<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/include/uapi/linux, branch v4.11-rc7</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input</title>
<updated>2017-04-15T00:51:16+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-04-15T00:51:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1bf4b1268e66d9364fc6fd41f906bc01458530ac'/>
<id>1bf4b1268e66d9364fc6fd41f906bc01458530ac</id>
<content type='text'>
Pull input fixes from Dmitry Torokhov:
 "Just a small update to xpad driver to recognize yet another gamepad,
  and another change making sure userio.h is exported"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: xpad - add support for Razer Wildcat gamepad
  uapi: add missing install of userio.h
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull input fixes from Dmitry Torokhov:
 "Just a small update to xpad driver to recognize yet another gamepad,
  and another change making sure userio.h is exported"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: xpad - add support for Razer Wildcat gamepad
  uapi: add missing install of userio.h
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost</title>
<updated>2017-04-14T15:49:39+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-04-14T15:49:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=787393338557456d2ad2dd49c45080624e39cbe5'/>
<id>787393338557456d2ad2dd49c45080624e39cbe5</id>
<content type='text'>
Pull virtio fixes from Michael S. Tsirkin:
 "virtio oops fixes

  The virtio pci rework using shared interrupts caused a lot of issues.
  We tried to fix them but run out of time. Revert for now, and revisit
  the issue for the next kernel.

  Luckily we are able to do this without loosing automatic interrupt
  NUMA affinity which was the main motivator for the rework"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio-pci: Remove affinity hint before freeing the interrupt
  Revert "virtio_pci: remove struct virtio_pci_vq_info"
  Revert "virtio_pci: use shared interrupts for virtqueues"
  Revert "virtio_pci: don't duplicate the msix_enable flag in struct pci_dev"
  Revert "virtio_pci: simplify MSI-X setup"
  Revert "virtio_pci: fix out of bound access for msix_names"
  MAINTAINERS: fix virtio file pattern
  virtio_console: fix uninitialized variable use
  virtio_net: clear MTU when out of range
  virtio: allow drivers to validate features
  virtio_net: enable big packets for large MTU values
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull virtio fixes from Michael S. Tsirkin:
 "virtio oops fixes

  The virtio pci rework using shared interrupts caused a lot of issues.
  We tried to fix them but run out of time. Revert for now, and revisit
  the issue for the next kernel.

  Luckily we are able to do this without loosing automatic interrupt
  NUMA affinity which was the main motivator for the rework"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio-pci: Remove affinity hint before freeing the interrupt
  Revert "virtio_pci: remove struct virtio_pci_vq_info"
  Revert "virtio_pci: use shared interrupts for virtqueues"
  Revert "virtio_pci: don't duplicate the msix_enable flag in struct pci_dev"
  Revert "virtio_pci: simplify MSI-X setup"
  Revert "virtio_pci: fix out of bound access for msix_names"
  MAINTAINERS: fix virtio file pattern
  virtio_console: fix uninitialized variable use
  virtio_net: clear MTU when out of range
  virtio: allow drivers to validate features
  virtio_net: enable big packets for large MTU values
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "virtio_pci: don't duplicate the msix_enable flag in struct pci_dev"</title>
<updated>2017-04-10T21:28:41+00:00</updated>
<author>
<name>Michael S. Tsirkin</name>
<email>mst@redhat.com</email>
</author>
<published>2017-04-04T18:09:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2008c1544c73d5190f81ef1790fa5bd2fade5bd0'/>
<id>2008c1544c73d5190f81ef1790fa5bd2fade5bd0</id>
<content type='text'>
This reverts commit 53a020c661741f3b87ad3ac6fa545088aaebac9b.

The cleanup seems to be one of the changes that broke
hybernation for some users. We are still not sure why
but revert helps.

Tested-by: Mike Galbraith &lt;efault@gmx.de&gt;
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit 53a020c661741f3b87ad3ac6fa545088aaebac9b.

The cleanup seems to be one of the changes that broke
hybernation for some users. We are still not sure why
but revert helps.

Tested-by: Mike Galbraith &lt;efault@gmx.de&gt;
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>statx: Include a mask for stx_attributes in struct statx</title>
<updated>2017-04-03T05:06:00+00:00</updated>
<author>
<name>David Howells</name>
<email>dhowells@redhat.com</email>
</author>
<published>2017-03-31T17:32:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3209f68b3ca4667069923a325c88b21131bfdf9f'/>
<id>3209f68b3ca4667069923a325c88b21131bfdf9f</id>
<content type='text'>
Include a mask in struct stat to indicate which bits of stx_attributes the
filesystem actually supports.

This would also be useful if we add another system call that allows you to
do a 'bulk attribute set' and pass in a statx struct with the masks
appropriately set to say what you want to set.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Include a mask in struct stat to indicate which bits of stx_attributes the
filesystem actually supports.

This would also be useful if we add another system call that allows you to
do a 'bulk attribute set' and pass in a statx struct with the masks
appropriately set to say what you want to set.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>statx: Reserve the top bit of the mask for future struct expansion</title>
<updated>2017-04-03T05:05:59+00:00</updated>
<author>
<name>David Howells</name>
<email>dhowells@redhat.com</email>
</author>
<published>2017-03-31T17:32:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=47071aee6a1956524b9929b3b821f6d2f8cae23c'/>
<id>47071aee6a1956524b9929b3b821f6d2f8cae23c</id>
<content type='text'>
Reserve the top bit of the mask for future expansion of the statx struct
and give an error if statx() sees it set.  All the other bits are ignored
if we see them set but don't support the bit; we just clear the bit in the
returned mask.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Reserve the top bit of the mask for future expansion of the statx struct
and give an error if statx() sees it set.  All the other bits are ignored
if we see them set but don't support the bit; we just clear the bit in the
returned mask.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>uapi: add missing install of userio.h</title>
<updated>2017-03-25T06:06:39+00:00</updated>
<author>
<name>Naohiro Aota</name>
<email>naota@elisp.net</email>
</author>
<published>2017-03-25T06:04:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5659495a7a1455665ce1466d156597ad1bda8772'/>
<id>5659495a7a1455665ce1466d156597ad1bda8772</id>
<content type='text'>
While commit 5523662edd4f ("Input: add userio module") added userio.h
under the uapi/ directory, it forgot to add the header file to Kbuild.
Thus, the file was missing from header installation.

Signed-off-by: Naohiro Aota &lt;naota@elisp.net&gt;
Reviewed-by: Lyude Paul &lt;thatslyude@gmail.com&gt;
Signed-off-by: Dmitry Torokhov &lt;dmitry.torokhov@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
While commit 5523662edd4f ("Input: add userio module") added userio.h
under the uapi/ directory, it forgot to add the header file to Kbuild.
Thus, the file was missing from header installation.

Signed-off-by: Naohiro Aota &lt;naota@elisp.net&gt;
Reviewed-by: Lyude Paul &lt;thatslyude@gmail.com&gt;
Signed-off-by: Dmitry Torokhov &lt;dmitry.torokhov@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs</title>
<updated>2017-03-23T18:39:33+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-03-23T18:39:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=131fbf4f9c096adadde27ad4bc70ea1632d720a4'/>
<id>131fbf4f9c096adadde27ad4bc70ea1632d720a4</id>
<content type='text'>
Pull btrfs fixes from Chris Mason:
 "Zygo tracked down a very old bug with inline compressed extents.

  I didn't tag this one for stable because I want to do individual
  tested backports. It's a little tricky and I'd rather do some extra
  testing on it along the way"

* 'for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  btrfs: add missing memset while reading compressed inline extents
  Btrfs: fix regression in lock_delalloc_pages
  btrfs: remove btrfs_err_str function from uapi/linux/btrfs.h
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull btrfs fixes from Chris Mason:
 "Zygo tracked down a very old bug with inline compressed extents.

  I didn't tag this one for stable because I want to do individual
  tested backports. It's a little tricky and I'd rather do some extra
  testing on it along the way"

* 'for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  btrfs: add missing memset while reading compressed inline extents
  Btrfs: fix regression in lock_delalloc_pages
  btrfs: remove btrfs_err_str function from uapi/linux/btrfs.h
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net</title>
<updated>2017-03-15T04:31:23+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-03-15T04:31:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ae50dfd61665086e617cc9e554a1285d52765670'/>
<id>ae50dfd61665086e617cc9e554a1285d52765670</id>
<content type='text'>
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-&gt;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-&gt;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
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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-&gt;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-&gt;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
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>userfaultfd: non-cooperative: rollback userfaultfd_exit</title>
<updated>2017-03-10T01:01:09+00:00</updated>
<author>
<name>Andrea Arcangeli</name>
<email>aarcange@redhat.com</email>
</author>
<published>2017-03-10T00:16:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=dd0db88d8094a6d9d4d1fc5fcd56ab619f54ccf8'/>
<id>dd0db88d8094a6d9d4d1fc5fcd56ab619f54ccf8</id>
<content type='text'>
Patch series "userfaultfd non-cooperative further update for 4.11 merge
window".

Unfortunately I noticed one relevant bug in userfaultfd_exit while doing
more testing.  I've been doing testing before and this was also tested
by kbuild bot and exercised by the selftest, but this bug never
reproduced before.

I dropped userfaultfd_exit as result.  I dropped it because of
implementation difficulty in receiving signals in __mmput and because I
think -ENOSPC as result from the background UFFDIO_COPY should be enough
already.

Before I decided to remove userfaultfd_exit, I noticed userfaultfd_exit
wasn't exercised by the selftest and when I tried to exercise it, after
moving it to a more correct place in __mmput where it would make more
sense and where the vma list is stable, it resulted in the
event_wait_completion in D state.  So then I added the second patch to
be sure even if we call userfaultfd_event_wait_completion too late
during task exit(), we won't risk to generate tasks in D state.  The
same check exists in handle_userfault() for the same reason, except it
makes a difference there, while here is just a robustness check and it's
run under WARN_ON_ONCE.

While looking at the userfaultfd_event_wait_completion() function I
looked back at its callers too while at it and I think it's not ok to
stop executing dup_fctx on the fcs list because we relay on
userfaultfd_event_wait_completion to execute
userfaultfd_ctx_put(fctx-&gt;orig) which is paired against
userfaultfd_ctx_get(fctx-&gt;orig) in dup_userfault just before
list_add(fcs).  This change only takes care of fctx-&gt;orig but this area
also needs further review looking for similar problems in fctx-&gt;new.

The only patch that is urgent is the first because it's an use after
free during a SMP race condition that affects all processes if
CONFIG_USERFAULTFD=y.  Very hard to reproduce though and probably
impossible without SLUB poisoning enabled.

This patch (of 3):

I once reproduced this oops with the userfaultfd selftest, it's not
easily reproducible and it requires SLUB poisoning to reproduce.

    general protection fault: 0000 [#1] SMP
    Modules linked in:
    CPU: 2 PID: 18421 Comm: userfaultfd Tainted: G               ------------ T 3.10.0+ #15
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
    task: ffff8801f83b9440 ti: ffff8801f833c000 task.ti: ffff8801f833c000
    RIP: 0010:[&lt;ffffffff81451299&gt;]  [&lt;ffffffff81451299&gt;] userfaultfd_exit+0x29/0xa0
    RSP: 0018:ffff8801f833fe80  EFLAGS: 00010202
    RAX: ffff8801f833ffd8 RBX: 6b6b6b6b6b6b6b6b RCX: ffff8801f83b9440
    RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8800baf18600
    RBP: ffff8801f833fee8 R08: 0000000000000000 R09: 0000000000000001
    R10: 0000000000000000 R11: ffffffff8127ceb3 R12: 0000000000000000
    R13: ffff8800baf186b0 R14: ffff8801f83b99f8 R15: 00007faed746c700
    FS:  0000000000000000(0000) GS:ffff88023fc80000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
    CR2: 00007faf0966f028 CR3: 0000000001bc6000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    Call Trace:
      do_exit+0x297/0xd10
      SyS_exit+0x17/0x20
      tracesys+0xdd/0xe2
    Code: 00 00 66 66 66 66 90 55 48 89 e5 41 54 53 48 83 ec 58 48 8b 1f 48 85 db 75 11 eb 73 66 0f 1f 44 00 00 48 8b 5b 10 48 85 db 74 64 &lt;4c&gt; 8b a3 b8 00 00 00 4d 85 e4 74 eb 41 f6 84 24 2c 01 00 00 80
    RIP  [&lt;ffffffff81451299&gt;] userfaultfd_exit+0x29/0xa0
     RSP &lt;ffff8801f833fe80&gt;
    ---[ end trace 9fecd6dcb442846a ]---

In the debugger I located the "mm" pointer in the stack and walking
mm-&gt;mmap-&gt;vm_next through the end shows the vma-&gt;vm_next list is fully
consistent and it is null terminated list as expected.  So this has to
be an SMP race condition where userfaultfd_exit was running while the
vma list was being modified by another CPU.

When userfaultfd_exit() run one of the -&gt;vm_next pointers pointed to
SLAB_POISON (RBX is the vma pointer and is 0x6b6b..).

The reason is that it's not running in __mmput but while there are still
other threads running and it's not holding the mmap_sem (it can't as it
has to wait the even to be received by the manager).  So this is an use
after free that was happening for all processes.

One more implementation problem aside from the race condition:
userfaultfd_exit has really to check a flag in mm-&gt;flags before walking
the vma or it's going to slowdown the exit() path for regular tasks.

One more implementation problem: at that point signals can't be
delivered so it would also create a task in D state if the manager
doesn't read the event.

The major design issue: it overall looks superfluous as the manager can
check for -ENOSPC in the background transfer:

	if (mmget_not_zero(ctx-&gt;mm)) {
[..]
	} else {
		return -ENOSPC;
	}

It's safer to roll it back and re-introduce it later if at all.

[rppt@linux.vnet.ibm.com: documentation fixup after removal of UFFD_EVENT_EXIT]
  Link: http://lkml.kernel.org/r/1488345437-4364-1-git-send-email-rppt@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20170224181957.19736-2-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Signed-off-by: Mike Rapoport &lt;rppt@linux.vnet.ibm.com&gt;
Acked-by: Mike Rapoport &lt;rppt@linux.vnet.ibm.com&gt;
Cc: "Dr. David Alan Gilbert" &lt;dgilbert@redhat.com&gt;
Cc: Mike Kravetz &lt;mike.kravetz@oracle.com&gt;
Cc: Pavel Emelyanov &lt;xemul@parallels.com&gt;
Cc: Hillf Danton &lt;hillf.zj@alibaba-inc.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "userfaultfd non-cooperative further update for 4.11 merge
window".

Unfortunately I noticed one relevant bug in userfaultfd_exit while doing
more testing.  I've been doing testing before and this was also tested
by kbuild bot and exercised by the selftest, but this bug never
reproduced before.

I dropped userfaultfd_exit as result.  I dropped it because of
implementation difficulty in receiving signals in __mmput and because I
think -ENOSPC as result from the background UFFDIO_COPY should be enough
already.

Before I decided to remove userfaultfd_exit, I noticed userfaultfd_exit
wasn't exercised by the selftest and when I tried to exercise it, after
moving it to a more correct place in __mmput where it would make more
sense and where the vma list is stable, it resulted in the
event_wait_completion in D state.  So then I added the second patch to
be sure even if we call userfaultfd_event_wait_completion too late
during task exit(), we won't risk to generate tasks in D state.  The
same check exists in handle_userfault() for the same reason, except it
makes a difference there, while here is just a robustness check and it's
run under WARN_ON_ONCE.

While looking at the userfaultfd_event_wait_completion() function I
looked back at its callers too while at it and I think it's not ok to
stop executing dup_fctx on the fcs list because we relay on
userfaultfd_event_wait_completion to execute
userfaultfd_ctx_put(fctx-&gt;orig) which is paired against
userfaultfd_ctx_get(fctx-&gt;orig) in dup_userfault just before
list_add(fcs).  This change only takes care of fctx-&gt;orig but this area
also needs further review looking for similar problems in fctx-&gt;new.

The only patch that is urgent is the first because it's an use after
free during a SMP race condition that affects all processes if
CONFIG_USERFAULTFD=y.  Very hard to reproduce though and probably
impossible without SLUB poisoning enabled.

This patch (of 3):

I once reproduced this oops with the userfaultfd selftest, it's not
easily reproducible and it requires SLUB poisoning to reproduce.

    general protection fault: 0000 [#1] SMP
    Modules linked in:
    CPU: 2 PID: 18421 Comm: userfaultfd Tainted: G               ------------ T 3.10.0+ #15
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
    task: ffff8801f83b9440 ti: ffff8801f833c000 task.ti: ffff8801f833c000
    RIP: 0010:[&lt;ffffffff81451299&gt;]  [&lt;ffffffff81451299&gt;] userfaultfd_exit+0x29/0xa0
    RSP: 0018:ffff8801f833fe80  EFLAGS: 00010202
    RAX: ffff8801f833ffd8 RBX: 6b6b6b6b6b6b6b6b RCX: ffff8801f83b9440
    RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8800baf18600
    RBP: ffff8801f833fee8 R08: 0000000000000000 R09: 0000000000000001
    R10: 0000000000000000 R11: ffffffff8127ceb3 R12: 0000000000000000
    R13: ffff8800baf186b0 R14: ffff8801f83b99f8 R15: 00007faed746c700
    FS:  0000000000000000(0000) GS:ffff88023fc80000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
    CR2: 00007faf0966f028 CR3: 0000000001bc6000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    Call Trace:
      do_exit+0x297/0xd10
      SyS_exit+0x17/0x20
      tracesys+0xdd/0xe2
    Code: 00 00 66 66 66 66 90 55 48 89 e5 41 54 53 48 83 ec 58 48 8b 1f 48 85 db 75 11 eb 73 66 0f 1f 44 00 00 48 8b 5b 10 48 85 db 74 64 &lt;4c&gt; 8b a3 b8 00 00 00 4d 85 e4 74 eb 41 f6 84 24 2c 01 00 00 80
    RIP  [&lt;ffffffff81451299&gt;] userfaultfd_exit+0x29/0xa0
     RSP &lt;ffff8801f833fe80&gt;
    ---[ end trace 9fecd6dcb442846a ]---

In the debugger I located the "mm" pointer in the stack and walking
mm-&gt;mmap-&gt;vm_next through the end shows the vma-&gt;vm_next list is fully
consistent and it is null terminated list as expected.  So this has to
be an SMP race condition where userfaultfd_exit was running while the
vma list was being modified by another CPU.

When userfaultfd_exit() run one of the -&gt;vm_next pointers pointed to
SLAB_POISON (RBX is the vma pointer and is 0x6b6b..).

The reason is that it's not running in __mmput but while there are still
other threads running and it's not holding the mmap_sem (it can't as it
has to wait the even to be received by the manager).  So this is an use
after free that was happening for all processes.

One more implementation problem aside from the race condition:
userfaultfd_exit has really to check a flag in mm-&gt;flags before walking
the vma or it's going to slowdown the exit() path for regular tasks.

One more implementation problem: at that point signals can't be
delivered so it would also create a task in D state if the manager
doesn't read the event.

The major design issue: it overall looks superfluous as the manager can
check for -ENOSPC in the background transfer:

	if (mmget_not_zero(ctx-&gt;mm)) {
[..]
	} else {
		return -ENOSPC;
	}

It's safer to roll it back and re-introduce it later if at all.

[rppt@linux.vnet.ibm.com: documentation fixup after removal of UFFD_EVENT_EXIT]
  Link: http://lkml.kernel.org/r/1488345437-4364-1-git-send-email-rppt@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20170224181957.19736-2-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Signed-off-by: Mike Rapoport &lt;rppt@linux.vnet.ibm.com&gt;
Acked-by: Mike Rapoport &lt;rppt@linux.vnet.ibm.com&gt;
Cc: "Dr. David Alan Gilbert" &lt;dgilbert@redhat.com&gt;
Cc: Mike Kravetz &lt;mike.kravetz@oracle.com&gt;
Cc: Pavel Emelyanov &lt;xemul@parallels.com&gt;
Cc: Hillf Danton &lt;hillf.zj@alibaba-inc.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>uapi: fix linux/packet_diag.h userspace compilation error</title>
<updated>2017-03-09T21:22:28+00:00</updated>
<author>
<name>Dmitry V. Levin</name>
<email>ldv@altlinux.org</email>
</author>
<published>2017-03-07T20:50:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=745cb7f8a5de0805cade3de3991b7a95317c7c73'/>
<id>745cb7f8a5de0805cade3de3991b7a95317c7c73</id>
<content type='text'>
Replace MAX_ADDR_LEN with its numeric value to fix the following
linux/packet_diag.h userspace compilation error:

/usr/include/linux/packet_diag.h:67:17: error: 'MAX_ADDR_LEN' undeclared here (not in a function)
  __u8 pdmc_addr[MAX_ADDR_LEN];

This is not the first case in the UAPI where the numeric value
of MAX_ADDR_LEN is used instead of symbolic one, uapi/linux/if_link.h
already does the same:

$ grep MAX_ADDR_LEN include/uapi/linux/if_link.h
	__u8 mac[32]; /* MAX_ADDR_LEN */

There are no UAPI headers besides these two that use MAX_ADDR_LEN.

Signed-off-by: Dmitry V. Levin &lt;ldv@altlinux.org&gt;
Acked-by: Pavel Emelyanov &lt;xemul@virtuozzo.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replace MAX_ADDR_LEN with its numeric value to fix the following
linux/packet_diag.h userspace compilation error:

/usr/include/linux/packet_diag.h:67:17: error: 'MAX_ADDR_LEN' undeclared here (not in a function)
  __u8 pdmc_addr[MAX_ADDR_LEN];

This is not the first case in the UAPI where the numeric value
of MAX_ADDR_LEN is used instead of symbolic one, uapi/linux/if_link.h
already does the same:

$ grep MAX_ADDR_LEN include/uapi/linux/if_link.h
	__u8 mac[32]; /* MAX_ADDR_LEN */

There are no UAPI headers besides these two that use MAX_ADDR_LEN.

Signed-off-by: Dmitry V. Levin &lt;ldv@altlinux.org&gt;
Acked-by: Pavel Emelyanov &lt;xemul@virtuozzo.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
</feed>
