<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/fs, branch v3.4.95</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>nfsd: check passed socket's net matches NFSd superblock's one</title>
<updated>2014-06-11T19:04:19+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2014-02-26T13:50:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a6d5f5393d055ba302edf4c59e6bfcee8b8892db'/>
<id>a6d5f5393d055ba302edf4c59e6bfcee8b8892db</id>
<content type='text'>
commit 3064639423c48d6e0eb9ecc27c512a58e38c6c57 upstream.

There could be a case, when NFSd file system is mounted in network, different
to socket's one, like below:

"ip netns exec" creates new network and mount namespace, which duplicates NFSd
mount point, created in init_net context. And thus NFS server stop in nested
network context leads to RPCBIND client destruction in init_net.
Then, on NFSd start in nested network context, rpc.nfsd process creates socket
in nested net and passes it into "write_ports", which leads to RPCBIND sockets
creation in init_net context because of the same reason (NFSd monut point was
created in init_net context). An attempt to register passed socket in nested
net leads to panic, because no RPCBIND client present in nexted network
namespace.

This patch add check that passed socket's net matches NFSd superblock's one.
And returns -EINVAL error to user psace otherwise.

v2: Put socket on exit.

Reported-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 3064639423c48d6e0eb9ecc27c512a58e38c6c57 upstream.

There could be a case, when NFSd file system is mounted in network, different
to socket's one, like below:

"ip netns exec" creates new network and mount namespace, which duplicates NFSd
mount point, created in init_net context. And thus NFS server stop in nested
network context leads to RPCBIND client destruction in init_net.
Then, on NFSd start in nested network context, rpc.nfsd process creates socket
in nested net and passes it into "write_ports", which leads to RPCBIND sockets
creation in init_net context because of the same reason (NFSd monut point was
created in init_net context). An attempt to register passed socket in nested
net leads to panic, because no RPCBIND client present in nexted network
namespace.

This patch add check that passed socket's net matches NFSd superblock's one.
And returns -EINVAL error to user psace otherwise.

v2: Put socket on exit.

Reported-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: containerize NFSd filesystem</title>
<updated>2014-06-11T19:04:19+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2013-02-01T12:56:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6c14fee44389ab182ceab1df8fecbf2ffeb3a641'/>
<id>6c14fee44389ab182ceab1df8fecbf2ffeb3a641</id>
<content type='text'>
note: this backport is just for the null pointer problem when
start nfsd in none init netns. The nfsd is still not containerized.

commit 11f779421a39b86da8a523d97e5fd3477878d44f upstream.

This patch makes NFSD file system superblock to be created per net.
This makes possible to get proper network namespace from superblock instead of
using hard-coded "init_net".

Note: NFSd fs super-block holds network namespace. This garantees, that
network namespace won't disappear from underneath of it.
This, obviously, means, that in case of kill of a container's "init" (which is not a mount
namespace, but network namespace creator) netowrk namespace won't be
destroyed.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - export cache not per netns
 - NFSD service structure not per netns]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
note: this backport is just for the null pointer problem when
start nfsd in none init netns. The nfsd is still not containerized.

commit 11f779421a39b86da8a523d97e5fd3477878d44f upstream.

This patch makes NFSD file system superblock to be created per net.
This makes possible to get proper network namespace from superblock instead of
using hard-coded "init_net".

Note: NFSd fs super-block holds network namespace. This garantees, that
network namespace won't disappear from underneath of it.
This, obviously, means, that in case of kill of a container's "init" (which is not a mount
namespace, but network namespace creator) netowrk namespace won't be
destroyed.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - export cache not per netns
 - NFSD service structure not per netns]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass proper net to nfsd_destroy() from NFSd kthreads</title>
<updated>2014-06-11T19:04:19+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-06T15:34:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=fa16ac16fc1dfe1ddca4b4c9ce71aea73a878402'/>
<id>fa16ac16fc1dfe1ddca4b4c9ce71aea73a878402</id>
<content type='text'>
commit 88c47666171989ed4c5b1a5687df09511e8c5e35 upstream.

Since NFSd service is per-net now, we have to pass proper network
context in nfsd_shutdown() from NFSd kthreads.

The simplest way I found is to get proper net from one of transports
with permanent sockets.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 88c47666171989ed4c5b1a5687df09511e8c5e35 upstream.

Since NFSd service is per-net now, we have to pass proper network
context in nfsd_shutdown() from NFSd kthreads.

The simplest way I found is to get proper net from one of transports
with permanent sockets.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass net to __write_ports() and down</title>
<updated>2014-06-11T19:04:19+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-10T09:19:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7bdac1ecae1aed95cfb922bb7c875d6a4cd04f47'/>
<id>7bdac1ecae1aed95cfb922bb7c875d6a4cd04f47</id>
<content type='text'>
commit 081603520b25f7b35ef63a363376a17c36ef74ed upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - add net_ns parameter to __write_ports_delxprt()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 081603520b25f7b35ef63a363376a17c36ef74ed upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - add net_ns parameter to __write_ports_delxprt()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass net to nfsd_set_nrthreads()</title>
<updated>2014-06-11T19:04:19+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-10T09:19:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=044b2114e85758b0afee70dd4a3f61cde45bcb32'/>
<id>044b2114e85758b0afee70dd4a3f61cde45bcb32</id>
<content type='text'>
commit 3938a0d5eb5effcc89c6909741403f4e6a37252d upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 3938a0d5eb5effcc89c6909741403f4e6a37252d upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass net to nfsd_svc()</title>
<updated>2014-06-11T19:04:19+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-10T09:19:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b282713737acd21f6f921deb2eb78538c0932a7c'/>
<id>b282713737acd21f6f921deb2eb78538c0932a7c</id>
<content type='text'>
commit d41a9417cd89a69f58a26935034b4264a2d882d6 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - one more parameter(int port) for nfsd_svc()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit d41a9417cd89a69f58a26935034b4264a2d882d6 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - one more parameter(int port) for nfsd_svc()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass net to nfsd_create_serv()</title>
<updated>2014-06-11T19:04:18+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-10T09:19:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e42e08687cd3eea10a6b43f70a4e3b0375030737'/>
<id>e42e08687cd3eea10a6b43f70a4e3b0375030737</id>
<content type='text'>
commit 6777436b0f072fb20a025a73e9b67a35ad8a5451 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 6777436b0f072fb20a025a73e9b67a35ad8a5451 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4: adjust context]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass net to nfsd_startup() and nfsd_shutdown()</title>
<updated>2014-06-11T19:04:18+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-10T09:19:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=4851433beb66690843ac042d947d1a0ade76873f'/>
<id>4851433beb66690843ac042d947d1a0ade76873f</id>
<content type='text'>
commit db42d1a76a8dfcaba7a2dc9c591fa4e231db22b3 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - one more parameter(int port) for nfsd_startup()
 - no net ns initialization in nfsd_shutdown()
 - pass @net to lockd_up() in nfsd_startup()
 - pass @net to lockd_down() in nfsd_shutdown()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit db42d1a76a8dfcaba7a2dc9c591fa4e231db22b3 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - one more parameter(int port) for nfsd_startup()
 - no net ns initialization in nfsd_shutdown()
 - pass @net to lockd_up() in nfsd_startup()
 - pass @net to lockd_down() in nfsd_shutdown()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: pass net to nfsd_init_socks()</title>
<updated>2014-06-11T19:04:18+00:00</updated>
<author>
<name>Stanislav Kinsbursky</name>
<email>skinsbursky@parallels.com</email>
</author>
<published>2012-12-10T09:19:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=0e0feda118a2394ff75068b2da3b80f467dff77f'/>
<id>0e0feda118a2394ff75068b2da3b80f467dff77f</id>
<content type='text'>
commit db6e182c17cb1a7069f7f8924721ce58ac05d9a3 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - one more parameter(int port) for nfsd_init_socks()
 - net initialization in nfsd_startup()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit db6e182c17cb1a7069f7f8924721ce58ac05d9a3 upstream.

Precursor patch. Hard-coded "init_net" will be replaced by proper one in
future.

Signed-off-by: Stanislav Kinsbursky &lt;skinsbursky@parallels.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[wengmeiling: backport to 3.4:
 - adjust context
 - one more parameter(int port) for nfsd_init_socks()
 - net initialization in nfsd_startup()]
Signed-off-by: Weng Meiling &lt;wengmeiling.weng@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nfsd: nfsd_open: when dentry_open returns an error do not propagate as struct file</title>
<updated>2014-06-07T23:02:05+00:00</updated>
<author>
<name>Harshula Jayasuriya</name>
<email>harshula@redhat.com</email>
</author>
<published>2013-07-23T04:21:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=4834ca940bf17fd203487ad93b69276ebff49688'/>
<id>4834ca940bf17fd203487ad93b69276ebff49688</id>
<content type='text'>
commit e4daf1ffbe6cc3b12aab4d604e627829e93e9914 upstream.

The following call chain:
------------------------------------------------------------
nfs4_get_vfs_file
- nfsd_open
  - dentry_open
    - do_dentry_open
      - __get_file_write_access
        - get_write_access
          - return atomic_inc_unless_negative(&amp;inode-&gt;i_writecount) ? 0 : -ETXTBSY;
------------------------------------------------------------

can result in the following state:
------------------------------------------------------------
struct nfs4_file {
...
  fi_fds = {0xffff880c1fa65c80, 0xffffffffffffffe6, 0x0},
  fi_access = {{
      counter = 0x1
    }, {
      counter = 0x0
    }},
...
------------------------------------------------------------

1) First time around, in nfs4_get_vfs_file() fp-&gt;fi_fds[O_WRONLY] is
NULL, hence nfsd_open() is called where we get status set to an error
and fp-&gt;fi_fds[O_WRONLY] to -ETXTBSY. Thus we do not reach
nfs4_file_get_access() and fi_access[O_WRONLY] is not incremented.

2) Second time around, in nfs4_get_vfs_file() fp-&gt;fi_fds[O_WRONLY] is
NOT NULL (-ETXTBSY), so nfsd_open() is NOT called, but
nfs4_file_get_access() IS called and fi_access[O_WRONLY] is incremented.
Thus we leave a landmine in the form of the nfs4_file data structure in
an incorrect state.

3) Eventually, when __nfs4_file_put_access() is called it finds
fi_access[O_WRONLY] being non-zero, it decrements it and calls
nfs4_file_put_fd() which tries to fput -ETXTBSY.
------------------------------------------------------------
...
     [exception RIP: fput+0x9]
     RIP: ffffffff81177fa9  RSP: ffff88062e365c90  RFLAGS: 00010282
     RAX: ffff880c2b3d99cc  RBX: ffff880c2b3d9978  RCX: 0000000000000002
     RDX: dead000000100101  RSI: 0000000000000001  RDI: ffffffffffffffe6
     RBP: ffff88062e365c90   R8: ffff88041fe797d8   R9: ffff88062e365d58
     R10: 0000000000000008  R11: 0000000000000000  R12: 0000000000000001
     R13: 0000000000000007  R14: 0000000000000000  R15: 0000000000000000
     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
  #9 [ffff88062e365c98] __nfs4_file_put_access at ffffffffa0562334 [nfsd]
 #10 [ffff88062e365cc8] nfs4_file_put_access at ffffffffa05623ab [nfsd]
 #11 [ffff88062e365ce8] free_generic_stateid at ffffffffa056634d [nfsd]
 #12 [ffff88062e365d18] release_open_stateid at ffffffffa0566e4b [nfsd]
 #13 [ffff88062e365d38] nfsd4_close at ffffffffa0567401 [nfsd]
 #14 [ffff88062e365d88] nfsd4_proc_compound at ffffffffa0557f28 [nfsd]
 #15 [ffff88062e365dd8] nfsd_dispatch at ffffffffa054543e [nfsd]
 #16 [ffff88062e365e18] svc_process_common at ffffffffa04ba5a4 [sunrpc]
 #17 [ffff88062e365e98] svc_process at ffffffffa04babe0 [sunrpc]
 #18 [ffff88062e365eb8] nfsd at ffffffffa0545b62 [nfsd]
 #19 [ffff88062e365ee8] kthread at ffffffff81090886
 #20 [ffff88062e365f48] kernel_thread at ffffffff8100c14a
------------------------------------------------------------


Signed-off-by: Harshula Jayasuriya &lt;harshula@redhat.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[xr: Backported to 3.4: adjust context]
Signed-off-by: Rui Xiang &lt;rui.xiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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commit e4daf1ffbe6cc3b12aab4d604e627829e93e9914 upstream.

The following call chain:
------------------------------------------------------------
nfs4_get_vfs_file
- nfsd_open
  - dentry_open
    - do_dentry_open
      - __get_file_write_access
        - get_write_access
          - return atomic_inc_unless_negative(&amp;inode-&gt;i_writecount) ? 0 : -ETXTBSY;
------------------------------------------------------------

can result in the following state:
------------------------------------------------------------
struct nfs4_file {
...
  fi_fds = {0xffff880c1fa65c80, 0xffffffffffffffe6, 0x0},
  fi_access = {{
      counter = 0x1
    }, {
      counter = 0x0
    }},
...
------------------------------------------------------------

1) First time around, in nfs4_get_vfs_file() fp-&gt;fi_fds[O_WRONLY] is
NULL, hence nfsd_open() is called where we get status set to an error
and fp-&gt;fi_fds[O_WRONLY] to -ETXTBSY. Thus we do not reach
nfs4_file_get_access() and fi_access[O_WRONLY] is not incremented.

2) Second time around, in nfs4_get_vfs_file() fp-&gt;fi_fds[O_WRONLY] is
NOT NULL (-ETXTBSY), so nfsd_open() is NOT called, but
nfs4_file_get_access() IS called and fi_access[O_WRONLY] is incremented.
Thus we leave a landmine in the form of the nfs4_file data structure in
an incorrect state.

3) Eventually, when __nfs4_file_put_access() is called it finds
fi_access[O_WRONLY] being non-zero, it decrements it and calls
nfs4_file_put_fd() which tries to fput -ETXTBSY.
------------------------------------------------------------
...
     [exception RIP: fput+0x9]
     RIP: ffffffff81177fa9  RSP: ffff88062e365c90  RFLAGS: 00010282
     RAX: ffff880c2b3d99cc  RBX: ffff880c2b3d9978  RCX: 0000000000000002
     RDX: dead000000100101  RSI: 0000000000000001  RDI: ffffffffffffffe6
     RBP: ffff88062e365c90   R8: ffff88041fe797d8   R9: ffff88062e365d58
     R10: 0000000000000008  R11: 0000000000000000  R12: 0000000000000001
     R13: 0000000000000007  R14: 0000000000000000  R15: 0000000000000000
     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
  #9 [ffff88062e365c98] __nfs4_file_put_access at ffffffffa0562334 [nfsd]
 #10 [ffff88062e365cc8] nfs4_file_put_access at ffffffffa05623ab [nfsd]
 #11 [ffff88062e365ce8] free_generic_stateid at ffffffffa056634d [nfsd]
 #12 [ffff88062e365d18] release_open_stateid at ffffffffa0566e4b [nfsd]
 #13 [ffff88062e365d38] nfsd4_close at ffffffffa0567401 [nfsd]
 #14 [ffff88062e365d88] nfsd4_proc_compound at ffffffffa0557f28 [nfsd]
 #15 [ffff88062e365dd8] nfsd_dispatch at ffffffffa054543e [nfsd]
 #16 [ffff88062e365e18] svc_process_common at ffffffffa04ba5a4 [sunrpc]
 #17 [ffff88062e365e98] svc_process at ffffffffa04babe0 [sunrpc]
 #18 [ffff88062e365eb8] nfsd at ffffffffa0545b62 [nfsd]
 #19 [ffff88062e365ee8] kthread at ffffffff81090886
 #20 [ffff88062e365f48] kernel_thread at ffffffff8100c14a
------------------------------------------------------------


Signed-off-by: Harshula Jayasuriya &lt;harshula@redhat.com&gt;
Signed-off-by: J. Bruce Fields &lt;bfields@redhat.com&gt;
[xr: Backported to 3.4: adjust context]
Signed-off-by: Rui Xiang &lt;rui.xiang@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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