<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/fs, branch v3.18.74</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>xfs: remove kmem_zalloc_greedy</title>
<updated>2017-10-08T08:11:22+00:00</updated>
<author>
<name>Darrick J. Wong</name>
<email>darrick.wong@oracle.com</email>
</author>
<published>2017-03-06T19:58:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c9103723b7e4bd5046081c7569a73a752972cec9'/>
<id>c9103723b7e4bd5046081c7569a73a752972cec9</id>
<content type='text'>
[ Upstream commit 08b005f1333154ae5b404ca28766e0ffb9f1c150 ]

The sole remaining caller of kmem_zalloc_greedy is bulkstat, which uses
it to grab 1-4 pages for staging of inobt records.  The infinite loop in
the greedy allocation function is causing hangs[1] in generic/269, so
just get rid of the greedy allocator in favor of kmem_zalloc_large.
This makes bulkstat somewhat more likely to ENOMEM if there's really no
pages to spare, but eliminates a source of hangs.

[1] http://lkml.kernel.org/r/20170301044634.rgidgdqqiiwsmfpj%40XZHOUW.usersys.redhat.com

Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&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>
[ Upstream commit 08b005f1333154ae5b404ca28766e0ffb9f1c150 ]

The sole remaining caller of kmem_zalloc_greedy is bulkstat, which uses
it to grab 1-4 pages for staging of inobt records.  The infinite loop in
the greedy allocation function is causing hangs[1] in generic/269, so
just get rid of the greedy allocator in favor of kmem_zalloc_large.
This makes bulkstat somewhat more likely to ENOMEM if there's really no
pages to spare, but eliminates a source of hangs.

[1] http://lkml.kernel.org/r/20170301044634.rgidgdqqiiwsmfpj%40XZHOUW.usersys.redhat.com

Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>btrfs: prevent to set invalid default subvolid</title>
<updated>2017-10-05T07:35:52+00:00</updated>
<author>
<name>satoru takeuchi</name>
<email>satoru.takeuchi@gmail.com</email>
</author>
<published>2017-09-12T13:42:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=540125645c70c02e485365a259545a15571e863a'/>
<id>540125645c70c02e485365a259545a15571e863a</id>
<content type='text'>
commit 6d6d282932d1a609e60dc4467677e0e863682f57 upstream.

`btrfs sub set-default` succeeds to set an ID which isn't corresponding to any
fs/file tree. If such the bad ID is set to a filesystem, we can't mount this
filesystem without specifying `subvol` or `subvolid` mount options.

Fixes: 6ef5ed0d386b ("Btrfs: add ioctl and incompat flag to set the default mount subvol")
Signed-off-by: Satoru Takeuchi &lt;satoru.takeuchi@gmail.com&gt;
Reviewed-by: Qu Wenruo &lt;quwenruo.btrfs@gmx.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.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 6d6d282932d1a609e60dc4467677e0e863682f57 upstream.

`btrfs sub set-default` succeeds to set an ID which isn't corresponding to any
fs/file tree. If such the bad ID is set to a filesystem, we can't mount this
filesystem without specifying `subvol` or `subvolid` mount options.

Fixes: 6ef5ed0d386b ("Btrfs: add ioctl and incompat flag to set the default mount subvol")
Signed-off-by: Satoru Takeuchi &lt;satoru.takeuchi@gmail.com&gt;
Reviewed-by: Qu Wenruo &lt;quwenruo.btrfs@gmx.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>vfs: Return -ENXIO for negative SEEK_HOLE / SEEK_DATA offsets</title>
<updated>2017-10-05T07:35:52+00:00</updated>
<author>
<name>Andreas Gruenbacher</name>
<email>agruenba@redhat.com</email>
</author>
<published>2017-09-25T10:23:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9f119f5cc0480e7d1eaa4e16ecbcddcdd5e8db6f'/>
<id>9f119f5cc0480e7d1eaa4e16ecbcddcdd5e8db6f</id>
<content type='text'>
commit fc46820b27a2d9a46f7e90c9ceb4a64a1bc5fab8 upstream.

In generic_file_llseek_size, return -ENXIO for negative offsets as well
as offsets beyond EOF.  This affects filesystems which don't implement
SEEK_HOLE / SEEK_DATA internally, possibly because they don't support
holes.

Fixes xfstest generic/448.

Signed-off-by: Andreas Gruenbacher &lt;agruenba@redhat.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&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 fc46820b27a2d9a46f7e90c9ceb4a64a1bc5fab8 upstream.

In generic_file_llseek_size, return -ENXIO for negative offsets as well
as offsets beyond EOF.  This affects filesystems which don't implement
SEEK_HOLE / SEEK_DATA internally, possibly because they don't support
holes.

Fixes xfstest generic/448.

Signed-off-by: Andreas Gruenbacher &lt;agruenba@redhat.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>SMB3: Don't ignore O_SYNC/O_DSYNC and O_DIRECT flags</title>
<updated>2017-10-05T07:35:52+00:00</updated>
<author>
<name>Steve French</name>
<email>smfrench@gmail.com</email>
</author>
<published>2017-09-22T06:40:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=64304f5ae2f37d54072b208d53fb692ef941d168'/>
<id>64304f5ae2f37d54072b208d53fb692ef941d168</id>
<content type='text'>
commit 1013e760d10e614dc10b5624ce9fc41563ba2e65 upstream.

Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Reviewed-by: Pavel Shilovsky &lt;pshilov@microsoft.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 1013e760d10e614dc10b5624ce9fc41563ba2e65 upstream.

Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Reviewed-by: Pavel Shilovsky &lt;pshilov@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>SMB: Validate negotiate (to protect against downgrade) even if signing off</title>
<updated>2017-10-05T07:35:51+00:00</updated>
<author>
<name>Steve French</name>
<email>smfrench@gmail.com</email>
</author>
<published>2017-09-21T00:57:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b3c1243ba1bc4ab4c632078412381750f94bb649'/>
<id>b3c1243ba1bc4ab4c632078412381750f94bb649</id>
<content type='text'>
commit 0603c96f3af50e2f9299fa410c224ab1d465e0f9 upstream.

As long as signing is supported (ie not a guest user connection) and
connection is SMB3 or SMB3.02, then validate negotiate (protect
against man in the middle downgrade attacks).  We had been doing this
only when signing was required, not when signing was just enabled,
but this more closely matches recommended SMB3 behavior and is
better security.  Suggested by Metze.

Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Jeremy Allison &lt;jra@samba.org&gt;
Acked-by: Stefan Metzmacher &lt;metze@samba.org&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.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 0603c96f3af50e2f9299fa410c224ab1d465e0f9 upstream.

As long as signing is supported (ie not a guest user connection) and
connection is SMB3 or SMB3.02, then validate negotiate (protect
against man in the middle downgrade attacks).  We had been doing this
only when signing was required, not when signing was just enabled,
but this more closely matches recommended SMB3 behavior and is
better security.  Suggested by Metze.

Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Jeremy Allison &lt;jra@samba.org&gt;
Acked-by: Stefan Metzmacher &lt;metze@samba.org&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>cifs: release auth_key.response for reconnect.</title>
<updated>2017-10-05T07:35:50+00:00</updated>
<author>
<name>Shu Wang</name>
<email>shuwang@redhat.com</email>
</author>
<published>2017-09-08T10:48:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=456bbdc86d18d95d389cc8012259176c09211d5b'/>
<id>456bbdc86d18d95d389cc8012259176c09211d5b</id>
<content type='text'>
commit f5c4ba816315d3b813af16f5571f86c8d4e897bd upstream.

There is a race that cause cifs reconnect in cifs_mount,
- cifs_mount
  - cifs_get_tcp_session
    - [ start thread cifs_demultiplex_thread
      - cifs_read_from_socket: -ECONNABORTED
        - DELAY_WORK smb2_reconnect_server ]
  - cifs_setup_session
  - [ smb2_reconnect_server ]

auth_key.response was allocated in cifs_setup_session, and
will release when the session destoried. So when session re-
connect, auth_key.response should be check and released.

Tested with my system:
CIFS VFS: Free previous auth_key.response = ffff8800320bbf80

A simple auth_key.response allocation call trace:
- cifs_setup_session
- SMB2_sess_setup
- SMB2_sess_auth_rawntlmssp_authenticate
- build_ntlmssp_auth_blob
- setup_ntlmv2_rsp

Signed-off-by: Shu Wang &lt;shuwang@redhat.com&gt;
Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.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 f5c4ba816315d3b813af16f5571f86c8d4e897bd upstream.

There is a race that cause cifs reconnect in cifs_mount,
- cifs_mount
  - cifs_get_tcp_session
    - [ start thread cifs_demultiplex_thread
      - cifs_read_from_socket: -ECONNABORTED
        - DELAY_WORK smb2_reconnect_server ]
  - cifs_setup_session
  - [ smb2_reconnect_server ]

auth_key.response was allocated in cifs_setup_session, and
will release when the session destoried. So when session re-
connect, auth_key.response should be check and released.

Tested with my system:
CIFS VFS: Free previous auth_key.response = ffff8800320bbf80

A simple auth_key.response allocation call trace:
- cifs_setup_session
- SMB2_sess_setup
- SMB2_sess_auth_rawntlmssp_authenticate
- build_ntlmssp_auth_blob
- setup_ntlmv2_rsp

Signed-off-by: Shu Wang &lt;shuwang@redhat.com&gt;
Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>cifs: release cifs root_cred after exit_cifs</title>
<updated>2017-10-05T07:35:50+00:00</updated>
<author>
<name>Shu Wang</name>
<email>shuwang@redhat.com</email>
</author>
<published>2017-09-07T08:03:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0c317759e7805e8a615e076186108754093e6d68'/>
<id>0c317759e7805e8a615e076186108754093e6d68</id>
<content type='text'>
commit 94183331e815617246b1baa97e0916f358c794bb upstream.

memory leak was found by kmemleak. exit_cifs_spnego
should be called before cifs module removed, or
cifs root_cred will not be released.

kmemleak report:
unreferenced object 0xffff880070a3ce40 (size 192):
  backtrace:
     kmemleak_alloc+0x4a/0xa0
     kmem_cache_alloc+0xc7/0x1d0
     prepare_kernel_cred+0x20/0x120
     init_cifs_spnego+0x2d/0x170 [cifs]
     0xffffffffc07801f3
     do_one_initcall+0x51/0x1b0
     do_init_module+0x60/0x1fd
     load_module+0x161e/0x1b60
     SYSC_finit_module+0xa9/0x100
     SyS_finit_module+0xe/0x10

Signed-off-by: Shu Wang &lt;shuwang@redhat.com&gt;
Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.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 94183331e815617246b1baa97e0916f358c794bb upstream.

memory leak was found by kmemleak. exit_cifs_spnego
should be called before cifs module removed, or
cifs root_cred will not be released.

kmemleak report:
unreferenced object 0xffff880070a3ce40 (size 192):
  backtrace:
     kmemleak_alloc+0x4a/0xa0
     kmem_cache_alloc+0xc7/0x1d0
     prepare_kernel_cred+0x20/0x120
     init_cifs_spnego+0x2d/0x170 [cifs]
     0xffffffffc07801f3
     do_one_initcall+0x51/0x1b0
     do_init_module+0x60/0x1fd
     load_module+0x161e/0x1b60
     SYSC_finit_module+0xa9/0x100
     SyS_finit_module+0xe/0x10

Signed-off-by: Shu Wang &lt;shuwang@redhat.com&gt;
Signed-off-by: Steve French &lt;smfrench@gmail.com&gt;
Reviewed-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: fix incorrect quotaoff if the quota feature is enabled</title>
<updated>2017-09-27T08:57:19+00:00</updated>
<author>
<name>zhangyi (F)</name>
<email>yi.zhang@huawei.com</email>
</author>
<published>2017-08-24T19:19:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ab1717dafd8355d3a52ec94deacf806a232ad773'/>
<id>ab1717dafd8355d3a52ec94deacf806a232ad773</id>
<content type='text'>
commit b0a5a9589decd07db755d6a8d9c0910d96ff7992 upstream.

Current ext4 quota should always "usage enabled" if the
quota feautre is enabled. But in ext4_orphan_cleanup(), it
turn quotas off directly (used for the older journaled
quota), so we cannot turn it on again via "quotaon" unless
umount and remount ext4.

Simple reproduce:

  mkfs.ext4 -O project,quota /dev/vdb1
  mount -o prjquota /dev/vdb1 /mnt
  chattr -p 123 /mnt
  chattr +P /mnt
  touch /mnt/aa /mnt/bb
  exec 100&lt;&gt;/mnt/aa
  rm -f /mnt/aa
  sync
  echo c &gt; /proc/sysrq-trigger

  #reboot and mount
  mount -o prjquota /dev/vdb1 /mnt
  #query status
  quotaon -Ppv /dev/vdb1
  #output
  quotaon: Cannot find mountpoint for device /dev/vdb1
  quotaon: No correct mountpoint specified.

This patch add check for journaled quotas to avoid incorrect
quotaoff when ext4 has quota feautre.

Signed-off-by: zhangyi (F) &lt;yi.zhang@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&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 b0a5a9589decd07db755d6a8d9c0910d96ff7992 upstream.

Current ext4 quota should always "usage enabled" if the
quota feautre is enabled. But in ext4_orphan_cleanup(), it
turn quotas off directly (used for the older journaled
quota), so we cannot turn it on again via "quotaon" unless
umount and remount ext4.

Simple reproduce:

  mkfs.ext4 -O project,quota /dev/vdb1
  mount -o prjquota /dev/vdb1 /mnt
  chattr -p 123 /mnt
  chattr +P /mnt
  touch /mnt/aa /mnt/bb
  exec 100&lt;&gt;/mnt/aa
  rm -f /mnt/aa
  sync
  echo c &gt; /proc/sysrq-trigger

  #reboot and mount
  mount -o prjquota /dev/vdb1 /mnt
  #query status
  quotaon -Ppv /dev/vdb1
  #output
  quotaon: Cannot find mountpoint for device /dev/vdb1
  quotaon: No correct mountpoint specified.

This patch add check for journaled quotas to avoid incorrect
quotaoff when ext4 has quota feautre.

Signed-off-by: zhangyi (F) &lt;yi.zhang@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: check hot_data for roll-forward recovery</title>
<updated>2017-09-27T08:57:19+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2017-08-13T04:33:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=70768be91bcc00508038ee743c76fe9f404dfcf9'/>
<id>70768be91bcc00508038ee743c76fe9f404dfcf9</id>
<content type='text'>
commit 125c9fb1ccb53eb2ea9380df40f3c743f3fb2fed upstream.

We need to check HOT_DATA to truncate any previous data block when doing
roll-forward recovery.

Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&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 125c9fb1ccb53eb2ea9380df40f3c743f3fb2fed upstream.

We need to check HOT_DATA to truncate any previous data block when doing
roll-forward recovery.

Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>xfs: XFS_IS_REALTIME_INODE() should be false if no rt device present</title>
<updated>2017-09-13T21:03:47+00:00</updated>
<author>
<name>Richard Wareing</name>
<email>rwareing@fb.com</email>
</author>
<published>2017-09-12T23:09:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b766f0849a52e235268f362b7d8ec8bc36cdc7f0'/>
<id>b766f0849a52e235268f362b7d8ec8bc36cdc7f0</id>
<content type='text'>
commit b31ff3cdf540110da4572e3e29bd172087af65cc upstream.

If using a kernel with CONFIG_XFS_RT=y and we set the RHINHERIT flag on
a directory in a filesystem that does not have a realtime device and
create a new file in that directory, it gets marked as a real time file.
When data is written and a fsync is issued, the filesystem attempts to
flush a non-existent rt device during the fsync process.

This results in a crash dereferencing a null buftarg pointer in
xfs_blkdev_issue_flush():

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: xfs_blkdev_issue_flush+0xd/0x20
  .....
  Call Trace:
    xfs_file_fsync+0x188/0x1c0
    vfs_fsync_range+0x3b/0xa0
    do_fsync+0x3d/0x70
    SyS_fsync+0x10/0x20
    do_syscall_64+0x4d/0xb0
    entry_SYSCALL64_slow_path+0x25/0x25

Setting RT inode flags does not require special privileges so any
unprivileged user can cause this oops to occur.  To reproduce, confirm
kernel is compiled with CONFIG_XFS_RT=y and run:

  # mkfs.xfs -f /dev/pmem0
  # mount /dev/pmem0 /mnt/test
  # mkdir /mnt/test/foo
  # xfs_io -c 'chattr +t' /mnt/test/foo
  # xfs_io -f -c 'pwrite 0 5m' -c fsync /mnt/test/foo/bar

Or just run xfstests with MKFS_OPTIONS="-d rtinherit=1" and wait.

Kernels built with CONFIG_XFS_RT=n are not exposed to this bug.

Fixes: f538d4da8d52 ("[XFS] write barrier support")
Signed-off-by: Richard Wareing &lt;rwareing@fb.com&gt;
Signed-off-by: Dave Chinner &lt;david@fromorbit.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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commit b31ff3cdf540110da4572e3e29bd172087af65cc upstream.

If using a kernel with CONFIG_XFS_RT=y and we set the RHINHERIT flag on
a directory in a filesystem that does not have a realtime device and
create a new file in that directory, it gets marked as a real time file.
When data is written and a fsync is issued, the filesystem attempts to
flush a non-existent rt device during the fsync process.

This results in a crash dereferencing a null buftarg pointer in
xfs_blkdev_issue_flush():

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: xfs_blkdev_issue_flush+0xd/0x20
  .....
  Call Trace:
    xfs_file_fsync+0x188/0x1c0
    vfs_fsync_range+0x3b/0xa0
    do_fsync+0x3d/0x70
    SyS_fsync+0x10/0x20
    do_syscall_64+0x4d/0xb0
    entry_SYSCALL64_slow_path+0x25/0x25

Setting RT inode flags does not require special privileges so any
unprivileged user can cause this oops to occur.  To reproduce, confirm
kernel is compiled with CONFIG_XFS_RT=y and run:

  # mkfs.xfs -f /dev/pmem0
  # mount /dev/pmem0 /mnt/test
  # mkdir /mnt/test/foo
  # xfs_io -c 'chattr +t' /mnt/test/foo
  # xfs_io -f -c 'pwrite 0 5m' -c fsync /mnt/test/foo/bar

Or just run xfstests with MKFS_OPTIONS="-d rtinherit=1" and wait.

Kernels built with CONFIG_XFS_RT=n are not exposed to this bug.

Fixes: f538d4da8d52 ("[XFS] write barrier support")
Signed-off-by: Richard Wareing &lt;rwareing@fb.com&gt;
Signed-off-by: Dave Chinner &lt;david@fromorbit.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
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