<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/fs, branch v5.2.3</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>pstore: Fix double-free in pstore_mkfile() failure path</title>
<updated>2019-07-26T07:11:11+00:00</updated>
<author>
<name>Norbert Manthey</name>
<email>nmanthey@amazon.de</email>
</author>
<published>2019-07-05T13:06:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6f46c8c5d091ed4be38f46ae7931b06dbf301735'/>
<id>6f46c8c5d091ed4be38f46ae7931b06dbf301735</id>
<content type='text'>
commit 4c6d80e1144bdf48cae6b602ae30d41f3e5c76a9 upstream.

The pstore_mkfile() function is passed a pointer to a struct
pstore_record. On success it consumes this 'record' pointer and
references it from the created inode.

On failure, however, it may or may not free the record. There are even
two different code paths which return -ENOMEM -- one of which does and
the other doesn't free the record.

Make the behaviour deterministic by never consuming and freeing the
record when returning failure, allowing the caller to do the cleanup
consistently.

Signed-off-by: Norbert Manthey &lt;nmanthey@amazon.de&gt;
Link: https://lore.kernel.org/r/1562331960-26198-1-git-send-email-nmanthey@amazon.de
Fixes: 83f70f0769ddd ("pstore: Do not duplicate record metadata")
Fixes: 1dfff7dd67d1a ("pstore: Pass record contents instead of copying")
Cc: stable@vger.kernel.org
[kees: also move "private" allocation location, rename inode cleanup label]
Signed-off-by: Kees Cook &lt;keescook@chromium.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 4c6d80e1144bdf48cae6b602ae30d41f3e5c76a9 upstream.

The pstore_mkfile() function is passed a pointer to a struct
pstore_record. On success it consumes this 'record' pointer and
references it from the created inode.

On failure, however, it may or may not free the record. There are even
two different code paths which return -ENOMEM -- one of which does and
the other doesn't free the record.

Make the behaviour deterministic by never consuming and freeing the
record when returning failure, allowing the caller to do the cleanup
consistently.

Signed-off-by: Norbert Manthey &lt;nmanthey@amazon.de&gt;
Link: https://lore.kernel.org/r/1562331960-26198-1-git-send-email-nmanthey@amazon.de
Fixes: 83f70f0769ddd ("pstore: Do not duplicate record metadata")
Fixes: 1dfff7dd67d1a ("pstore: Pass record contents instead of copying")
Cc: stable@vger.kernel.org
[kees: also move "private" allocation location, rename inode cleanup label]
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>dax: Fix missed wakeup with PMD faults</title>
<updated>2019-07-26T07:11:10+00:00</updated>
<author>
<name>Matthew Wilcox (Oracle)</name>
<email>willy@infradead.org</email>
</author>
<published>2019-07-04T03:21:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=111b055e43cbca1761eaea0812e35dea556cb8d5'/>
<id>111b055e43cbca1761eaea0812e35dea556cb8d5</id>
<content type='text'>
commit 23c84eb7837514e16d79ed6d849b13745e0ce688 upstream.

RocksDB can hang indefinitely when using a DAX file.  This is due to
a bug in the XArray conversion when handling a PMD fault and finding a
PTE entry.  We use the wrong index in the hash and end up waiting on
the wrong waitqueue.

There's actually no need to wait; if we find a PTE entry while looking
for a PMD entry, we can return immediately as we know we should fall
back to a PTE fault (which may not conflict with the lock held).

We reuse the XA_RETRY_ENTRY to signal a conflicting entry was found.
This value can never be found in an XArray while holding its lock, so
it does not create an ambiguity.

Cc: &lt;stable@vger.kernel.org&gt;
Link: http://lkml.kernel.org/r/CAPcyv4hwHpX-MkUEqxwdTj7wCCZCN4RV-L4jsnuwLGyL_UEG4A@mail.gmail.com
Fixes: b15cd800682f ("dax: Convert page fault handlers to XArray")
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Tested-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
Reported-by: Robert Barror &lt;robert.barror@intel.com&gt;
Reported-by: Seema Pandit &lt;seema.pandit@intel.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Dan Williams &lt;dan.j.williams@intel.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 23c84eb7837514e16d79ed6d849b13745e0ce688 upstream.

RocksDB can hang indefinitely when using a DAX file.  This is due to
a bug in the XArray conversion when handling a PMD fault and finding a
PTE entry.  We use the wrong index in the hash and end up waiting on
the wrong waitqueue.

There's actually no need to wait; if we find a PTE entry while looking
for a PMD entry, we can return immediately as we know we should fall
back to a PTE fault (which may not conflict with the lock held).

We reuse the XA_RETRY_ENTRY to signal a conflicting entry was found.
This value can never be found in an XArray while holding its lock, so
it does not create an ambiguity.

Cc: &lt;stable@vger.kernel.org&gt;
Link: http://lkml.kernel.org/r/CAPcyv4hwHpX-MkUEqxwdTj7wCCZCN4RV-L4jsnuwLGyL_UEG4A@mail.gmail.com
Fixes: b15cd800682f ("dax: Convert page fault handlers to XArray")
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Tested-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
Reported-by: Robert Barror &lt;robert.barror@intel.com&gt;
Reported-by: Seema Pandit &lt;seema.pandit@intel.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>eCryptfs: fix a couple type promotion bugs</title>
<updated>2019-07-26T07:11:09+00:00</updated>
<author>
<name>Dan Carpenter</name>
<email>dan.carpenter@oracle.com</email>
</author>
<published>2018-07-04T09:35:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=abbd63bf086d03897569a5a6f56f87e6af222b58'/>
<id>abbd63bf086d03897569a5a6f56f87e6af222b58</id>
<content type='text'>
commit 0bdf8a8245fdea6f075a5fede833a5fcf1b3466c upstream.

ECRYPTFS_SIZE_AND_MARKER_BYTES is type size_t, so if "rc" is negative
that gets type promoted to a high positive value and treated as success.

Fixes: 778aeb42a708 ("eCryptfs: Cleanup and optimize ecryptfs_lookup_interpose()")
Signed-off-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
[tyhicks: Use "if/else if" rather than "if/if"]
Cc: stable@vger.kernel.org
Signed-off-by: Tyler Hicks &lt;tyhicks@canonical.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 0bdf8a8245fdea6f075a5fede833a5fcf1b3466c upstream.

ECRYPTFS_SIZE_AND_MARKER_BYTES is type size_t, so if "rc" is negative
that gets type promoted to a high positive value and treated as success.

Fixes: 778aeb42a708 ("eCryptfs: Cleanup and optimize ecryptfs_lookup_interpose()")
Signed-off-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
[tyhicks: Use "if/else if" rather than "if/if"]
Cc: stable@vger.kernel.org
Signed-off-by: Tyler Hicks &lt;tyhicks@canonical.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>coda: pass the host file in vma-&gt;vm_file on mmap</title>
<updated>2019-07-26T07:11:07+00:00</updated>
<author>
<name>Jan Harkes</name>
<email>jaharkes@cs.cmu.edu</email>
</author>
<published>2019-07-16T23:28:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c8ab9aafa60a92e95e148cd3b5af91843492fcd1'/>
<id>c8ab9aafa60a92e95e148cd3b5af91843492fcd1</id>
<content type='text'>
commit 7fa0a1da3dadfd9216df7745a1331fdaa0940d1c upstream.

Patch series "Coda updates".

The following patch series is a collection of various fixes for Coda,
most of which were collected from linux-fsdevel or linux-kernel but
which have as yet not found their way upstream.

This patch (of 22):

Various file systems expect that vma-&gt;vm_file points at their own file
handle, several use file_inode(vma-&gt;vm_file) to get at their inode or
use vma-&gt;vm_file-&gt;private_data.  However the way Coda wrapped mmap on a
host file broke this assumption, vm_file was still pointing at the Coda
file and the host file systems would scribble over Coda's inode and
private file data.

This patch fixes the incorrect expectation and wraps vm_ops-&gt;open and
vm_ops-&gt;close to allow Coda to track when the vm_area_struct is
destroyed so we still release the reference on the Coda file handle at
the right time.

Link: http://lkml.kernel.org/r/0e850c6e59c0b147dc2dcd51a3af004c948c3697.1558117389.git.jaharkes@cs.cmu.edu
Signed-off-by: Jan Harkes &lt;jaharkes@cs.cmu.edu&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Colin Ian King &lt;colin.king@canonical.com&gt;
Cc: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Fabian Frederick &lt;fabf@skynet.be&gt;
Cc: Mikko Rapeli &lt;mikko.rapeli@iki.fi&gt;
Cc: Sam Protsenko &lt;semen.protsenko@linaro.org&gt;
Cc: Yann Droneaud &lt;ydroneaud@opteya.com&gt;
Cc: Zhouyang Jia &lt;jiazhouyang09@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&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 7fa0a1da3dadfd9216df7745a1331fdaa0940d1c upstream.

Patch series "Coda updates".

The following patch series is a collection of various fixes for Coda,
most of which were collected from linux-fsdevel or linux-kernel but
which have as yet not found their way upstream.

This patch (of 22):

Various file systems expect that vma-&gt;vm_file points at their own file
handle, several use file_inode(vma-&gt;vm_file) to get at their inode or
use vma-&gt;vm_file-&gt;private_data.  However the way Coda wrapped mmap on a
host file broke this assumption, vm_file was still pointing at the Coda
file and the host file systems would scribble over Coda's inode and
private file data.

This patch fixes the incorrect expectation and wraps vm_ops-&gt;open and
vm_ops-&gt;close to allow Coda to track when the vm_area_struct is
destroyed so we still release the reference on the Coda file handle at
the right time.

Link: http://lkml.kernel.org/r/0e850c6e59c0b147dc2dcd51a3af004c948c3697.1558117389.git.jaharkes@cs.cmu.edu
Signed-off-by: Jan Harkes &lt;jaharkes@cs.cmu.edu&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Colin Ian King &lt;colin.king@canonical.com&gt;
Cc: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Fabian Frederick &lt;fabf@skynet.be&gt;
Cc: Mikko Rapeli &lt;mikko.rapeli@iki.fi&gt;
Cc: Sam Protsenko &lt;semen.protsenko@linaro.org&gt;
Cc: Yann Droneaud &lt;ydroneaud@opteya.com&gt;
Cc: Zhouyang Jia &lt;jiazhouyang09@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&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>Btrfs: add missing inode version, ctime and mtime updates when punching hole</title>
<updated>2019-07-26T07:11:05+00:00</updated>
<author>
<name>Filipe Manana</name>
<email>fdmanana@suse.com</email>
</author>
<published>2019-06-19T12:05:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b6a0d03dd4ea4733aaaf0a7e5c4beaaf8ac10306'/>
<id>b6a0d03dd4ea4733aaaf0a7e5c4beaaf8ac10306</id>
<content type='text'>
commit 179006688a7e888cbff39577189f2e034786d06a upstream.

If the range for which we are punching a hole covers only part of a page,
we end up updating the inode item but we skip the update of the inode's
iversion, mtime and ctime. Fix that by ensuring we update those properties
of the inode.

A patch for fstests test case generic/059 that tests this as been sent
along with this fix.

Fixes: 2aaa66558172b0 ("Btrfs: add hole punching")
Fixes: e8c1c76e804b18 ("Btrfs: add missing inode update when punching hole")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana &lt;fdmanana@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 179006688a7e888cbff39577189f2e034786d06a upstream.

If the range for which we are punching a hole covers only part of a page,
we end up updating the inode item but we skip the update of the inode's
iversion, mtime and ctime. Fix that by ensuring we update those properties
of the inode.

A patch for fstests test case generic/059 that tests this as been sent
along with this fix.

Fixes: 2aaa66558172b0 ("Btrfs: add hole punching")
Fixes: e8c1c76e804b18 ("Btrfs: add missing inode update when punching hole")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana &lt;fdmanana@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>Btrfs: fix fsync not persisting dentry deletions due to inode evictions</title>
<updated>2019-07-26T07:11:05+00:00</updated>
<author>
<name>Filipe Manana</name>
<email>fdmanana@suse.com</email>
</author>
<published>2019-06-19T12:05:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=24ae804edf6d76bb7c6c7d64c5a331c8c482f7c4'/>
<id>24ae804edf6d76bb7c6c7d64c5a331c8c482f7c4</id>
<content type='text'>
commit 803f0f64d17769071d7287d9e3e3b79a3e1ae937 upstream.

In order to avoid searches on a log tree when unlinking an inode, we check
if the inode being unlinked was logged in the current transaction, as well
as the inode of its parent directory. When any of the inodes are logged,
we proceed to delete directory items and inode reference items from the
log, to ensure that if a subsequent fsync of only the inode being unlinked
or only of the parent directory when the other is not fsync'ed as well,
does not result in the entry still existing after a power failure.

That check however is not reliable when one of the inodes involved (the
one being unlinked or its parent directory's inode) is evicted, since the
logged_trans field is transient, that is, it is not stored on disk, so it
is lost when the inode is evicted and loaded into memory again (which is
set to zero on load). As a consequence the checks currently being done by
btrfs_del_dir_entries_in_log() and btrfs_del_inode_ref_in_log() always
return true if the inode was evicted before, regardless of the inode
having been logged or not before (and in the current transaction), this
results in the dentry being unlinked still existing after a log replay
if after the unlink operation only one of the inodes involved is fsync'ed.

Example:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ mkdir /mnt/dir
  $ touch /mnt/dir/foo
  $ xfs_io -c fsync /mnt/dir/foo

  # Keep an open file descriptor on our directory while we evict inodes.
  # We just want to evict the file's inode, the directory's inode must not
  # be evicted.
  $ ( cd /mnt/dir; while true; do :; done ) &amp;
  $ pid=$!

  # Wait a bit to give time to background process to chdir to our test
  # directory.
  $ sleep 0.5

  # Trigger eviction of the file's inode.
  $ echo 2 &gt; /proc/sys/vm/drop_caches

  # Unlink our file and fsync the parent directory. After a power failure
  # we don't expect to see the file anymore, since we fsync'ed the parent
  # directory.
  $ rm -f $SCRATCH_MNT/dir/foo
  $ xfs_io -c fsync /mnt/dir

  &lt;power failure&gt;

  $ mount /dev/sdb /mnt
  $ ls /mnt/dir
  foo
  $
   --&gt; file still there, unlink not persisted despite explicit fsync on dir

Fix this by checking if the inode has the full_sync bit set in its runtime
flags as well, since that bit is set everytime an inode is loaded from
disk, or for other less common cases such as after a shrinking truncate
or failure to allocate extent maps for holes, and gets cleared after the
first fsync. Also consider the inode as possibly logged only if it was
last modified in the current transaction (besides having the full_fsync
flag set).

Fixes: 3a5f1d458ad161 ("Btrfs: Optimize btree walking while logging inodes")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana &lt;fdmanana@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 803f0f64d17769071d7287d9e3e3b79a3e1ae937 upstream.

In order to avoid searches on a log tree when unlinking an inode, we check
if the inode being unlinked was logged in the current transaction, as well
as the inode of its parent directory. When any of the inodes are logged,
we proceed to delete directory items and inode reference items from the
log, to ensure that if a subsequent fsync of only the inode being unlinked
or only of the parent directory when the other is not fsync'ed as well,
does not result in the entry still existing after a power failure.

That check however is not reliable when one of the inodes involved (the
one being unlinked or its parent directory's inode) is evicted, since the
logged_trans field is transient, that is, it is not stored on disk, so it
is lost when the inode is evicted and loaded into memory again (which is
set to zero on load). As a consequence the checks currently being done by
btrfs_del_dir_entries_in_log() and btrfs_del_inode_ref_in_log() always
return true if the inode was evicted before, regardless of the inode
having been logged or not before (and in the current transaction), this
results in the dentry being unlinked still existing after a log replay
if after the unlink operation only one of the inodes involved is fsync'ed.

Example:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ mkdir /mnt/dir
  $ touch /mnt/dir/foo
  $ xfs_io -c fsync /mnt/dir/foo

  # Keep an open file descriptor on our directory while we evict inodes.
  # We just want to evict the file's inode, the directory's inode must not
  # be evicted.
  $ ( cd /mnt/dir; while true; do :; done ) &amp;
  $ pid=$!

  # Wait a bit to give time to background process to chdir to our test
  # directory.
  $ sleep 0.5

  # Trigger eviction of the file's inode.
  $ echo 2 &gt; /proc/sys/vm/drop_caches

  # Unlink our file and fsync the parent directory. After a power failure
  # we don't expect to see the file anymore, since we fsync'ed the parent
  # directory.
  $ rm -f $SCRATCH_MNT/dir/foo
  $ xfs_io -c fsync /mnt/dir

  &lt;power failure&gt;

  $ mount /dev/sdb /mnt
  $ ls /mnt/dir
  foo
  $
   --&gt; file still there, unlink not persisted despite explicit fsync on dir

Fix this by checking if the inode has the full_sync bit set in its runtime
flags as well, since that bit is set everytime an inode is loaded from
disk, or for other less common cases such as after a shrinking truncate
or failure to allocate extent maps for holes, and gets cleared after the
first fsync. Also consider the inode as possibly logged only if it was
last modified in the current transaction (besides having the full_fsync
flag set).

Fixes: 3a5f1d458ad161 ("Btrfs: Optimize btree walking while logging inodes")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana &lt;fdmanana@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>Btrfs: fix data loss after inode eviction, renaming it, and fsync it</title>
<updated>2019-07-26T07:11:05+00:00</updated>
<author>
<name>Filipe Manana</name>
<email>fdmanana@suse.com</email>
</author>
<published>2019-06-07T10:25:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=12e58c1b445e48f8b21740407242bbe422be42ee'/>
<id>12e58c1b445e48f8b21740407242bbe422be42ee</id>
<content type='text'>
commit d1d832a0b51dd9570429bb4b81b2a6c1759e681a upstream.

When we log an inode, regardless of logging it completely or only that it
exists, we always update it as logged (logged_trans and last_log_commit
fields of the inode are updated). This is generally fine and avoids future
attempts to log it from having to do repeated work that brings no value.

However, if we write data to a file, then evict its inode after all the
dealloc was flushed (and ordered extents completed), rename the file and
fsync it, we end up not logging the new extents, since the rename may
result in logging that the inode exists in case the parent directory was
logged before. The following reproducer shows and explains how this can
happen:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ mkdir /mnt/dir
  $ touch /mnt/dir/foo
  $ touch /mnt/dir/bar

  # Do a direct IO write instead of a buffered write because with a
  # buffered write we would need to make sure dealloc gets flushed and
  # complete before we do the inode eviction later, and we can not do that
  # from user space with call to things such as sync(2) since that results
  # in a transaction commit as well.
  $ xfs_io -d -c "pwrite -S 0xd3 0 4K" /mnt/dir/bar

  # Keep the directory dir in use while we evict inodes. We want our file
  # bar's inode to be evicted but we don't want our directory's inode to
  # be evicted (if it were evicted too, we would not be able to reproduce
  # the issue since the first fsync below, of file foo, would result in a
  # transaction commit.
  $ ( cd /mnt/dir; while true; do :; done ) &amp;
  $ pid=$!

  # Wait a bit to give time for the background process to chdir.
  $ sleep 0.1

  # Evict all inodes, except the inode for the directory dir because it is
  # currently in use by our background process.
  $ echo 2 &gt; /proc/sys/vm/drop_caches

  # fsync file foo, which ends up persisting information about the parent
  # directory because it is a new inode.
  $ xfs_io -c fsync /mnt/dir/foo

  # Rename bar, this results in logging that this inode exists (inode item,
  # names, xattrs) because the parent directory is in the log.
  $ mv /mnt/dir/bar /mnt/dir/baz

  # Now fsync baz, which ends up doing absolutely nothing because of the
  # rename operation which logged that the inode exists only.
  $ xfs_io -c fsync /mnt/dir/baz

  &lt;power failure&gt;

  $ mount /dev/sdb /mnt
  $ od -t x1 -A d /mnt/dir/baz
  0000000

    --&gt; Empty file, data we wrote is missing.

Fix this by not updating last_sub_trans of an inode when we are logging
only that it exists and the inode was not yet logged since it was loaded
from disk (full_sync bit set), this is enough to make btrfs_inode_in_log()
return false for this scenario and make us log the inode. The logged_trans
of the inode is still always setsince that alone is used to track if names
need to be deleted as part of unlink operations.

Fixes: 257c62e1bce03e ("Btrfs: avoid tree log commit when there are no changes")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana &lt;fdmanana@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 d1d832a0b51dd9570429bb4b81b2a6c1759e681a upstream.

When we log an inode, regardless of logging it completely or only that it
exists, we always update it as logged (logged_trans and last_log_commit
fields of the inode are updated). This is generally fine and avoids future
attempts to log it from having to do repeated work that brings no value.

However, if we write data to a file, then evict its inode after all the
dealloc was flushed (and ordered extents completed), rename the file and
fsync it, we end up not logging the new extents, since the rename may
result in logging that the inode exists in case the parent directory was
logged before. The following reproducer shows and explains how this can
happen:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ mkdir /mnt/dir
  $ touch /mnt/dir/foo
  $ touch /mnt/dir/bar

  # Do a direct IO write instead of a buffered write because with a
  # buffered write we would need to make sure dealloc gets flushed and
  # complete before we do the inode eviction later, and we can not do that
  # from user space with call to things such as sync(2) since that results
  # in a transaction commit as well.
  $ xfs_io -d -c "pwrite -S 0xd3 0 4K" /mnt/dir/bar

  # Keep the directory dir in use while we evict inodes. We want our file
  # bar's inode to be evicted but we don't want our directory's inode to
  # be evicted (if it were evicted too, we would not be able to reproduce
  # the issue since the first fsync below, of file foo, would result in a
  # transaction commit.
  $ ( cd /mnt/dir; while true; do :; done ) &amp;
  $ pid=$!

  # Wait a bit to give time for the background process to chdir.
  $ sleep 0.1

  # Evict all inodes, except the inode for the directory dir because it is
  # currently in use by our background process.
  $ echo 2 &gt; /proc/sys/vm/drop_caches

  # fsync file foo, which ends up persisting information about the parent
  # directory because it is a new inode.
  $ xfs_io -c fsync /mnt/dir/foo

  # Rename bar, this results in logging that this inode exists (inode item,
  # names, xattrs) because the parent directory is in the log.
  $ mv /mnt/dir/bar /mnt/dir/baz

  # Now fsync baz, which ends up doing absolutely nothing because of the
  # rename operation which logged that the inode exists only.
  $ xfs_io -c fsync /mnt/dir/baz

  &lt;power failure&gt;

  $ mount /dev/sdb /mnt
  $ od -t x1 -A d /mnt/dir/baz
  0000000

    --&gt; Empty file, data we wrote is missing.

Fix this by not updating last_sub_trans of an inode when we are logging
only that it exists and the inode was not yet logged since it was loaded
from disk (full_sync bit set), this is enough to make btrfs_inode_in_log()
return false for this scenario and make us log the inode. The logged_trans
of the inode is still always setsince that alone is used to track if names
need to be deleted as part of unlink operations.

Fixes: 257c62e1bce03e ("Btrfs: avoid tree log commit when there are no changes")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana &lt;fdmanana@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>btrfs: correctly validate compression type</title>
<updated>2019-07-26T07:11:05+00:00</updated>
<author>
<name>Johannes Thumshirn</name>
<email>jthumshirn@suse.de</email>
</author>
<published>2019-06-06T10:07:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ced88769e67d95e5e7748135ec5ff19df721921d'/>
<id>ced88769e67d95e5e7748135ec5ff19df721921d</id>
<content type='text'>
commit aa53e3bfac7205fb3a8815ac1c937fd6ed01b41e upstream.

Nikolay reported the following KASAN splat when running btrfs/048:

[ 1843.470920] ==================================================================
[ 1843.471971] BUG: KASAN: slab-out-of-bounds in strncmp+0x66/0xb0
[ 1843.472775] Read of size 1 at addr ffff888111e369e2 by task btrfs/3979

[ 1843.473904] CPU: 3 PID: 3979 Comm: btrfs Not tainted 5.2.0-rc3-default #536
[ 1843.475009] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 1843.476322] Call Trace:
[ 1843.476674]  dump_stack+0x7c/0xbb
[ 1843.477132]  ? strncmp+0x66/0xb0
[ 1843.477587]  print_address_description+0x114/0x320
[ 1843.478256]  ? strncmp+0x66/0xb0
[ 1843.478740]  ? strncmp+0x66/0xb0
[ 1843.479185]  __kasan_report+0x14e/0x192
[ 1843.479759]  ? strncmp+0x66/0xb0
[ 1843.480209]  kasan_report+0xe/0x20
[ 1843.480679]  strncmp+0x66/0xb0
[ 1843.481105]  prop_compression_validate+0x24/0x70
[ 1843.481798]  btrfs_xattr_handler_set_prop+0x65/0x160
[ 1843.482509]  __vfs_setxattr+0x71/0x90
[ 1843.483012]  __vfs_setxattr_noperm+0x84/0x130
[ 1843.483606]  vfs_setxattr+0xac/0xb0
[ 1843.484085]  setxattr+0x18c/0x230
[ 1843.484546]  ? vfs_setxattr+0xb0/0xb0
[ 1843.485048]  ? __mod_node_page_state+0x1f/0xa0
[ 1843.485672]  ? _raw_spin_unlock+0x24/0x40
[ 1843.486233]  ? __handle_mm_fault+0x988/0x1290
[ 1843.486823]  ? lock_acquire+0xb4/0x1e0
[ 1843.487330]  ? lock_acquire+0xb4/0x1e0
[ 1843.487842]  ? mnt_want_write_file+0x3c/0x80
[ 1843.488442]  ? debug_lockdep_rcu_enabled+0x22/0x40
[ 1843.489089]  ? rcu_sync_lockdep_assert+0xe/0x70
[ 1843.489707]  ? __sb_start_write+0x158/0x200
[ 1843.490278]  ? mnt_want_write_file+0x3c/0x80
[ 1843.490855]  ? __mnt_want_write+0x98/0xe0
[ 1843.491397]  __x64_sys_fsetxattr+0xba/0xe0
[ 1843.492201]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 1843.493201]  do_syscall_64+0x6c/0x230
[ 1843.493988]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 1843.495041] RIP: 0033:0x7fa7a8a7707a
[ 1843.495819] Code: 48 8b 0d 21 de 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 be 00 00 00 0f 05 &lt;48&gt; 3d 01 f0 ff ff 73 01 c3 48 8b 0d ee dd 2b 00 f7 d8 64 89 01 48
[ 1843.499203] RSP: 002b:00007ffcb73bca38 EFLAGS: 00000202 ORIG_RAX: 00000000000000be
[ 1843.500210] RAX: ffffffffffffffda RBX: 00007ffcb73bda9d RCX: 00007fa7a8a7707a
[ 1843.501170] RDX: 00007ffcb73bda9d RSI: 00000000006dc050 RDI: 0000000000000003
[ 1843.502152] RBP: 00000000006dc050 R08: 0000000000000000 R09: 0000000000000000
[ 1843.503109] R10: 0000000000000002 R11: 0000000000000202 R12: 00007ffcb73bda91
[ 1843.504055] R13: 0000000000000003 R14: 00007ffcb73bda82 R15: ffffffffffffffff

[ 1843.505268] Allocated by task 3979:
[ 1843.505771]  save_stack+0x19/0x80
[ 1843.506211]  __kasan_kmalloc.constprop.5+0xa0/0xd0
[ 1843.506836]  setxattr+0xeb/0x230
[ 1843.507264]  __x64_sys_fsetxattr+0xba/0xe0
[ 1843.507886]  do_syscall_64+0x6c/0x230
[ 1843.508429]  entry_SYSCALL_64_after_hwframe+0x49/0xbe

[ 1843.509558] Freed by task 0:
[ 1843.510188] (stack is not available)

[ 1843.511309] The buggy address belongs to the object at ffff888111e369e0
                which belongs to the cache kmalloc-8 of size 8
[ 1843.514095] The buggy address is located 2 bytes inside of
                8-byte region [ffff888111e369e0, ffff888111e369e8)
[ 1843.516524] The buggy address belongs to the page:
[ 1843.517561] page:ffff88813f478d80 refcount:1 mapcount:0 mapping:ffff88811940c300 index:0xffff888111e373b8 compound_mapcount: 0
[ 1843.519993] flags: 0x4404000010200(slab|head)
[ 1843.520951] raw: 0004404000010200 ffff88813f48b008 ffff888119403d50 ffff88811940c300
[ 1843.522616] raw: ffff888111e373b8 000000000016000f 00000001ffffffff 0000000000000000
[ 1843.524281] page dumped because: kasan: bad access detected

[ 1843.525936] Memory state around the buggy address:
[ 1843.526975]  ffff888111e36880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.528479]  ffff888111e36900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.530138] &gt;ffff888111e36980: fc fc fc fc fc fc fc fc fc fc fc fc 02 fc fc fc
[ 1843.531877]                                                        ^
[ 1843.533287]  ffff888111e36a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.534874]  ffff888111e36a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.536468] ==================================================================

This is caused by supplying a too short compression value ('lz') in the
test-case and comparing it to 'lzo' with strncmp() and a length of 3.
strncmp() read past the 'lz' when looking for the 'o' and thus caused an
out-of-bounds read.

Introduce a new check 'btrfs_compress_is_valid_type()' which not only
checks the user-supplied value against known compression types, but also
employs checks for too short values.

Reported-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Fixes: 272e5326c783 ("btrfs: prop: fix vanished compression property after failed set")
CC: stable@vger.kernel.org # 5.1+
Reviewed-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Signed-off-by: Johannes Thumshirn &lt;jthumshirn@suse.de&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 aa53e3bfac7205fb3a8815ac1c937fd6ed01b41e upstream.

Nikolay reported the following KASAN splat when running btrfs/048:

[ 1843.470920] ==================================================================
[ 1843.471971] BUG: KASAN: slab-out-of-bounds in strncmp+0x66/0xb0
[ 1843.472775] Read of size 1 at addr ffff888111e369e2 by task btrfs/3979

[ 1843.473904] CPU: 3 PID: 3979 Comm: btrfs Not tainted 5.2.0-rc3-default #536
[ 1843.475009] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 1843.476322] Call Trace:
[ 1843.476674]  dump_stack+0x7c/0xbb
[ 1843.477132]  ? strncmp+0x66/0xb0
[ 1843.477587]  print_address_description+0x114/0x320
[ 1843.478256]  ? strncmp+0x66/0xb0
[ 1843.478740]  ? strncmp+0x66/0xb0
[ 1843.479185]  __kasan_report+0x14e/0x192
[ 1843.479759]  ? strncmp+0x66/0xb0
[ 1843.480209]  kasan_report+0xe/0x20
[ 1843.480679]  strncmp+0x66/0xb0
[ 1843.481105]  prop_compression_validate+0x24/0x70
[ 1843.481798]  btrfs_xattr_handler_set_prop+0x65/0x160
[ 1843.482509]  __vfs_setxattr+0x71/0x90
[ 1843.483012]  __vfs_setxattr_noperm+0x84/0x130
[ 1843.483606]  vfs_setxattr+0xac/0xb0
[ 1843.484085]  setxattr+0x18c/0x230
[ 1843.484546]  ? vfs_setxattr+0xb0/0xb0
[ 1843.485048]  ? __mod_node_page_state+0x1f/0xa0
[ 1843.485672]  ? _raw_spin_unlock+0x24/0x40
[ 1843.486233]  ? __handle_mm_fault+0x988/0x1290
[ 1843.486823]  ? lock_acquire+0xb4/0x1e0
[ 1843.487330]  ? lock_acquire+0xb4/0x1e0
[ 1843.487842]  ? mnt_want_write_file+0x3c/0x80
[ 1843.488442]  ? debug_lockdep_rcu_enabled+0x22/0x40
[ 1843.489089]  ? rcu_sync_lockdep_assert+0xe/0x70
[ 1843.489707]  ? __sb_start_write+0x158/0x200
[ 1843.490278]  ? mnt_want_write_file+0x3c/0x80
[ 1843.490855]  ? __mnt_want_write+0x98/0xe0
[ 1843.491397]  __x64_sys_fsetxattr+0xba/0xe0
[ 1843.492201]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 1843.493201]  do_syscall_64+0x6c/0x230
[ 1843.493988]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 1843.495041] RIP: 0033:0x7fa7a8a7707a
[ 1843.495819] Code: 48 8b 0d 21 de 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 be 00 00 00 0f 05 &lt;48&gt; 3d 01 f0 ff ff 73 01 c3 48 8b 0d ee dd 2b 00 f7 d8 64 89 01 48
[ 1843.499203] RSP: 002b:00007ffcb73bca38 EFLAGS: 00000202 ORIG_RAX: 00000000000000be
[ 1843.500210] RAX: ffffffffffffffda RBX: 00007ffcb73bda9d RCX: 00007fa7a8a7707a
[ 1843.501170] RDX: 00007ffcb73bda9d RSI: 00000000006dc050 RDI: 0000000000000003
[ 1843.502152] RBP: 00000000006dc050 R08: 0000000000000000 R09: 0000000000000000
[ 1843.503109] R10: 0000000000000002 R11: 0000000000000202 R12: 00007ffcb73bda91
[ 1843.504055] R13: 0000000000000003 R14: 00007ffcb73bda82 R15: ffffffffffffffff

[ 1843.505268] Allocated by task 3979:
[ 1843.505771]  save_stack+0x19/0x80
[ 1843.506211]  __kasan_kmalloc.constprop.5+0xa0/0xd0
[ 1843.506836]  setxattr+0xeb/0x230
[ 1843.507264]  __x64_sys_fsetxattr+0xba/0xe0
[ 1843.507886]  do_syscall_64+0x6c/0x230
[ 1843.508429]  entry_SYSCALL_64_after_hwframe+0x49/0xbe

[ 1843.509558] Freed by task 0:
[ 1843.510188] (stack is not available)

[ 1843.511309] The buggy address belongs to the object at ffff888111e369e0
                which belongs to the cache kmalloc-8 of size 8
[ 1843.514095] The buggy address is located 2 bytes inside of
                8-byte region [ffff888111e369e0, ffff888111e369e8)
[ 1843.516524] The buggy address belongs to the page:
[ 1843.517561] page:ffff88813f478d80 refcount:1 mapcount:0 mapping:ffff88811940c300 index:0xffff888111e373b8 compound_mapcount: 0
[ 1843.519993] flags: 0x4404000010200(slab|head)
[ 1843.520951] raw: 0004404000010200 ffff88813f48b008 ffff888119403d50 ffff88811940c300
[ 1843.522616] raw: ffff888111e373b8 000000000016000f 00000001ffffffff 0000000000000000
[ 1843.524281] page dumped because: kasan: bad access detected

[ 1843.525936] Memory state around the buggy address:
[ 1843.526975]  ffff888111e36880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.528479]  ffff888111e36900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.530138] &gt;ffff888111e36980: fc fc fc fc fc fc fc fc fc fc fc fc 02 fc fc fc
[ 1843.531877]                                                        ^
[ 1843.533287]  ffff888111e36a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.534874]  ffff888111e36a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 1843.536468] ==================================================================

This is caused by supplying a too short compression value ('lz') in the
test-case and comparing it to 'lzo' with strncmp() and a length of 3.
strncmp() read past the 'lz' when looking for the 'o' and thus caused an
out-of-bounds read.

Introduce a new check 'btrfs_compress_is_valid_type()' which not only
checks the user-supplied value against known compression types, but also
employs checks for too short values.

Reported-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Fixes: 272e5326c783 ("btrfs: prop: fix vanished compression property after failed set")
CC: stable@vger.kernel.org # 5.1+
Reviewed-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Signed-off-by: Johannes Thumshirn &lt;jthumshirn@suse.de&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>fs/proc/proc_sysctl.c: fix the default values of i_uid/i_gid on /proc/sys inodes.</title>
<updated>2019-07-26T07:11:01+00:00</updated>
<author>
<name>Radoslaw Burny</name>
<email>rburny@google.com</email>
</author>
<published>2019-07-16T23:26:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=14cc90952cef94bfa89a6b4a2f55fd9a70f50a16'/>
<id>14cc90952cef94bfa89a6b4a2f55fd9a70f50a16</id>
<content type='text'>
commit 5ec27ec735ba0477d48c80561cc5e856f0c5dfaf upstream.

Normally, the inode's i_uid/i_gid are translated relative to s_user_ns,
but this is not a correct behavior for proc.  Since sysctl permission
check in test_perm is done against GLOBAL_ROOT_[UG]ID, it makes more
sense to use these values in u_[ug]id of proc inodes.  In other words:
although uid/gid in the inode is not read during test_perm, the inode
logically belongs to the root of the namespace.  I have confirmed this
with Eric Biederman at LPC and in this thread:
  https://lore.kernel.org/lkml/87k1kzjdff.fsf@xmission.com

Consequences
============

Since the i_[ug]id values of proc nodes are not used for permissions
checks, this change usually makes no functional difference.  However, it
causes an issue in a setup where:

 * a namespace container is created without root user in container -
   hence the i_[ug]id of proc nodes are set to INVALID_[UG]ID

 * container creator tries to configure it by writing /proc/sys files,
   e.g. writing /proc/sys/kernel/shmmax to configure shared memory limit

Kernel does not allow to open an inode for writing if its i_[ug]id are
invalid, making it impossible to write shmmax and thus - configure the
container.

Using a container with no root mapping is apparently rare, but we do use
this configuration at Google.  Also, we use a generic tool to configure
the container limits, and the inability to write any of them causes a
failure.

History
=======

The invalid uids/gids in inodes first appeared due to 81754357770e (fs:
Update i_[ug]id_(read|write) to translate relative to s_user_ns).
However, AFAIK, this did not immediately cause any issues.  The
inability to write to these "invalid" inodes was only caused by a later
commit 0bd23d09b874 (vfs: Don't modify inodes with a uid or gid unknown
to the vfs).

Tested: Used a repro program that creates a user namespace without any
mapping and stat'ed /proc/$PID/root/proc/sys/kernel/shmmax from outside.
Before the change, it shows the overflow uid, with the change it's 0.
The overflow uid indicates that the uid in the inode is not correct and
thus it is not possible to open the file for writing.

Link: http://lkml.kernel.org/r/20190708115130.250149-1-rburny@google.com
Fixes: 0bd23d09b874 ("vfs: Don't modify inodes with a uid or gid unknown to the vfs")
Signed-off-by: Radoslaw Burny &lt;rburny@google.com&gt;
Acked-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: "Eric W . Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Seth Forshee &lt;seth.forshee@canonical.com&gt;
Cc: John Sperbeck &lt;jsperbeck@google.com&gt;
Cc: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;	[4.8+]
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&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 5ec27ec735ba0477d48c80561cc5e856f0c5dfaf upstream.

Normally, the inode's i_uid/i_gid are translated relative to s_user_ns,
but this is not a correct behavior for proc.  Since sysctl permission
check in test_perm is done against GLOBAL_ROOT_[UG]ID, it makes more
sense to use these values in u_[ug]id of proc inodes.  In other words:
although uid/gid in the inode is not read during test_perm, the inode
logically belongs to the root of the namespace.  I have confirmed this
with Eric Biederman at LPC and in this thread:
  https://lore.kernel.org/lkml/87k1kzjdff.fsf@xmission.com

Consequences
============

Since the i_[ug]id values of proc nodes are not used for permissions
checks, this change usually makes no functional difference.  However, it
causes an issue in a setup where:

 * a namespace container is created without root user in container -
   hence the i_[ug]id of proc nodes are set to INVALID_[UG]ID

 * container creator tries to configure it by writing /proc/sys files,
   e.g. writing /proc/sys/kernel/shmmax to configure shared memory limit

Kernel does not allow to open an inode for writing if its i_[ug]id are
invalid, making it impossible to write shmmax and thus - configure the
container.

Using a container with no root mapping is apparently rare, but we do use
this configuration at Google.  Also, we use a generic tool to configure
the container limits, and the inability to write any of them causes a
failure.

History
=======

The invalid uids/gids in inodes first appeared due to 81754357770e (fs:
Update i_[ug]id_(read|write) to translate relative to s_user_ns).
However, AFAIK, this did not immediately cause any issues.  The
inability to write to these "invalid" inodes was only caused by a later
commit 0bd23d09b874 (vfs: Don't modify inodes with a uid or gid unknown
to the vfs).

Tested: Used a repro program that creates a user namespace without any
mapping and stat'ed /proc/$PID/root/proc/sys/kernel/shmmax from outside.
Before the change, it shows the overflow uid, with the change it's 0.
The overflow uid indicates that the uid in the inode is not correct and
thus it is not possible to open the file for writing.

Link: http://lkml.kernel.org/r/20190708115130.250149-1-rburny@google.com
Fixes: 0bd23d09b874 ("vfs: Don't modify inodes with a uid or gid unknown to the vfs")
Signed-off-by: Radoslaw Burny &lt;rburny@google.com&gt;
Acked-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: "Eric W . Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Seth Forshee &lt;seth.forshee@canonical.com&gt;
Cc: John Sperbeck &lt;jsperbeck@google.com&gt;
Cc: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;	[4.8+]
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&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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</entry>
<entry>
<title>ceph: use ceph_evict_inode to cleanup inode's resource</title>
<updated>2019-07-26T07:10:58+00:00</updated>
<author>
<name>Yan, Zheng</name>
<email>zyan@redhat.com</email>
</author>
<published>2019-06-02T01:45:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=31d15efb4c4d87c5c80f0a89648977d6520be6d8'/>
<id>31d15efb4c4d87c5c80f0a89648977d6520be6d8</id>
<content type='text'>
commit 87bc5b895d94a0f40fe170d4cf5771c8e8f85d15 upstream.

remove_session_caps() relies on __wait_on_freeing_inode(), to wait for
freeing inode to remove its caps. But VFS wakes freeing inode waiters
before calling destroy_inode().

Cc: stable@vger.kernel.org
Link: https://tracker.ceph.com/issues/40102
Signed-off-by: "Yan, Zheng" &lt;zyan@redhat.com&gt;
Reviewed-by: Jeff Layton &lt;jlayton@redhat.com&gt;
Signed-off-by: Ilya Dryomov &lt;idryomov@gmail.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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<pre>
commit 87bc5b895d94a0f40fe170d4cf5771c8e8f85d15 upstream.

remove_session_caps() relies on __wait_on_freeing_inode(), to wait for
freeing inode to remove its caps. But VFS wakes freeing inode waiters
before calling destroy_inode().

Cc: stable@vger.kernel.org
Link: https://tracker.ceph.com/issues/40102
Signed-off-by: "Yan, Zheng" &lt;zyan@redhat.com&gt;
Reviewed-by: Jeff Layton &lt;jlayton@redhat.com&gt;
Signed-off-by: Ilya Dryomov &lt;idryomov@gmail.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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