<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/fs, branch v4.4.121</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>btrfs: preserve i_mode if __btrfs_set_acl() fails</title>
<updated>2018-03-11T15:19:47+00:00</updated>
<author>
<name>Ernesto A. Fernández</name>
<email>ernesto.mnd.fernandez@gmail.com</email>
</author>
<published>2017-08-02T06:18:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0fc85640c6a8d84bdab008f285346061a8fc393d'/>
<id>0fc85640c6a8d84bdab008f285346061a8fc393d</id>
<content type='text'>
commit d7d824966530acfe32b94d1ed672e6fe1638cd68 upstream.

When changing a file's acl mask, btrfs_set_acl() will first set the
group bits of i_mode to the value of the mask, and only then set the
actual extended attribute representing the new acl.

If the second part fails (due to lack of space, for example) and the
file had no acl attribute to begin with, the system will from now on
assume that the mask permission bits are actual group permission bits,
potentially granting access to the wrong users.

Prevent this by restoring the original mode bits if __btrfs_set_acl
fails.

Signed-off-by: Ernesto A. Fernández &lt;ernesto.mnd.fernandez@gmail.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Nikolay Borisov &lt;nborisov@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 d7d824966530acfe32b94d1ed672e6fe1638cd68 upstream.

When changing a file's acl mask, btrfs_set_acl() will first set the
group bits of i_mode to the value of the mask, and only then set the
actual extended attribute representing the new acl.

If the second part fails (due to lack of space, for example) and the
file had no acl attribute to begin with, the system will from now on
assume that the mask permission bits are actual group permission bits,
potentially granting access to the wrong users.

Prevent this by restoring the original mode bits if __btrfs_set_acl
fails.

Signed-off-by: Ernesto A. Fernández &lt;ernesto.mnd.fernandez@gmail.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;


</pre>
</div>
</content>
</entry>
<entry>
<title>btrfs: Don't clear SGID when inheriting ACLs</title>
<updated>2018-03-11T15:19:45+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2017-06-22T13:31:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=aa75b56eb5406294a7eb6f0d57059d1cff5fd846'/>
<id>aa75b56eb5406294a7eb6f0d57059d1cff5fd846</id>
<content type='text'>
commit b7f8a09f8097db776b8d160862540e4fc1f51296 upstream.

When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
set, DIR1 is expected to have SGID bit set (and owning group equal to
the owning group of 'DIR0'). However when 'DIR0' also has some default
ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
'DIR1' to get cleared if user is not member of the owning group.

Fix the problem by moving posix_acl_update_mode() out of
__btrfs_set_acl() into btrfs_set_acl(). That way the function will not be
called when inheriting ACLs which is what we want as it prevents SGID
bit clearing and the mode has been properly set by posix_acl_create()
anyway.

Fixes: 073931017b49d9458aa351605b43a7e34598caef
CC: stable@vger.kernel.org
CC: linux-btrfs@vger.kernel.org
CC: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Nikolay Borisov &lt;nborisov@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 b7f8a09f8097db776b8d160862540e4fc1f51296 upstream.

When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
set, DIR1 is expected to have SGID bit set (and owning group equal to
the owning group of 'DIR0'). However when 'DIR0' also has some default
ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
'DIR1' to get cleared if user is not member of the owning group.

Fix the problem by moving posix_acl_update_mode() out of
__btrfs_set_acl() into btrfs_set_acl(). That way the function will not be
called when inheriting ACLs which is what we want as it prevents SGID
bit clearing and the mode has been properly set by posix_acl_create()
anyway.

Fixes: 073931017b49d9458aa351605b43a7e34598caef
CC: stable@vger.kernel.org
CC: linux-btrfs@vger.kernel.org
CC: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xfs: quota: check result of register_shrinker()</title>
<updated>2018-03-03T09:19:44+00:00</updated>
<author>
<name>Aliaksei Karaliou</name>
<email>akaraliou.dev@gmail.com</email>
</author>
<published>2017-12-21T21:18:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6bfb63b4e796aadf5ac7a2988c68bda5fa265977'/>
<id>6bfb63b4e796aadf5ac7a2988c68bda5fa265977</id>
<content type='text'>
[ Upstream commit 3a3882ff26fbdbaf5f7e13f6a0bccfbf7121041d ]

xfs_qm_init_quotainfo() does not check result of register_shrinker()
which was tagged as __must_check recently, reported by sparse.

Signed-off-by: Aliaksei Karaliou &lt;akaraliou.dev@gmail.com&gt;
[darrick: move xfs_qm_destroy_quotainos nearer xfs_qm_init_quotainos]
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;

Signed-off-by: Sasha Levin &lt;alexander.levin@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>
[ Upstream commit 3a3882ff26fbdbaf5f7e13f6a0bccfbf7121041d ]

xfs_qm_init_quotainfo() does not check result of register_shrinker()
which was tagged as __must_check recently, reported by sparse.

Signed-off-by: Aliaksei Karaliou &lt;akaraliou.dev@gmail.com&gt;
[darrick: move xfs_qm_destroy_quotainos nearer xfs_qm_init_quotainos]
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;

Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xfs: quota: fix missed destroy of qi_tree_lock</title>
<updated>2018-03-03T09:19:44+00:00</updated>
<author>
<name>Aliaksei Karaliou</name>
<email>akaraliou.dev@gmail.com</email>
</author>
<published>2017-12-21T21:18:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a72e35738163e36905012537c6a44c87fa61475a'/>
<id>a72e35738163e36905012537c6a44c87fa61475a</id>
<content type='text'>
[ Upstream commit 2196881566225f3c3428d1a5f847a992944daa5b ]

xfs_qm_destroy_quotainfo() does not destroy quotainfo-&gt;qi_tree_lock
while destroys quotainfo-&gt;qi_quotaofflock.

Signed-off-by: Aliaksei Karaliou &lt;akaraliou.dev@gmail.com&gt;
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@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>
[ Upstream commit 2196881566225f3c3428d1a5f847a992944daa5b ]

xfs_qm_destroy_quotainfo() does not destroy quotainfo-&gt;qi_tree_lock
while destroys quotainfo-&gt;qi_quotaofflock.

Signed-off-by: Aliaksei Karaliou &lt;akaraliou.dev@gmail.com&gt;
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sget(): handle failures of register_shrinker()</title>
<updated>2018-03-03T09:19:41+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2017-12-18T20:05:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4cf1dead545b29f92722c8d1021db26beee31c83'/>
<id>4cf1dead545b29f92722c8d1021db26beee31c83</id>
<content type='text'>
[ Upstream commit 9ee332d99e4d5a97548943b81c54668450ce641b ]

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@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>
[ Upstream commit 9ee332d99e4d5a97548943b81c54668450ce641b ]

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: fix a bug caused by NULL extent tree</title>
<updated>2018-03-03T09:19:41+00:00</updated>
<author>
<name>Yunlei He</name>
<email>heyunlei@huawei.com</email>
</author>
<published>2017-05-19T07:06:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=023ca5b884d2759b56dc8d480942835881853513'/>
<id>023ca5b884d2759b56dc8d480942835881853513</id>
<content type='text'>
commit dad48e73127ba10279ea33e6dbc8d3905c4d31c0 upstream.

Thread A:					Thread B:

-f2fs_remount
    -sbi-&gt;mount_opt.opt = 0;
						&lt;--- -f2fs_iget
						         -do_read_inode
							     -f2fs_init_extent_tree
							         -F2FS_I(inode)-&gt;extent_tree is NULL
        -default_options &amp;&amp; parse_options
	    -remount return
						&lt;---  -f2fs_map_blocks
						          -f2fs_lookup_extent_tree
                                                              -f2fs_bug_on(sbi, !et);

The same problem with f2fs_new_inode.

Signed-off-by: Yunlei He &lt;heyunlei@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Signed-off-by: Nikolay Borisov &lt;nborisov@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 dad48e73127ba10279ea33e6dbc8d3905c4d31c0 upstream.

Thread A:					Thread B:

-f2fs_remount
    -sbi-&gt;mount_opt.opt = 0;
						&lt;--- -f2fs_iget
						         -do_read_inode
							     -f2fs_init_extent_tree
							         -F2FS_I(inode)-&gt;extent_tree is NULL
        -default_options &amp;&amp; parse_options
	    -remount return
						&lt;---  -f2fs_map_blocks
						          -f2fs_lookup_extent_tree
                                                              -f2fs_bug_on(sbi, !et);

The same problem with f2fs_new_inode.

Signed-off-by: Yunlei He &lt;heyunlei@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Signed-off-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>binfmt_elf: compat: avoid unused function warning</title>
<updated>2018-02-25T10:03:51+00:00</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2018-02-20T11:54:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b8b624d9885fea0d0bb7f51d9548004cd6882002'/>
<id>b8b624d9885fea0d0bb7f51d9548004cd6882002</id>
<content type='text'>
When CONFIG_ELF_CORE is disabled, we get a harmless warning in the compat
version of binfmt_elf:

fs/compat_binfmt_elf.c:58:13: error: 'cputime_to_compat_timeval' defined but not used [-Werror=unused-function]

This was addressed in mainline Linux as part of a larger rework with commit
cd19c364b313 ("fs/binfmt: Convert obsolete cputime type to nsecs").

For 4.9 and earlier, this just shuts up the warning by adding an #ifdef
around the function definition.

Signed-off-by: Arnd Bergmann &lt;arnd@arndb.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>
When CONFIG_ELF_CORE is disabled, we get a harmless warning in the compat
version of binfmt_elf:

fs/compat_binfmt_elf.c:58:13: error: 'cputime_to_compat_timeval' defined but not used [-Werror=unused-function]

This was addressed in mainline Linux as part of a larger rework with commit
cd19c364b313 ("fs/binfmt: Convert obsolete cputime type to nsecs").

For 4.9 and earlier, this just shuts up the warning by adding an #ifdef
around the function definition.

Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ncpfs: fix unused variable warning</title>
<updated>2018-02-25T10:03:50+00:00</updated>
<author>
<name>Miklos Szeredi</name>
<email>mszeredi@redhat.com</email>
</author>
<published>2016-09-27T09:03:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=633c324b829e13005b12470da1b2d5d447030e82'/>
<id>633c324b829e13005b12470da1b2d5d447030e82</id>
<content type='text'>
commit 9a232de4999666b2e8ea6775b2b0e3e4feb09b7a upstream.

Without CONFIG_NCPFS_NLS the following warning is seen:

fs/ncpfs/dir.c: In function 'ncp_hash_dentry':
fs/ncpfs/dir.c:136:23: warning: unused variable 'sb' [-Wunused-variable]
   struct super_block *sb = dentry-&gt;d_sb;

Signed-off-by: Miklos Szeredi &lt;mszeredi@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 9a232de4999666b2e8ea6775b2b0e3e4feb09b7a upstream.

Without CONFIG_NCPFS_NLS the following warning is seen:

fs/ncpfs/dir.c: In function 'ncp_hash_dentry':
fs/ncpfs/dir.c:136:23: warning: unused variable 'sb' [-Wunused-variable]
   struct super_block *sb = dentry-&gt;d_sb;

Signed-off-by: Miklos Szeredi &lt;mszeredi@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>reiserfs: avoid a -Wmaybe-uninitialized warning</title>
<updated>2018-02-25T10:03:43+00:00</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2017-03-23T15:06:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a8aeea21973fc72d8fc587862b79acdc61411ff8'/>
<id>a8aeea21973fc72d8fc587862b79acdc61411ff8</id>
<content type='text'>
commit ab4949640d6674b617b314ad3c2c00353304bab9 upstream.

The latest gcc-7.0.1 snapshot warns about an unintialized variable use:

In file included from fs/reiserfs/lbalance.c:8:0:
fs/reiserfs/lbalance.c: In function 'leaf_item_bottle.isra.3':
fs/reiserfs/reiserfs.h:1279:13: error: '*((void *)&amp;n_ih+8).v' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  v2-&gt;v = (v2-&gt;v &amp; cpu_to_le64(15ULL &lt;&lt; 60)) | cpu_to_le64(offset);
           ~~^~~
fs/reiserfs/reiserfs.h:1279:13: error: '*((void *)&amp;n_ih+8).v' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  v2-&gt;v = (v2-&gt;v &amp; cpu_to_le64(15ULL &lt;&lt; 60)) | cpu_to_le64(offset);

This happens because the offset/type pair that is stored in
ih.key.u.k_offset_v2 is actually uninitialized when we call
set_le_ih_k_offset() and set_le_ih_k_type(). After we have called both,
all data is correct, but the first of the two reads uninitialized data
for the type field and writes it back before it gets overwritten.

This works around the warning by initializing the k_offset_v2 through
the slightly larger memcpy().

[JK: Remove now unused define and make it obvious we initialize the key]

Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-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 ab4949640d6674b617b314ad3c2c00353304bab9 upstream.

The latest gcc-7.0.1 snapshot warns about an unintialized variable use:

In file included from fs/reiserfs/lbalance.c:8:0:
fs/reiserfs/lbalance.c: In function 'leaf_item_bottle.isra.3':
fs/reiserfs/reiserfs.h:1279:13: error: '*((void *)&amp;n_ih+8).v' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  v2-&gt;v = (v2-&gt;v &amp; cpu_to_le64(15ULL &lt;&lt; 60)) | cpu_to_le64(offset);
           ~~^~~
fs/reiserfs/reiserfs.h:1279:13: error: '*((void *)&amp;n_ih+8).v' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  v2-&gt;v = (v2-&gt;v &amp; cpu_to_le64(15ULL &lt;&lt; 60)) | cpu_to_le64(offset);

This happens because the offset/type pair that is stored in
ih.key.u.k_offset_v2 is actually uninitialized when we call
set_le_ih_k_offset() and set_le_ih_k_type(). After we have called both,
all data is correct, but the first of the two reads uninitialized data
for the type field and writes it back before it gets overwritten.

This works around the warning by initializing the k_offset_v2 through
the slightly larger memcpy().

[JK: Remove now unused define and make it obvious we initialize the key]

Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-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>btrfs: Fix possible off-by-one in btrfs_search_path_in_tree</title>
<updated>2018-02-25T10:03:40+00:00</updated>
<author>
<name>Nikolay Borisov</name>
<email>nborisov@suse.com</email>
</author>
<published>2017-12-01T09:19:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6fdf5856c6a513a6b2ea37c0fed2b1450e611be6'/>
<id>6fdf5856c6a513a6b2ea37c0fed2b1450e611be6</id>
<content type='text'>
[ Upstream commit c8bcbfbd239ed60a6562964b58034ac8a25f4c31 ]

The name char array passed to btrfs_search_path_in_tree is of size
BTRFS_INO_LOOKUP_PATH_MAX (4080). So the actual accessible char indexes
are in the range of [0, 4079]. Currently the code uses the define but this
represents an off-by-one.

Implications:

Size of btrfs_ioctl_ino_lookup_args is 4096, so the new byte will be
written to extra space, not some padding that could be provided by the
allocator.

btrfs-progs store the arguments on stack, but kernel does own copy of
the ioctl buffer and the off-by-one overwrite does not affect userspace,
but the ending 0 might be lost.

Kernel ioctl buffer is allocated dynamically so we're overwriting
somebody else's memory, and the ioctl is privileged if args.objectid is
not 256. Which is in most cases, but resolving a subvolume stored in
another directory will trigger that path.

Before this patch the buffer was one byte larger, but then the -1 was
not added.

Fixes: ac8e9819d71f907 ("Btrfs: add search and inode lookup ioctls")
Signed-off-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
[ added implications ]
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;

Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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[ Upstream commit c8bcbfbd239ed60a6562964b58034ac8a25f4c31 ]

The name char array passed to btrfs_search_path_in_tree is of size
BTRFS_INO_LOOKUP_PATH_MAX (4080). So the actual accessible char indexes
are in the range of [0, 4079]. Currently the code uses the define but this
represents an off-by-one.

Implications:

Size of btrfs_ioctl_ino_lookup_args is 4096, so the new byte will be
written to extra space, not some padding that could be provided by the
allocator.

btrfs-progs store the arguments on stack, but kernel does own copy of
the ioctl buffer and the off-by-one overwrite does not affect userspace,
but the ending 0 might be lost.

Kernel ioctl buffer is allocated dynamically so we're overwriting
somebody else's memory, and the ioctl is privileged if args.objectid is
not 256. Which is in most cases, but resolving a subvolume stored in
another directory will trigger that path.

Before this patch the buffer was one byte larger, but then the -1 was
not added.

Fixes: ac8e9819d71f907 ("Btrfs: add search and inode lookup ioctls")
Signed-off-by: Nikolay Borisov &lt;nborisov@suse.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
[ added implications ]
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;

Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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