get_seconds() returns real wall-clock seconds. On 32-bit systems
this value will overflow in year 2038 and beyond. This patch changes
afs_vnode record to use ktime_get_real_seconds() instead, for the
fields cb_expires and cb_expires_at.
Signed-off-by: NTina Ruchandani <ruchandani.tina@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

get_seconds() returns real wall-clock seconds. On 32-bit systems
this value will overflow in year 2038 and beyond. This patch changes
afs's vlocation record to use ktime_get_real_seconds() instead, for the
fields time_of_death and update_at.
Signed-off-by: NTina Ruchandani <ruchandani.tina@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:
"1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"
it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

The following Coccinelle semantic patch was used:
@@
@@

- rcu_assign_pointer
+ RCU_INIT_POINTER
  (..., NULL)
Signed-off-by: NAndreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:
"1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"
it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

The following Coccinelle semantic patch was used:
@@
@@

- rcu_assign_pointer
+ RCU_INIT_POINTER
  (..., NULL)
Signed-off-by: NAndreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

In AFS, mountpoints appear as symlinks with mode 0644 and normal symlinks
have mode 0777, so use this to distinguish them rather than reading the
content and parsing it.  In the case of a mountpoint, the symlink body is a
formatted string indicating the location of the target volume.

Note that with this, kAFS no longer 'pre-fetches' the contents of symlinks,
so afs_readpage() may fail with an access-denial because when the VFS calls
d_automount(), it wraps the call in an credentials override that sets the
initial creds - thereby preventing access to the caller's keyrings and the
authentication keys held therein.

To this end, a patch reverting that change to the VFS is required also.
Reported-by: NJeffrey Altman <jaltman@auristor.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Flush outstanding writes in afs when an fd is closed.  This is what NFS and
CIFS do.
Reported-by: NMarc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Handle the situation where afs_write_begin() is told to expect that a
full-page write will be made, but this doesn't happen (EFAULT, CTRL-C,
etc.), and so afs_write_end() sees a partial write took place.  Currently,
no attempt is to deal with the discrepency.

Fix this by loading the gap from the server.
Reported-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Kill struct afs_read::pg_offset as nothing uses it.  It's unnecessary as pos
can be masked off.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

When an AFS server is given an FS.FetchData{,64} request to read data from
a file, it is permitted by the protocol to return more or less than was
requested.  kafs currently relies on the latter behaviour in readpage{,s}
to handle a partial page at the end of the file (we just ask for a whole
page and clear space beyond the short read).

However, we don't handle all cases.  Add:

 (1) Handle excess data by discarding it rather than aborting.  Note that
     we use a common static buffer to discard into so that the decryption
     algorithm advances the PCBC state.

 (2) Handle a short read that affects more than just the last page.

Note that if a read comes up unexpectedly short of long, it's possible that
the server's copy of the file changed - in which case the data version
number will have been incremented and the callback will have been broken -
in which case all the pages currently attached to the inode will be zapped
anyway at some point.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Servers may send a callback array that is the same size as
the FID array, or an empty array.  If the callback count is
0, the code would attempt to read (fid_count * 12) bytes of
data, which would fail and result in an unmarshalling error.
This would lead to stale data for remotely modified files
or directories.

Store the callback array size in the internal afs_call
structure and use that to determine the amount of data to
read.
Signed-off-by: NMarc Dionne <marc.dionne@auristor.com>

Mode bits for an afs file should not be enforced in the usual
way.

For files, the absence of user bits can restrict file access
with respect to what is granted by the server.

These bits apply regardless of the owner or the current uid; the
rest of the mode bits (group, other) are ignored.
Signed-off-by: NMarc Dionne <marc.dionne@auristor.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

The group was hard coded to GLOBAL_ROOT_GID; use the group
ID that was received from the server.
Signed-off-by: NMarc Dionne <marc.dionne@auristor.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

afs_fill_page() loads the page it wants to fill into the afs_read request
without incrementing its refcount - but then calls afs_put_read() to clean
up afterwards, which then releases a ref on the page.

Fix this by getting a ref on the page before calling
afs_vnode_fetch_data().

This causes sync after a write to hang in afs_writepages_region() because
find_get_pages_tag() gets confused and doesn't return.

Fixes: 196ee9cd ("afs: Make afs_fs_fetch_data() take a list of pages")
Reported-by: NMarc Dionne <marc.dionne@auristor.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Tested-by: NMarc Dionne <marc.dionne@auristor.com>

In afs_writepages_region(), inside the loop where we find dirty pages to
deal with, one of the if-statements is missing a put_page().
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Pull block fixes from Jens Axboe:
 "Four small fixes for this cycle:

   - followup fix from Neil for a fix that went in before -rc2, ensuring
     that we always see the full per-task bio_list.

   - fix for blk-mq-sched from me that ensures that we retain similar
     direct-to-issue behavior on running the queue.

   - fix from Sagi fixing a potential NULL pointer dereference in blk-mq
     on spurious CPU unplug.

   - a memory leak fix in writeback from Tahsin, fixing a case where
     device removal of a mounted device can leak a struct
     wb_writeback_work"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
  writeback: fix memory leak in wb_queue_work()
  blk-mq: Fix tagset reinit in the presence of cpu hot-unplug
  blk: Ensure users for current->bio_list can see the full list.

Pull SCSI fixes from James Bottomley:
 "This is a rather large set of fixes. The bulk are for lpfc correcting
  a lot of issues in the new NVME driver code which just went in in the
  merge window.

  The others are:

   - fix a hang in the vmware paravirt driver caused by incorrect
     handling of the new MSI vector allocation

   - long standing bug in storvsc, which recent block changes turned
     from being a harmless annoyance into a hang

   - yet more fallout (in mpt3sas) from the changes to device blocking

  The remainder are small fixes and updates"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (34 commits)
  scsi: lpfc: Add shutdown method for kexec
  scsi: storvsc: Workaround for virtual DVD SCSI version
  scsi: lpfc: revise version number to 11.2.0.10
  scsi: lpfc: code cleanups in NVME initiator discovery
  scsi: lpfc: code cleanups in NVME initiator base
  scsi: lpfc: correct rdp diag portnames
  scsi: lpfc: remove dead sli3 nvme code
  scsi: lpfc: correct double print
  scsi: lpfc: Rename LPFC_MAX_EQ_DELAY to LPFC_MAX_EQ_DELAY_EQID_CNT
  scsi: lpfc: Rework lpfc Kconfig for NVME options
  scsi: lpfc: add transport eh_timed_out reference
  scsi: lpfc: Fix eh_deadline setting for sli3 adapters.
  scsi: lpfc: add NVME exchange aborts
  scsi: lpfc: Fix nvme allocation bug on failed nvme_fc_register_localport
  scsi: lpfc: Fix IO submission if WQ is full
  scsi: lpfc: Fix NVME CMD IU byte swapped word 1 problem
  scsi: lpfc: Fix RCTL value on NVME LS request and response
  scsi: lpfc: Fix crash during Hardware error recovery on SLI3 adapters
  scsi: lpfc: fix missing spin_unlock on sql_list_lock
  scsi: lpfc: don't dereference dma_buf->iocbq before null check
  ...

Pull gfs2 fix from Bob Peterson:
 "This is an emergency patch for 4.11-rc3

  The GFS2 developers uncovered a really nasty problem that can lead to
  random corruption and kernel panic, much like the last one. Andreas
  Gruenbacher wrote a simple one-line patch to fix the problem."

* tag 'gfs2-4.11-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Avoid alignment hole in struct lm_lockname

Pull crypto fixes from Herbert Xu:

 - self-test failure of crc32c on powerpc

 - regressions of ecb(aes) when used with xts/lrw in s5p-sss

 - a number of bugs in the omap RNG driver

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: s5p-sss - Fix spinlock recursion on LRW(AES)
  hwrng: omap - Do not access INTMASK_REG on EIP76
  hwrng: omap - use devm_clk_get() instead of of_clk_get()
  hwrng: omap - write registers after enabling the clock
  crypto: s5p-sss - Fix completing crypto request in IRQ handler
  crypto: powerpc - Fix initialisation of crc32c context

Commit 88ffbf3e switches to using rhashtables for glocks, hashing over
the entire struct lm_lockname instead of its individual fields.  On some
architectures, struct lm_lockname contains a hole of uninitialized
memory due to alignment rules, which now leads to incorrect hash values.
Get rid of that hole.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
CC: <stable@vger.kernel.org> #v4.3+

Pull networking fixes from David Miller:

 1) Ensure that mtu is at least IPV6_MIN_MTU in ipv6 VTI tunnel driver,
    from Steffen Klassert.

 2) Fix crashes when user tries to get_next_key on an LPM bpf map, from
    Alexei Starovoitov.

 3) Fix detection of VLAN fitlering feature for bnx2x VF devices, from
    Michal Schmidt.

 4) We can get a divide by zero when TCP socket are morphed into
    listening state, fix from Eric Dumazet.

 5) Fix socket refcounting bugs in skb_complete_wifi_ack() and
    skb_complete_tx_timestamp(). From Eric Dumazet.

 6) Use after free in dccp_feat_activate_values(), also from Eric
    Dumazet.

 7) Like bonding team needs to use ETH_MAX_MTU as netdev->max_mtu, from
    Jarod Wilson.

 8) Fix use after free in vrf_xmit(), from David Ahern.

 9) Don't do UDP Fragmentation Offload on IPComp ipsec packets, from
    Alexey Kodanev.

10) Properly check napi_complete_done() return value in order to decide
    whether to re-enable IRQs or not in amd-xgbe driver, from Thomas
    Lendacky.

11) Fix double free of hwmon device in marvell phy driver, from Andrew
    Lunn.

12) Don't crash on malformed netlink attributes in act_connmark, from
    Etienne Noss.

13) Don't remove routes with a higher metric in ipv6 ECMP route replace,
    from Sabrina Dubroca.

14) Don't write into a cloned SKB in ipv6 fragmentation handling, from
    Florian Westphal.

15) Fix routing redirect races in dccp and tcp, basically the ICMP
    handler can't modify the socket's cached route in it's locked by the
    user at this moment. From Jon Maxwell.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (108 commits)
  qed: Enable iSCSI Out-of-Order
  qed: Correct out-of-bound access in OOO history
  qed: Fix interrupt flags on Rx LL2
  qed: Free previous connections when releasing iSCSI
  qed: Fix mapping leak on LL2 rx flow
  qed: Prevent creation of too-big u32-chains
  qed: Align CIDs according to DORQ requirement
  mlxsw: reg: Fix SPVMLR max record count
  mlxsw: reg: Fix SPVM max record count
  net: Resend IGMP memberships upon peer notification.
  dccp: fix memory leak during tear-down of unsuccessful connection request
  tun: fix premature POLLOUT notification on tun devices
  dccp/tcp: fix routing redirect race
  ucc/hdlc: fix two little issue
  vxlan: fix ovs support
  net: use net->count to check whether a netns is alive or not
  bridge: drop netfilter fake rtable unconditionally
  ipv6: avoid write to a possibly cloned skb
  net: wimax/i2400m: fix NULL-deref at probe
  isdn/gigaset: fix NULL-deref at probe
  ...

Pull cgroup fixes from Tejun Heo:
 "Three cgroup fixes.  Nothing critical:

   - the pids controller could trigger suspicious RCU warning
     spuriously. Fixed.

   - in the debug controller, %p -> %pK to protect kernel pointer
     from getting exposed.

   - documentation formatting fix"

* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroups: censor kernel pointer in debug files
  cgroup/pids: remove spurious suspicious RCU usage warning
  cgroup: Fix indenting in PID controller documentation

Pull libata fixes from Tejun Heo:
 "Three libata fixes:

   - fix for a circular reference bug in sysfs code which prevented
     pata_legacy devices from being released after probe failure, which
     in turn prevented devres from releasing the associated resources.

   - drop spurious WARN in the command issue path which can be triggered
     by a legitimate passthrough command.

   - an ahci_qoriq specific fix"

* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  ahci: qoriq: correct the sata ecc setting error
  libata: drop WARN from protocol error in ata_sff_qc_issue()
  libata: transport: Remove circular dependency at free time

Pull workqueue fix from Tejun Heo:
 "If a delayed work is queued with NULL @wq, workqueue code explodes
  after the timer expires at which point it's difficult to tell who the
  culprit was.

  This actually happened and the offender was net/smc this time.

  Add an explicit sanity check for it in the queueing path"

* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: trigger WARN if queue_delayed_work() is called with NULL @wq

Pull percpu fixes from Tejun Heo:

 - the allocation path was updating pcpu_nr_empty_pop_pages without the
   required locking which can lead to incorrect handling of empty chunks
   (e.g. keeping too many around), which is buggy but shouldn't lead to
   critical failures. Fixed by adding the locking

 - a trivial patch to drop an unused param from pcpu_get_pages()

* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu: remove unused chunk_alloc parameter from pcpu_get_pages()
  percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages

Yuval Mintz says:

====================
qed: Fixes series

This address several different issues in qed.
The more significant portions:

Patch #1 would cause timeout when qedr utilizes the highest
CIDs availble for it [or when future qede adapters would utilize
queues in some constellations].

Patch #4 fixes a leak of mapped addresses; When iommu is enabled,
offloaded storage protocols might eventually run out of resources
and fail to map additional buffers.

Patches #6,#7 were missing in the initial iSCSI infrastructure
submissions, and would hamper qedi's stability when it reaches
out-of-order scenarios.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Missing in the initial submission, qed fails to propagate qedi's
request to enable OOO to firmware.

Fixes: fc831825 ("qed: Add support for hardware offloaded iSCSI")
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Need to set the number of entries in database, otherwise the logic
would quickly surpass the array.

Fixes: 1d6cff4f ("qed: Add iSCSI out of order packet handling")
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Before iterating over the the LL2 Rx ring, the ring's
spinlock is taken via spin_lock_irqsave().
The actual processing of the packet [including handling
by the protocol driver] is done without said lock,
so qed releases the spinlock and re-claims it afterwards.

Problem is that the final spin_lock_irqrestore() at the end
of the iteration uses the original flags saved from the
initial irqsave() instead of the flags from the most recent
irqsave(). So it's possible that the interrupt status would
be incorrect at the end of the processing.

Fixes: 0a7fb11c ("qed: Add Light L2 support");
CC: Ram Amrani <Ram.Amrani@cavium.com>
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixes: fc831825 ("qed: Add support for hardware offloaded iSCSI")
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When receiving an Rx LL2 packet, qed fails to unmap the previous buffer.

Fixes: 0a7fb11c ("qed: Add Light L2 support");
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Current Logic would allow the creation of a chain with U32_MAX + 1
elements, when the actual maximum supported by the driver infrastructure
is U32_MAX.

Fixes: a91eb52a ("qed: Revisit chain implementation")
Signed-off-by: NTomer Tayar <Tomer.Tayar@cavium.com>
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The Doorbell HW block can be configured at a granularity
of 16 x CIDs, so we need to make sure that the actual number
of CIDs configured would be a multiplication of 16.

Today, when RoCE is enabled - given that the number is unaligned,
doorbelling the higher CIDs would fail to reach the firmware and
would eventually timeout.

Fixes: dbb799c3 ("qed: Initialize hardware for new protocols")
Signed-off-by: NRam Amrani <Ram.Amrani@cavium.com>
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jiri Pirko says:

====================
mlxsw: Couple of fixes

Couple or small fixes.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The num_rec field is 8 bit, so the maximal count number is 255.
This fixes vlans learning not being enabled for wider ranges than 255.

Fixes: a4feea74 ("mlxsw: reg: Add Switch Port VLAN MAC Learning register definition")
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Reviewed-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The num_rec field is 8 bit, so the maximal count number is 255. This
fixes vlans not being enabled for wider ranges than 255.

Fixes: b2e345f9 ("mlxsw: reg: Add Switch Port VID and Switch Port VLAN Membership registers definitions")
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Reviewed-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When we notify peers of potential changes,  it's also good to update
IGMP memberships.  For example, during VM migration, updating IGMP
memberships will redirect existing multicast streams to the VM at the
new location.
Signed-off-by: NVladislav Yasevich <vyasevic@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If we have scheduling enabled, we jump directly to insert-and-run.
That's fine, but we run the queue async and we don't pass in information
on whether we can block from this context or not. Fixup both these
cases.
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This patch fixes a memory leak, which happens if the connection request
is not fulfilled between parsing the DCCP options and handling the SYN
(because e.g. the backlog is full), because we forgot to free the
list of ack vectors.
Reported-by: NJianwen Ji <jiji@redhat.com>
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

aszlig observed failing ssh tunnels (-w) during initialization since
commit cc9da6cc ("ipv6: addrconf: use stable address generator for
ARPHRD_NONE"). We already had reports that the mentioned commit breaks
Juniper VPN connections. I can't clearly say that the Juniper VPN client
has the same problem, but it is worth a try to hint to this patch.

Because of the early generation of link local addresses, the kernel now
can start asking for routers on the local subnet much earlier than usual.
Those router solicitation packets arrive inside the ssh channels and
should be transmitted to the tun fd before the configuration scripts
might have upped the interface and made it ready for transmission.

ssh polls on the interface and receives back a POLL_OUT. It tries to send
the earily router solicitation packet to the tun interface.  Unfortunately
it hasn't been up'ed yet by config scripts, thus failing with -EIO. ssh
doesn't retry again and considers the tun interface broken forever.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=121131
Fixes: cc9da6cc ("ipv6: addrconf: use stable address generator for ARPHRD_NONE")
Cc: Bjørn Mork <bjorn@mork.no>
Reported-by: NValdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Reported-by: NJonas Lippuner <jonas@lippuner.ca>
Cc: Jonas Lippuner <jonas@lippuner.ca>
Reported-by: Naszlig <aszlig@redmoonstudios.org>
Cc: aszlig <aszlig@redmoonstudios.org>
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As Eric Dumazet pointed out this also needs to be fixed in IPv6.
v2: Contains the IPv6 tcp/Ipv6 dccp patches as well.

We have seen a few incidents lately where a dst_enty has been freed
with a dangling TCP socket reference (sk->sk_dst_cache) pointing to that
dst_entry. If the conditions/timings are right a crash then ensues when the
freed dst_entry is referenced later on. A Common crashing back trace is:

 #8 [] page_fault at ffffffff8163e648
    [exception RIP: __tcp_ack_snd_check+74]
.
.
 #9 [] tcp_rcv_established at ffffffff81580b64
#10 [] tcp_v4_do_rcv at ffffffff8158b54a
#11 [] tcp_v4_rcv at ffffffff8158cd02
#12 [] ip_local_deliver_finish at ffffffff815668f4
#13 [] ip_local_deliver at ffffffff81566bd9
#14 [] ip_rcv_finish at ffffffff8156656d
#15 [] ip_rcv at ffffffff81566f06
#16 [] __netif_receive_skb_core at ffffffff8152b3a2
#17 [] __netif_receive_skb at ffffffff8152b608
#18 [] netif_receive_skb at ffffffff8152b690
#19 [] vmxnet3_rq_rx_complete at ffffffffa015eeaf [vmxnet3]
#20 [] vmxnet3_poll_rx_only at ffffffffa015f32a [vmxnet3]
#21 [] net_rx_action at ffffffff8152bac2
#22 [] __do_softirq at ffffffff81084b4f
#23 [] call_softirq at ffffffff8164845c
#24 [] do_softirq at ffffffff81016fc5
#25 [] irq_exit at ffffffff81084ee5
#26 [] do_IRQ at ffffffff81648ff8

Of course it may happen with other NIC drivers as well.

It's found the freed dst_entry here:

 224 static bool tcp_in_quickack_mode(struct sock *sk)↩
 225 {↩
 226 ▹       const struct inet_connection_sock *icsk = inet_csk(sk);↩
 227 ▹       const struct dst_entry *dst = __sk_dst_get(sk);↩
 228 ↩
 229 ▹       return (dst && dst_metric(dst, RTAX_QUICKACK)) ||↩
 230 ▹       ▹       (icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong);↩
 231 }↩

But there are other backtraces attributed to the same freed dst_entry in
netfilter code as well.

All the vmcores showed 2 significant clues:

- Remote hosts behind the default gateway had always been redirected to a
different gateway. A rtable/dst_entry will be added for that host. Making
more dst_entrys with lower reference counts. Making this more probable.

- All vmcores showed a postitive LockDroppedIcmps value, e.g:

LockDroppedIcmps                  267

A closer look at the tcp_v4_err() handler revealed that do_redirect() will run
regardless of whether user space has the socket locked. This can result in a
race condition where the same dst_entry cached in sk->sk_dst_entry can be
decremented twice for the same socket via:

do_redirect()->__sk_dst_check()-> dst_release().

Which leads to the dst_entry being prematurely freed with another socket
pointing to it via sk->sk_dst_cache and a subsequent crash.

To fix this skip do_redirect() if usespace has the socket locked. Instead let
the redirect take place later when user space does not have the socket
locked.

The dccp/IPv6 code is very similar in this respect, so fixing it there too.

As Eric Garver pointed out the following commit now invalidates routes. Which
can set the dst->obsolete flag so that ipv4_dst_check() returns null and
triggers the dst_release().

Fixes: ceb33206 ("ipv4: Kill routes during PMTU/redirect updates.")
Cc: Eric Garver <egarver@redhat.com>
Cc: Hannes Sowa <hsowa@redhat.com>
Signed-off-by: NJon Maxwell <jmaxwell37@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>