we need to check proper socket type within ipv4_conntrack_defrag
function before referencing the nodefrag flag.

For example the tun driver receive path produces skbs with
AF_UNSPEC socket type, and so current code is causing unwanted
fragmented packets going out.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix checksum calculation in nf_nat_snmp_basic.

Based on patches by Clark Wang <wtweeker@163.com> and
Stephen Hemminger <shemminger@vyatta.com>.

https://bugzilla.kernel.org/show_bug.cgi?id=17622Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As soon as rcu_read_unlock() is called, there is no guarantee current
thread can safely derefence t pointer, rcu protected.

Fix is to copy t->alloc_size in a temporary variable.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ip_route_me_harder can't create the route cache when the outdev is the same
with the indev for the skbs whichout a valid protocol set.

__mkroute_input functions has this check:
1998         if (skb->protocol != htons(ETH_P_IP)) {
1999                 /* Not IP (i.e. ARP). Do not create route, if it is
2000                  * invalid for proxy arp. DNAT routes are always valid.
2001                  *
2002                  * Proxy arp feature have been extended to allow, ARP
2003                  * replies back to the same interface, to support
2004                  * Private VLAN switch technologies. See arp.c.
2005                  */
2006                 if (out_dev == in_dev &&
2007                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
2008                         err = -EINVAL;
2009                         goto cleanup;
2010                 }
2011         }

This patch gives the new skb a valid protocol to bypass this check. In order
to make ipt_REJECT work with bridges, you also need to enable ip_forward.

This patch also fixes a regression. When we used skb_copy_expand(), we
didn't have this issue stated above, as the protocol was properly set.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I initially noticed this because of the compiler warning below, but it
does seem to be a valid concern in the case where ct_sip_get_header()
returns 0 in the first iteration of the while loop.

net/netfilter/nf_conntrack_sip.c: In function 'sip_help_tcp':
net/netfilter/nf_conntrack_sip.c:1379: warning: 'ret' may be used uninitialized in this function
Signed-off-by: NSimon Horman <horms@verge.net.au>
[Patrick: changed NF_DROP to NF_ACCEPT]
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

transparent field of a socket is either inet_twsk(sk)->tw_transparent
for timewait sockets, or inet_sk(sk)->transparent for other sockets
(TCP/UDP).
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Special care should be taken when slow path is hit in ip_fragment() :

When walking through frags, we transfert truesize ownership from skb to
frags. Then if we hit a slow_path condition, we must undo this or risk
uncharging frags->truesize twice, and in the end, having negative socket
sk_wmem_alloc counter, or even freeing socket sooner than expected.

Many thanks to Nick Bowler, who provided a very clean bug report and
test program.

Thanks to Jarek for reviewing my first patch and providing a V2

While Nick bisection pointed to commit 2b85a34e (net: No more
expensive sock_hold()/sock_put() on each tx), underlying bug is older
(2.6.12-rc5)

A side effect is to extend work done in commit b2722b1c
(ip_fragment: also adjust skb->truesize for packets not owned by a
socket) to ipv6 as well.
Reported-and-bisected-by: NNick Bowler <nbowler@elliptictech.com>
Tested-by: NNick Bowler <nbowler@elliptictech.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Jarek Poplawski <jarkao2@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

skb->truesize is set in core network.

Dont change it unless dealing with fragments.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

skb->truesize is set in core network.

Dont change it unless dealing with fragments.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If a RST comes in immediately after checking sk->sk_err, tcp_poll will
return POLLIN but not POLLOUT.  Fix this by checking sk->sk_err at the end
of tcp_poll.  Additionally, ensure the correct order of operations on SMP
machines with memory barriers.
Signed-off-by: NTom Marshall <tdm.code@gmail.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Just use explicit casts, since we really can't change the
types of structures exported to userspace which have been
around for 15 years or so.
Reported-by: NDan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The family parameter xfrm_state_find is used to find a state matching a
certain policy. This value is set to the template's family
(encap_family) right before xfrm_state_find is called.
The family parameter is however also used to construct a temporary state
in xfrm_state_find itself which is wrong for inter-family scenarios
because it produces a selector for the wrong family. Since this selector
is included in the xfrm_user_acquire structure, user space programs
misinterpret IPv6 addresses as IPv4 and vice versa.
This patch splits up the original init_tempsel function into a part that
initializes the selector respectively the props and id of the temporary
state, to allow for differing ip address families whithin the state.
Signed-off-by: NThomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a driver doesn't fill the entire buffer, old
heap contents may remain, and if it also doesn't
update the length properly, this old heap content
will be copied back to userspace.

It is very unlikely that this happens in any of
the drivers using private ioctls since it would
show up as junk being reported by iwpriv, but it
seems better to be safe here, so use kzalloc.
Reported-by: NJeff Mahoney <jeffm@suse.com>
Cc: stable@kernel.org
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

ipv6 can be a module, we should test CONFIG_IPV6 and CONFIG_IPV6_MODULE
to enable ipv6 bits in ip_gre.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qlcnic driver allocates rx skbs and gives to hardware too bytes of extra
storage, allowing for corruption of kernel data.

NET_IP_ALIGN being 0 on some platforms (including x86), drivers should
not assume it's 2.

rds_ring->skb_size = rds_ring->dma_size + NET_IP_ALIGN;
...
skb = dev_alloc_skb(rds_ring->skb_size);
skb_reserve(skb, 2);
pci_map_single(pdev, skb->data, rds_ring->dma_size, PCI_DMA_FROMDEVICE);

(and rds_ring->skb_size == rds_ring->dma_size) -> bug


Because of extra alignment (1500 + 32) -> four extra bytes are available
before the struct skb_shared_info, so corruption is not noticed.

Note: this driver could use netdev_alloc_skb_ip_align()
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Direct Cache Access is not supported on IOAT ver.3.0 multiple-IOH platforms.
This patch blocks registering of dca providers when multiple IOH detected with IOAT ver.3.0.
Signed-off-by: NMaciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We cannot use rcu_dereference_bh safely in netpoll_rx as we may
be called with IRQs disabled.  We could however simply disable
IRQs as that too causes BH to be disabled and is safe in either
case.

Thanks to John Linville for discovering this bug and providing
a patch.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

sctp_packet_config() is called when getting the packet ready
for appending of chunks.  The function should not touch the
current state, since it's possible to ping-pong between two
transports when sending, and that can result packet corruption
followed by skb overlfow crash.
Reported-by: NThomas Dreibholz <dreibh@iem.uni-due.de>
Signed-off-by: NVlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When uCode error condition detected, driver try to perform either
rf reset or firmware reload in order bring device back to
working condition.

If rf reset is required and scan is in process, there is no need
to issue rf reset since scan already reset the rf.

If firmware reload is required and scan is in process, skip the
reload request. There is a possibility firmware reload during
scan cause problem.

[  485.804046] WARNING: at net/mac80211/main.c:310 ieee80211_restart_hw+0x28/0x62()
[  485.804049] Hardware name: Latitude E6400
[  485.804052] ieee80211_restart_hw called with hardware scan in progress
[  485.804054] Modules linked in: iwlagn iwlcore bnep sco rfcomm l2cap crc16 bluetooth [last unloaded: iwlcore]
[  485.804069] Pid: 812, comm: kworker/u:3 Tainted: G        W   2.6.36-rc3-wl+ #74
[  485.804072] Call Trace:
[  485.804079]  [<c103019a>] warn_slowpath_common+0x60/0x75
[  485.804084]  [<c1030213>] warn_slowpath_fmt+0x26/0x2a
[  485.804089]  [<c145da67>] ieee80211_restart_hw+0x28/0x62
[  485.804102]  [<f8b35dc6>] iwl_bg_restart+0x113/0x150 [iwlagn]
[  485.804108]  [<c10415d5>] process_one_work+0x181/0x25c
[  485.804119]  [<f8b35cb3>] ? iwl_bg_restart+0x0/0x150 [iwlagn]
[  485.804124]  [<c104190a>] worker_thread+0xf9/0x1f2
[  485.804128]  [<c1041811>] ? worker_thread+0x0/0x1f2
[  485.804133]  [<c10451b0>] kthread+0x64/0x69
[  485.804137]  [<c104514c>] ? kthread+0x0/0x69
[  485.804141]  [<c1002df6>] kernel_thread_helper+0x6/0x10
[  485.804145] ---[ end trace 3d4ebdc02d524bbb ]---
[  485.804148] WG> 1
[  485.804153] Pid: 812, comm: kworker/u:3 Tainted: G        W   2.6.36-rc3-wl+ #74
[  485.804156] Call Trace:
[  485.804161]  [<c145da9b>] ? ieee80211_restart_hw+0x5c/0x62
[  485.804172]  [<f8b35dcb>] iwl_bg_restart+0x118/0x150 [iwlagn]
[  485.804177]  [<c10415d5>] process_one_work+0x181/0x25c
[  485.804188]  [<f8b35cb3>] ? iwl_bg_restart+0x0/0x150 [iwlagn]
[  485.804192]  [<c104190a>] worker_thread+0xf9/0x1f2
[  485.804197]  [<c1041811>] ? worker_thread+0x0/0x1f2
[  485.804201]  [<c10451b0>] kthread+0x64/0x69
[  485.804205]  [<c104514c>] ? kthread+0x0/0x69
[  485.804209]  [<c1002df6>] kernel_thread_helper+0x6/0x10
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>

If the alloc_skb() fails then we return 65431 instead of -ENOBUFS
(-105).
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The atlx drivers are sufficiently mature that we no longer need a separate
mailing list for them.  Move the discussion to netdev, so we can decommission
atl1-devel, which is now mostly spam.
Signed-off-by: NChris Snook <chris.snook@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixed formatting (tabs and line breaks).

The CHELSIO_GET_QSET_NUM device ioctl allows unprivileged users to read
4 bytes of uninitialized stack memory, because the "addr" member of the
ch_reg struct declared on the stack in cxgb_extension_ioctl() is not
altered or zeroed before being copied back to the user.  This patch
takes care of it.
Signed-off-by: NDan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixed formatting (tabs and line breaks).

The EQL_GETMASTRCFG device ioctl allows unprivileged users to read 16
bytes of uninitialized stack memory, because the "master_name" member of
the master_config_t struct declared on the stack in eql_g_master_cfg()
is not altered or zeroed before being copied back to the user.  This
patch takes care of it.
Signed-off-by: NDan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixed formatting (tabs and line breaks).

The TIOCGICOUNT device ioctl allows unprivileged users to read
uninitialized stack memory, because the "reserved" member of the
serial_icounter_struct struct declared on the stack in hso_get_count()
is not altered or zeroed before being copied back to the user.  This
patch takes care of it.
Signed-off-by: NDan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ip_local_out() is called with rcu_read_lock() held from ip_queue_xmit()
but not from other call sites.
Reported-and-bisected-by: NNick Bowler <nbowler@elliptictech.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The Thinkpad X100e seems to have some odd behaviour when the display is
powered off - the onboard r8169 starts generating rxfifo overflow errors.
The root cause of this has not yet been identified and may well be a
hardware design bug on the platform, but r8169 should be more resiliant to
this. This patch enables the rxfifo interrupt on 8168 devices and removes
the MAC version check in the interrupt handler, and the machine no longer
crashes when under network load while the screen turns off.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Acked-by: NFrancois Romieu <romieu@fr.zoreil.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There is no need to use spinlocks in vortex_{set|get}_wol.
This also fixes a bug:
[  254.214993] 3c59x 0000:00:0d.0: PME# enabled
[  254.215021] BUG: sleeping function called from invalid context at kernel/mutex.c:94
[  254.215030] in_atomic(): 0, irqs_disabled(): 1, pid: 4875, name: ethtool
[  254.215042] Pid: 4875, comm: ethtool Tainted: G        W   2.6.36-rc3+ #7
[  254.215049] Call Trace:
[  254.215050]  [] __might_sleep+0xb1/0xb6
[  254.215050]  [] mutex_lock+0x17/0x30
[  254.215050]  [] acpi_enable_wakeup_device_power+0x2b/0xb1
[  254.215050]  [] acpi_pm_device_sleep_wake+0x42/0x7f
[  254.215050]  [] acpi_pci_sleep_wake+0x5d/0x63
[  254.215050]  [] platform_pci_sleep_wake+0x1d/0x20
[  254.215050]  [] __pci_enable_wake+0x90/0xd0
[  254.215050]  [] acpi_set_WOL+0x8e/0xf5 [3c59x]
[  254.215050]  [] vortex_set_wol+0x4e/0x5e [3c59x]
[  254.215050]  [] dev_ethtool+0x1cf/0xb61
[  254.215050]  [] ? debug_mutex_free_waiter+0x45/0x4a
[  254.215050]  [] ? __mutex_lock_common+0x204/0x20e
[  254.215050]  [] ? __mutex_lock_slowpath+0x12/0x15
[  254.215050]  [] ? mutex_lock+0x23/0x30
[  254.215050]  [] dev_ioctl+0x42c/0x533
[  254.215050]  [] ? _cond_resched+0x8/0x1c
[  254.215050]  [] ? lock_page+0x1c/0x30
[  254.215050]  [] ? page_address+0x15/0x7c
[  254.215050]  [] ? filemap_fault+0x187/0x2c4
[  254.215050]  [] sock_ioctl+0x1d4/0x1e0
[  254.215050]  [] ? sock_ioctl+0x0/0x1e0
[  254.215050]  [] vfs_ioctl+0x19/0x33
[  254.215050]  [] do_vfs_ioctl+0x424/0x46f
[  254.215050]  [] ? selinux_file_ioctl+0x3c/0x40
[  254.215050]  [] sys_ioctl+0x40/0x5a
[  254.215050]  [] sysenter_do_call+0x12/0x22

vortex_set_wol protected with a spinlock, but nested  acpi_set_WOL acquires a mutex inside atomic context.
Ethtool operations are already serialized by RTNL mutex, so it is safe to drop the locks.
Signed-off-by: NDenis Kirjanov <dkirjanov@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If peer uses tiny MSS (say, 75 bytes) and similarly tiny advertised
window, the SWS logic will packetize to half the MSS unnecessarily.

This causes problems with some embedded devices.

However for large MSS devices we do want to half-MSS packetize
otherwise we never get enough packets into the pipe for things
like fast retransmit and recovery to work.

Be careful also to handle the case where MSS > window, otherwise
we'll never send until the probe timer.
Reported-by: Nツ Leandro Melo de Sales <leandroal@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

You cannot invoke __smp_call_function_single() unless the
architecture sets this symbol.
Reported-by: NDaniel Hellstrom <daniel@gaisler.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

On resume, before starting the PAL state machine, check if the
adjust_link() method is well supplied. If not, this would lead to a
NULL pointer dereference in the phy_state_machine() function.

This scenario can happen if the Ethernet driver call manually the PHY
functions instead of using the PAL state machine. The mv643xx_eth driver
is a such example.
Signed-off-by: NSimon Guinot <sguinot@lacie.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

netdev_wait_allrefs() waits that all references to a device vanishes.

It currently uses a _very_ pessimistic 250 ms delay between each probe.
Some users reported that no more than 4 devices can be dismantled per
second, this is a pretty serious problem for some setups.

Most of the time, a refcount is about to be released by an RCU callback,
that is still in flight because rollback_registered_many() uses a
synchronize_rcu() call instead of rcu_barrier(). Problem is visible if
number of online cpus is one, because synchronize_rcu() is then a no op.

time to remove 50 ipip tunnels on a UP machine :

before patch : real 11.910s
after patch : real 1.250s
Reported-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Reported-by: NOctavian Purdila <opurdila@ixiacom.com>
Reported-by: NBenjamin LaHaise <bcrl@kvack.org>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It was recently brought to my attention that 802.3ad mode bonds would no
longer form when using some network hardware after a driver update.
After snooping around I realized that the particular hardware was using
page-based skbs and found that skb->data did not contain a valid LACPDU
as it was not stored there.  That explained the inability to form an
802.3ad-based bond.  For balance-alb mode bonds this was also an issue
as ARPs would not be properly processed.

This patch fixes the issue in my tests and should be applied to 2.6.36
and as far back as anyone cares to add it to stable.

Thanks to Alexander Duyck <alexander.h.duyck@intel.com> and Jesse
Brandeburg <jesse.brandeburg@intel.com> for the suggestions on this one.
Signed-off-by: NAndy Gospodarek <andy@greyhouse.net>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Jesse Brandeburg <jesse.brandeburg@intel.com>
CC: stable@kerne.org
Signed-off-by: NJay Vosburgh <fubar@us.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In mergeable buffer case, we use headcount, log_num
and seg as indexes in same-size arrays, and
we know that headcount <= seg and
log_num equals either 0 or seg.

Therefore, the right thing to do is range-check seg,
not headcount as we do now: these will be different
if guest chains s/g descriptors (this does not
happen now, but we can not trust the guest).

Long term, we should add BUG_ON checks to verify
two other indexes are what we think they should be.
Reported-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

While integrating your man-pages patch for IP_NODEFRAG, I noticed
that this option is settable by setsockopt(), but not gettable by
getsockopt(). I suppose this is not intended. The (untested,
trivial) patch below adds getsockopt() support.
Signed-off-by: NMichael kerrisk <mtk.manpages@gmail.com>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After all these years, it turns out that the
    /proc/sys/net/ipv4/conf/*/force_igmp_version
parameter isn't fully implemented.

*Symptom*:
When set force_igmp_version to a value of 2, the kernel should only perform
multicast IGMPv2 operations (IETF rfc2236).  An host-initiated Join message
will be sent as a IGMPv2 Join message.  But if a IGMPv3 query message is
received, the host responds with a IGMPv3 join message.  Per rfc3376 and
rfc2236, a IGMPv2 host should treat a IGMPv3 query as a IGMPv2 query and
respond with an IGMPv2 Join message.

*Consequences*:
This is an issue when a IGMPv3 capable switch is the querier and will only
issue IGMPv3 queries (which double as IGMPv2 querys) and there's an
intermediate switch that is only IGMPv2 capable.  The intermediate switch
processes the initial v2 Join, but fails to recognize the IGMPv3 Join responses
to the Query, resulting in a dropped connection when the intermediate v2-only
switch times it out.

*Identifying issue in the kernel source*:
The issue is in this section of code (in net/ipv4/igmp.c), which is called when
an IGMP query is received  (from mainline 2.6.36-rc3 gitweb):
 ...
A IGMPv3 query has a length >= 12 and no sources.  This routine will exit after
line 880, setting the general query timer (random timeout between 0 and query
response time).  This calls igmp_gq_timer_expire():
...
.. which only sends a v3 response.  So if a v3 query is received, the kernel
always sends a v3 response.

IGMP queries happen once every 60 sec (per vlan), so the traffic is low.  A
IGMPv3 query *is* a strict superset of a IGMPv2 query, so this patch properly
short circuit's the v3 behaviour.

One issue is that this does not address force_igmp_version=1.  Then again, I've
never seen any IGMPv1 multicast equipment in the wild.  However there is a lot
of v2-only equipment. If it's necessary to support the IGMPv1 case as well:

837         if (len == 8 || IGMP_V2_SEEN(in_dev) || IGMP_V1_SEEN(in_dev)) {
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Smatch complains because we check whether "pch->chan" is NULL and then
dereference it unconditionally on the next line.  Partly the reason this
bug was introduced is because code was too complicated.  I've simplified
it a little.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The members of struct llc_sock are unsigned so if we pass a negative
value for "opt" it can cause a sign bug.  Also it can cause an integer
overflow when we multiply "opt * HZ".

CC: stable@kernel.org
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The list_head conversion unearther an unnecessary flow
check.  Since flow is always NULL here we don't need to
see if a matching flow exists already.
Reported-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>