny such requests but not return an error.
Reported-by: NJeff Layton <jeff.layton@primarydata.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Users can request to bind to arbitrary multicast groups, so warning
when the requested group number is out of range is not appropriate.

And with the warning removed, and the 'err' variable properly given
an initial value, we can remove 'found' altogether.
Reported-by: NSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Netlink families can exist in multiple namespaces, and for the most
part multicast subscriptions are per network namespace. Thus it only
makes sense to have bind/unbind notifications per network namespace.

To achieve this, pass the network namespace of a given client socket
to the bind/unbind functions.

Also do this in generic netlink, and there also make sure that any
bind for multicast groups that only exist in init_net is rejected.
This isn't really a problem if it is accepted since a client in a
different namespace will never receive any notifications from such
a group, but it can confuse the family if not rejected (it's also
possible to silently (without telling the family) accept it, but it
would also have to be ignored on unbind so families that take any
kind of action on bind/unbind won't do unnecessary work for invalid
clients like that.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In order to make the newly fixed multicast bind/unbind
functionality in generic netlink, pass them down to the
appropriate family.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

the local variable ops and n_ops were just read out from family,
and not changed, hence no need to assign back.

Validation functions should operate on const parameters and not
change anything.
Signed-off-by: NCheng Renquan <crquan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is possible by passing a netlink socket to a more privileged
executable and then to fool that executable into writing to the socket
data that happens to be valid netlink message to do something that
privileged executable did not intend to do.

To keep this from happening replace bare capable and ns_capable calls
with netlink_capable, netlink_net_calls and netlink_ns_capable calls.
Which act the same as the previous calls except they verify that the
opener of the socket had the desired permissions as well.
Reported-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allocates a new sk_buff large enough to cover the specified payload
plus required Netlink headers. Will check receiving socket for
memory mapped i/o capability and use it if enabled. Will fall back
to non-mapped skb if message size exceeds the frame size of the ring.
Signed-of-by: NThomas Graf <tgraf@suug.ch>
Reviewed-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NJesse Gross <jesse@nicira.com>

The pmcraid driver is abusing the genetlink API and is using its
family ID as the multicast group ID, which is invalid and may
belong to somebody else (and likely will.)

Make it use the correct API, but since this may already be used
as-is by userspace, reserve a family ID for this code and also
reserve that group ID to not break userspace assumptions.

My previous patch broke event delivery in the driver as I missed
that it wasn't using the right API and forgot to update it later
in my series.

While changing this, I noticed that the genetlink code could use
the static group ID instead of a strcmp(), so also do that for
the VFS_DQUOT family.

Cc: Anil Ravindranath <anil_ravindranath@pmc-sierra.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netlink/genetlink.c: In function ‘genl_validate_assign_mc_groups’:
net/netlink/genetlink.c:217: warning: ‘err’ may be used uninitialized in this
function

Commit 2a94fe48 ("genetlink: make multicast
groups const, prevent abuse") split genl_register_mc_group() in multiple
functions, but dropped the initialization of err.

Initialize err to zero to fix this.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Unfortunately, I introduced a tremendously stupid bug into
genlmsg_multicast() when doing all those multicast group
changes: it adjusts the group number, but then passes it
to genlmsg_multicast_netns() which does that again.

Somehow, my tests failed to catch this, so add a warning
into genlmsg_multicast_netns() and remove the offending
group ID adjustment.

Also add a warning to the similar code in other functions
so people who misuse them are more loudly warned.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Register generic netlink multicast groups as an array with
the family and give them contiguous group IDs. Then instead
of passing the global group ID to the various functions that
send messages, pass the ID relative to the family - for most
families that's just 0 because the only have one group.

This avoids the list_head and ID in each group, adding a new
field for the mcast group ID offset to the family.

At the same time, this allows us to prevent abusing groups
again like the quota and dropmon code did, since we can now
check that a family only uses a group it owns.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This doesn't really change anything, but prepares for the
next patch that will change the APIs to pass the group ID
within the family, rather than the global group ID.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's no reason to have the family pointer there since it
can just be passed internally where needed, so remove it.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There are no users of this API remaining, and we'll soon
change group registration to be static (like ops are now)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The quota code is abusing the genetlink API and is using
its family ID as the multicast group ID, which is invalid
and may belong to somebody else (and likely will.)

Make the quota code use the correct API, but since this
is already used as-is by userspace, reserve a family ID
for this code and also reserve that group ID to not break
userspace assumptions.
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The drop monitor code is abusing the genetlink API and is
statically using the generic netlink multicast group 1, even
if that group belongs to somebody else (which it invariably
will, since it's not reserved.)

Make the drop monitor code use the proper APIs to reserve a
group ID, but also reserve the group id 1 in generic netlink
code to preserve the userspace API. Since drop monitor can
be a module, don't clear the bit for it on unregistration.
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As suggested by David Miller, make genl_register_family_with_ops()
a macro and pass only the array, evaluating ARRAY_SIZE() in the
macro, this is a little safer.

The openvswitch has some indirection, assing ops/n_ops directly in
that code. This might ultimately just assign the pointers in the
family initializations, saving the struct genl_family_and_ops and
code (once mcast groups are handled differently.)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Sparse pointed out that the new flags variable I had added
shadowed an existing one, rename the new one to avoid that,
making the code clearer.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that the ops assignment is just two variables rather than a
long list iteration etc., there's no reason to separately export
__genl_register_family() and __genl_register_family_with_ops().

Unify the two functions into __genl_register_family() and make
genl_register_family_with_ops() call it after assigning the ops.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow making the ops array const by not modifying the ops
flags on registration but rather only when ops are sent
out in the family information.

No users are updated yet except for the pre_doit/post_doit
calls in wireless (the only ones that exist now.)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of using a linked list, use an array. This reduces
the data size needed by the users of genetlink, for example
in wireless (net/wireless/nl80211.c) on 64-bit it frees up
over 1K of data space.

Remove the attempted sending of CTRL_CMD_NEWOPS ctrl event
since genl_ctrl_event(CTRL_CMD_NEWOPS, ...) only returns
-EINVAL anyway, therefore no such event could ever be sent.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

genl_register_ops() is still needed for internal registration,
but is no longer available to users of the API.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

netlink dump operations take module as parameter to hold
reference for entire netlink dump duration.
Currently it holds ref only on genl module which is not correct
when we use ops registered to genl from another module.
Following patch adds module pointer to genl_ops so that netlink
can hold ref count on it.

CC: Jesse Gross <jesse@nicira.com>
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In case of genl-family with parallel ops off, dumpif() callback
is expected to run under genl_lock, But commit def31174
(genl: Allow concurrent genl callbacks.) changed this behaviour
where only first dumpit() op was called under genl-lock.
For subsequent dump, only nlk->cb_lock was taken.
Following patch fixes it by defining locked dumpit() and done()
callback which takes care of genl-locking.

CC: Jesse Gross <jesse@nicira.com>
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 58ad436f.

It turns out that the change introduced a potential deadlock
by causing a locking dependency with netlink's cb_mutex. I
can't seem to find a way to resolve this without doing major
changes to the locking, so revert this.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Acked-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When dumping generic netlink families, only the first dump call
is locked with genl_lock(), which protects the list of families,
and thus subsequent calls can access the data without locking,
racing against family addition/removal. This can cause a crash.
Fix it - the locking needs to be conditional because the first
time around it's already locked.

A similar bug was reported to me on an old kernel (3.4.47) but
the exact scenario that happened there is no longer possible,
on those kernels the first round wasn't locked either. Looking
at the current code I found the race described above, which had
also existed on the old kernel.

Cc: stable@vger.kernel.org
Reported-by: NAndrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, it is not possible to use neither NLM_F_EXCL nor
NLM_F_REPLACE from genetlink. This is due to this checking in
genl_family_rcv_msg:

	if (nlh->nlmsg_flags & NLM_F_DUMP)

NLM_F_DUMP is NLM_F_MATCH|NLM_F_ROOT. Thus, if NLM_F_EXCL or
NLM_F_REPLACE flag is set, genetlink believes that you're
requesting a dump and it calls the .dumpit callback.

The solution that I propose is to refine this checking to
make it stricter:

	if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP)

And given the combination NLM_F_REPLACE and NLM_F_EXCL does
not make sense to me, it removes the ambiguity.

There was a patch that tried to fix this some time ago (0ab03c2b
netlink: test for all flags of the NLM_F_DUMP composite) but it
tried to resolve this ambiguity in *all* existing netlink subsystems,
not only genetlink. That patch was reverted since it broke iproute2,
which is using NLM_F_ROOT to request the dump of the routing cache.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Requesting external module with cb_lock taken can result in
the deadlock like showed below:

[ 2458.111347] Showing all locks held in the system:
[ 2458.111347] 1 lock held by NetworkManager/582:
[ 2458.111347]  #0:  (cb_lock){++++++}, at: [<ffffffff8162bc79>] genl_rcv+0x19/0x40
[ 2458.111347] 1 lock held by modprobe/603:
[ 2458.111347]  #0:  (cb_lock){++++++}, at: [<ffffffff8162baa5>] genl_lock_all+0x15/0x30

[ 2461.579457] SysRq : Show Blocked State
[ 2461.580103]   task                        PC stack   pid father
[ 2461.580103] NetworkManager  D ffff880034b84500  4040   582      1 0x00000080
[ 2461.580103]  ffff8800197ff720 0000000000000046 00000000001d5340 ffff8800197fffd8
[ 2461.580103]  ffff8800197fffd8 00000000001d5340 ffff880019631700 7fffffffffffffff
[ 2461.580103]  ffff8800197ff880 ffff8800197ff878 ffff880019631700 ffff880019631700
[ 2461.580103] Call Trace:
[ 2461.580103]  [<ffffffff817355f9>] schedule+0x29/0x70
[ 2461.580103]  [<ffffffff81731ad1>] schedule_timeout+0x1c1/0x360
[ 2461.580103]  [<ffffffff810e69eb>] ? mark_held_locks+0xbb/0x140
[ 2461.580103]  [<ffffffff817377ac>] ? _raw_spin_unlock_irq+0x2c/0x50
[ 2461.580103]  [<ffffffff810e6b6d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
[ 2461.580103]  [<ffffffff81736398>] wait_for_completion_killable+0xe8/0x170
[ 2461.580103]  [<ffffffff810b7fa0>] ? wake_up_state+0x20/0x20
[ 2461.580103]  [<ffffffff81095825>] call_usermodehelper_exec+0x1a5/0x210
[ 2461.580103]  [<ffffffff817362ed>] ? wait_for_completion_killable+0x3d/0x170
[ 2461.580103]  [<ffffffff81095cc3>] __request_module+0x1b3/0x370
[ 2461.580103]  [<ffffffff810e6b6d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
[ 2461.580103]  [<ffffffff8162c5c9>] ctrl_getfamily+0x159/0x190
[ 2461.580103]  [<ffffffff8162d8a4>] genl_family_rcv_msg+0x1f4/0x2e0
[ 2461.580103]  [<ffffffff8162d990>] ? genl_family_rcv_msg+0x2e0/0x2e0
[ 2461.580103]  [<ffffffff8162da1e>] genl_rcv_msg+0x8e/0xd0
[ 2461.580103]  [<ffffffff8162b729>] netlink_rcv_skb+0xa9/0xc0
[ 2461.580103]  [<ffffffff8162bc88>] genl_rcv+0x28/0x40
[ 2461.580103]  [<ffffffff8162ad6d>] netlink_unicast+0xdd/0x190
[ 2461.580103]  [<ffffffff8162b149>] netlink_sendmsg+0x329/0x750
[ 2461.580103]  [<ffffffff815db849>] sock_sendmsg+0x99/0xd0
[ 2461.580103]  [<ffffffff810bb58f>] ? local_clock+0x5f/0x70
[ 2461.580103]  [<ffffffff810e96e8>] ? lock_release_non_nested+0x308/0x350
[ 2461.580103]  [<ffffffff815dbc6e>] ___sys_sendmsg+0x39e/0x3b0
[ 2461.580103]  [<ffffffff810565af>] ? kvm_clock_read+0x2f/0x50
[ 2461.580103]  [<ffffffff810218b9>] ? sched_clock+0x9/0x10
[ 2461.580103]  [<ffffffff810bb2bd>] ? sched_clock_local+0x1d/0x80
[ 2461.580103]  [<ffffffff810bb448>] ? sched_clock_cpu+0xa8/0x100
[ 2461.580103]  [<ffffffff810e33ad>] ? trace_hardirqs_off+0xd/0x10
[ 2461.580103]  [<ffffffff810bb58f>] ? local_clock+0x5f/0x70
[ 2461.580103]  [<ffffffff810e3f7f>] ? lock_release_holdtime.part.28+0xf/0x1a0
[ 2461.580103]  [<ffffffff8120fec9>] ? fget_light+0xf9/0x510
[ 2461.580103]  [<ffffffff8120fe0c>] ? fget_light+0x3c/0x510
[ 2461.580103]  [<ffffffff815dd1d2>] __sys_sendmsg+0x42/0x80
[ 2461.580103]  [<ffffffff815dd222>] SyS_sendmsg+0x12/0x20
[ 2461.580103]  [<ffffffff81741ad9>] system_call_fastpath+0x16/0x1b
[ 2461.580103] modprobe        D ffff88000f2c8000  4632   603    602 0x00000080
[ 2461.580103]  ffff88000f04fba8 0000000000000046 00000000001d5340 ffff88000f04ffd8
[ 2461.580103]  ffff88000f04ffd8 00000000001d5340 ffff8800377d4500 ffff8800377d4500
[ 2461.580103]  ffffffff81d0b260 ffffffff81d0b268 ffffffff00000000 ffffffff81d0b2b0
[ 2461.580103] Call Trace:
[ 2461.580103]  [<ffffffff817355f9>] schedule+0x29/0x70
[ 2461.580103]  [<ffffffff81736d4d>] rwsem_down_write_failed+0xed/0x1a0
[ 2461.580103]  [<ffffffff810bb200>] ? update_cpu_load_active+0x10/0xb0
[ 2461.580103]  [<ffffffff8137b473>] call_rwsem_down_write_failed+0x13/0x20
[ 2461.580103]  [<ffffffff8173492d>] ? down_write+0x9d/0xb2
[ 2461.580103]  [<ffffffff8162baa5>] ? genl_lock_all+0x15/0x30
[ 2461.580103]  [<ffffffff8162baa5>] genl_lock_all+0x15/0x30
[ 2461.580103]  [<ffffffff8162cbb3>] genl_register_family+0x53/0x1f0
[ 2461.580103]  [<ffffffffa01dc000>] ? 0xffffffffa01dbfff
[ 2461.580103]  [<ffffffff8162d650>] genl_register_family_with_ops+0x20/0x80
[ 2461.580103]  [<ffffffffa01dc000>] ? 0xffffffffa01dbfff
[ 2461.580103]  [<ffffffffa017fe84>] nl80211_init+0x24/0xf0 [cfg80211]
[ 2461.580103]  [<ffffffffa01dc000>] ? 0xffffffffa01dbfff
[ 2461.580103]  [<ffffffffa01dc043>] cfg80211_init+0x43/0xdb [cfg80211]
[ 2461.580103]  [<ffffffff810020fa>] do_one_initcall+0xfa/0x1b0
[ 2461.580103]  [<ffffffff8105cb93>] ? set_memory_nx+0x43/0x50
[ 2461.580103]  [<ffffffff810f75af>] load_module+0x1c6f/0x27f0
[ 2461.580103]  [<ffffffff810f2c90>] ? store_uevent+0x40/0x40
[ 2461.580103]  [<ffffffff810f82c6>] SyS_finit_module+0x86/0xb0
[ 2461.580103]  [<ffffffff81741ad9>] system_call_fastpath+0x16/0x1b
[ 2461.580103] Sched Debug Version: v0.10, 3.11.0-0.rc1.git4.1.fc20.x86_64 #1

Problem start to happen after adding net-pf-16-proto-16-family-nl80211
alias name to cfg80211 module by below commit (though that commit
itself is perfectly fine):

commit fb4e1568
Author: Marcel Holtmann <marcel@holtmann.org>
Date:   Sun Apr 28 16:22:06 2013 -0700

    nl80211: Add generic netlink module alias for cfg80211/nl80211
Reported-and-tested-by: NJeff Layton <jlayton@redhat.com>
Reported-by: NRichard W.M. Jones <rjones@redhat.com>
Signed-off-by: NStanislaw Gruszka <sgruszka@redhat.com>
Reviewed-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

'attrbuf' is malloced in genl_family_rcv_msg() when family->maxattr &&
family->parallel_ops, thus should be freed before leaving from the error
handling cases, otherwise it will cause memory leak.

Introduced by commit def31174
(genl: Allow concurrent genl callbacks.)
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>