linux-stable.git/fs, branch v4.1.8 Linux kernel stable tree fs: create and use seq_show_option for escaping 2015-09-21T17:05:45+00:00 Kees Cook keescook@chromium.org 2015-09-04T22:44:57+00:00 d3b428f0361d6dcbe7c6665ae0a824517a0b1ca9 commit a068acf2ee77693e0bf39d6e07139ba704f461c3 upstream. Many file systems that implement the show_options hook fail to correctly escape their output which could lead to unescaped characters (e.g. new lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This could lead to confusion, spoofed entries (resulting in things like systemd issuing false d-bus "mount" notifications), and who knows what else. This looks like it would only be the root user stepping on themselves, but it's possible weird things could happen in containers or in other situations with delegated mount privileges. Here's an example using overlay with setuid fusermount trusting the contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use of "sudo" is something more sneaky: $ BASE="ovl" $ MNT="$BASE/mnt" $ LOW="$BASE/lower" $ UP="$BASE/upper" $ WORK="$BASE/work/ 0 0 none /proc fuse.pwn user_id=1000" $ mkdir -p "$LOW" "$UP" "$WORK" $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt $ cat /proc/mounts none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0 none /proc fuse.pwn user_id=1000 0 0 $ fusermount -u /proc $ cat /proc/mounts cat: /proc/mounts: No such file or directory This fixes the problem by adding new seq_show_option and seq_show_option_n helpers, and updating the vulnerable show_option handlers to use them as needed. Some, like SELinux, need to be open coded due to unusual existing escape mechanisms. [akpm@linux-foundation.org: add lost chunk, per Kees] [keescook@chromium.org: seq_show_option should be using const parameters] Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Paul Moore <paul@paul-moore.com> Cc: J. R. Okajima <hooanon05g@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a068acf2ee77693e0bf39d6e07139ba704f461c3 upstream.

Many file systems that implement the show_options hook fail to correctly
escape their output which could lead to unescaped characters (e.g.  new
lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files.  This
could lead to confusion, spoofed entries (resulting in things like
systemd issuing false d-bus "mount" notifications), and who knows what
else.  This looks like it would only be the root user stepping on
themselves, but it's possible weird things could happen in containers or
in other situations with delegated mount privileges.

Here's an example using overlay with setuid fusermount trusting the
contents of /proc/mounts (via the /etc/mtab symlink).  Imagine the use
of "sudo" is something more sneaky:

  $ BASE="ovl"
  $ MNT="$BASE/mnt"
  $ LOW="$BASE/lower"
  $ UP="$BASE/upper"
  $ WORK="$BASE/work/ 0 0
  none /proc fuse.pwn user_id=1000"
  $ mkdir -p "$LOW" "$UP" "$WORK"
  $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt
  $ cat /proc/mounts
  none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0
  none /proc fuse.pwn user_id=1000 0 0
  $ fusermount -u /proc
  $ cat /proc/mounts
  cat: /proc/mounts: No such file or directory

This fixes the problem by adding new seq_show_option and
seq_show_option_n helpers, and updating the vulnerable show_option
handlers to use them as needed.  Some, like SELinux, need to be open
coded due to unusual existing escape mechanisms.

[akpm@linux-foundation.org: add lost chunk, per Kees]
[keescook@chromium.org: seq_show_option should be using const parameters]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Jan Kara <jack@suse.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hpfs: update ctime and mtime on directory modification 2015-09-21T17:05:44+00:00 Mikulas Patocka mikulas@twibright.com 2015-09-02T20:51:53+00:00 213abaf9525398c7dd34012b29274261dd8cd797 commit f49a26e7718dd30b49e3541e3e25aecf5e7294e2 upstream. Update ctime and mtime when a directory is modified. (though OS/2 doesn't update them anyway) Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f49a26e7718dd30b49e3541e3e25aecf5e7294e2 upstream.

Update ctime and mtime when a directory is modified. (though OS/2 doesn't
update them anyway)

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs: Set the size of empty dirs to 0. 2015-09-21T17:05:44+00:00 Eric W. Biederman ebiederm@xmission.com 2015-08-12T20:00:12+00:00 16e327d319bf3cbdd507693ed18792cda3af3324 commit 4b75de8615050c1b0dd8d7794838c42f74ed36ba upstream. Before the make_empty_dir_inode calls were introduce into proc, sysfs, and sysctl those directories when stated reported an i_size of 0. make_empty_dir_inode started reporting an i_size of 2. At least one userspace application depended on stat returning i_size of 0. So modify make_empty_dir_inode to cause an i_size of 0 to be reported for these directories. Reported-by: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4b75de8615050c1b0dd8d7794838c42f74ed36ba upstream.

Before the make_empty_dir_inode calls were introduce into proc, sysfs,
and sysctl those directories when stated reported an i_size of 0.
make_empty_dir_inode started reporting an i_size of 2.  At least one
userspace application depended on stat returning i_size of 0.  So
modify make_empty_dir_inode to cause an i_size of 0 to be reported for
these directories.

Reported-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xfs: Fix file type directory corruption for btree directories 2015-09-21T17:05:37+00:00 Jan Kara jack@suse.com 2015-08-25T00:05:13+00:00 533f267763456f75d57bd590830629bf28fe3d8c commit 037542345a82aaaa228ec280fe6ddff1568d169f upstream. Users have occasionally reported that file type for some directory entries is wrong. This mostly happened after updating libraries some libraries. After some debugging the problem was traced down to xfs_dir2_node_replace(). The function uses args->filetype as a file type to store in the replaced directory entry however it also calls xfs_da3_node_lookup_int() which will store file type of the current directory entry in args->filetype. Thus we fail to change file type of a directory entry to a proper type. Fix the problem by storing new file type in a local variable before calling xfs_da3_node_lookup_int(). Reported-by: Giacomo Comes <comes@naic.edu> Signed-off-by: Jan Kara <jack@suse.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 037542345a82aaaa228ec280fe6ddff1568d169f upstream.

Users have occasionally reported that file type for some directory
entries is wrong. This mostly happened after updating libraries some
libraries. After some debugging the problem was traced down to
xfs_dir2_node_replace(). The function uses args->filetype as a file type
to store in the replaced directory entry however it also calls
xfs_da3_node_lookup_int() which will store file type of the current
directory entry in args->filetype. Thus we fail to change file type of a
directory entry to a proper type.

Fix the problem by storing new file type in a local variable before
calling xfs_da3_node_lookup_int().

Reported-by: Giacomo Comes <comes@naic.edu>
Signed-off-by: Jan Kara <jack@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xfs: Fix xfs_attr_leafblock definition 2015-09-21T17:05:37+00:00 Jan Kara jack@suse.com 2015-08-19T00:34:32+00:00 39516016709f4bf72d6e4c12089bbae7b1432ba7 commit ffeecc5213024ae663377b442eedcfbacf6d0c5d upstream. struct xfs_attr_leafblock contains 'entries' array which is declared with size 1 altough it can in fact contain much more entries. Since this array is followed by further struct members, gcc (at least in version 4.8.3) thinks that the array has the fixed size of 1 element and thus may optimize away all accesses beyond the end of array resulting in non-working code. This problem was only observed with userspace code in xfsprogs, however it's better to be safe in kernel as well and have matching kernel and xfsprogs definitions. Signed-off-by: Jan Kara <jack@suse.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ffeecc5213024ae663377b442eedcfbacf6d0c5d upstream.

struct xfs_attr_leafblock contains 'entries' array which is declared
with size 1 altough it can in fact contain much more entries. Since this
array is followed by further struct members, gcc (at least in version
4.8.3) thinks that the array has the fixed size of 1 element and thus
may optimize away all accesses beyond the end of array resulting in
non-working code. This problem was only observed with userspace code in
xfsprogs, however it's better to be safe in kernel as well and have
matching kernel and xfsprogs definitions.

Signed-off-by: Jan Kara <jack@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
libxfs: readahead of dir3 data blocks should use the read verifier 2015-09-21T17:05:36+00:00 Darrick J. Wong darrick.wong@oracle.com 2015-08-19T00:33:58+00:00 16f47b6ab239970067885a9384c456c6b530bb12 commit 2f123bce18943fff819bc10f8868ffb9149fc622 upstream. In the dir3 data block readahead function, use the regular read verifier to check the block's CRC and spot-check the block contents instead of directly calling only the spot-checking routine. This prevents corrupted directory data blocks from being read into the kernel, which can lead to garbage ls output and directory loops (if say one of the entries contains slashes and other junk). Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2f123bce18943fff819bc10f8868ffb9149fc622 upstream.

In the dir3 data block readahead function, use the regular read
verifier to check the block's CRC and spot-check the block contents
instead of directly calling only the spot-checking routine.  This
prevents corrupted directory data blocks from being read into the
kernel, which can lead to garbage ls output and directory loops (if
say one of the entries contains slashes and other junk).

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nfsd: do nfs4_check_fh in nfs4_check_file instead of nfs4_check_olstateid 2015-08-17T03:52:27+00:00 Jeff Layton jlayton@poochiereds.net 2015-07-30T10:57:46+00:00 1ccdd6c6e9a342c2ed4ced38faa67303226a2a6a commit 8fcd461db7c09337b6d2e22d25eb411123f379e3 upstream. Currently, preprocess_stateid_op calls nfs4_check_olstateid which verifies that the open stateid corresponds to the current filehandle in the call by calling nfs4_check_fh. If the stateid is a NFS4_DELEG_STID however, then no such check is done. This could cause incorrect enforcement of permissions, because the nfsd_permission() call in nfs4_check_file uses current the current filehandle, but any subsequent IO operation will use the file descriptor in the stateid. Move the call to nfs4_check_fh into nfs4_check_file instead so that it can be done for all stateid types. Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> [bfields: moved fh check to avoid NULL deref in special stateid case] Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8fcd461db7c09337b6d2e22d25eb411123f379e3 upstream.

Currently, preprocess_stateid_op calls nfs4_check_olstateid which
verifies that the open stateid corresponds to the current filehandle in the
call by calling nfs4_check_fh.

If the stateid is a NFS4_DELEG_STID however, then no such check is done.
This could cause incorrect enforcement of permissions, because the
nfsd_permission() call in nfs4_check_file uses current the current
filehandle, but any subsequent IO operation will use the file descriptor
in the stateid.

Move the call to nfs4_check_fh into nfs4_check_file instead so that it
can be done for all stateid types.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
[bfields: moved fh check to avoid NULL deref in special stateid case]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nfsd: refactor nfs4_preprocess_stateid_op 2015-08-17T03:52:26+00:00 Christoph Hellwig hch@lst.de 2015-06-18T14:44:59+00:00 3b5c2aed0e5557c6bc4a305e7627a16a764b4cdb commit a0649b2d3fffb1cde8745568c767f3a55a3462bc upstream. Split out two self contained helpers to make the function more readable. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Cc: Jeff Layton <jlayton@poochiereds.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a0649b2d3fffb1cde8745568c767f3a55a3462bc upstream.

Split out two self contained helpers to make the function more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Cc: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
signalfd: fix information leak in signalfd_copyinfo 2015-08-17T03:52:25+00:00 Amanieu d'Antras amanieu@gmail.com 2015-08-06T22:46:33+00:00 8a97f0e58abc93f67f1f6ca571e4ff758739cedf commit 3ead7c52bdb0ab44f4bb1feed505a8323cc12ba7 upstream. This function may copy the si_addr_lsb field to user mode when it hasn't been initialized, which can leak kernel stack data to user mode. Just checking the value of si_code is insufficient because the same si_code value is shared between multiple signals. This is solved by checking the value of si_signo in addition to si_code. Signed-off-by: Amanieu d'Antras <amanieu@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3ead7c52bdb0ab44f4bb1feed505a8323cc12ba7 upstream.

This function may copy the si_addr_lsb field to user mode when it hasn't
been initialized, which can leak kernel stack data to user mode.

Just checking the value of si_code is insufficient because the same
si_code value is shared between multiple signals.  This is solved by
checking the value of si_signo in addition to si_code.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nfsd: Drop BUG_ON and ignore SECLABEL on absent filesystem 2015-08-17T03:52:22+00:00 Kinglong Mee kinglongmee@gmail.com 2015-07-07T02:16:37+00:00 c7e6f05156402364f34669e0fa6fd69b834f994b commit c2227a39a078473115910512aa0f8d53bd915e60 upstream. On an absent filesystem (one served by another server), we need to be able to handle requests for certain attributest (like fs_locations, so the client can find out which server does have the filesystem), but others we can't. We forgot to take that into account when adding another attribute bitmask work for the SECURITY_LABEL attribute. There an export entry with the "refer" option can result in: [ 88.414272] kernel BUG at fs/nfsd/nfs4xdr.c:2249! [ 88.414828] invalid opcode: 0000 [#1] SMP [ 88.415368] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache nfsd xfs libcrc32c iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi iosf_mbi ppdev btrfs coretemp crct10dif_pclmul crc32_pclmul crc32c_intel xor ghash_clmulni_intel raid6_pq vmw_balloon parport_pc parport i2c_piix4 shpchp vmw_vmci acpi_cpufreq auth_rpcgss nfs_acl lockd grace sunrpc vmwgfx drm_kms_helper ttm drm mptspi mptscsih serio_raw mptbase e1000 scsi_transport_spi ata_generic pata_acpi [last unloaded: nfsd] [ 88.417827] CPU: 0 PID: 2116 Comm: nfsd Not tainted 4.0.7-300.fc22.x86_64 #1 [ 88.418448] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/20/2014 [ 88.419093] task: ffff880079146d50 ti: ffff8800785d8000 task.ti: ffff8800785d8000 [ 88.419729] RIP: 0010:[<ffffffffa04b3c10>] [<ffffffffa04b3c10>] nfsd4_encode_fattr+0x820/0x1f00 [nfsd] [ 88.420376] RSP: 0000:ffff8800785db998 EFLAGS: 00010206 [ 88.421027] RAX: 0000000000000001 RBX: 000000000018091a RCX: ffff88006668b980 [ 88.421676] RDX: 00000000fffef7fc RSI: 0000000000000000 RDI: ffff880078d05000 [ 88.422315] RBP: ffff8800785dbb58 R08: ffff880078d043f8 R09: ffff880078d4a000 [ 88.422968] R10: 0000000000010000 R11: 0000000000000002 R12: 0000000000b0a23a [ 88.423612] R13: ffff880078d05000 R14: ffff880078683100 R15: ffff88006668b980 [ 88.424295] FS: 0000000000000000(0000) GS:ffff88007c600000(0000) knlGS:0000000000000000 [ 88.424944] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 88.425597] CR2: 00007f40bc370f90 CR3: 0000000035af5000 CR4: 00000000001407f0 [ 88.426285] Stack: [ 88.426921] ffff8800785dbaa8 ffffffffa049e4af ffff8800785dba08 ffffffff813298f0 [ 88.427585] ffff880078683300 ffff8800769b0de8 0000089d00000001 0000000087f805e0 [ 88.428228] ffff880000000000 ffff880079434a00 0000000000000000 ffff88006668b980 [ 88.428877] Call Trace: [ 88.429527] [<ffffffffa049e4af>] ? exp_get_by_name+0x7f/0xb0 [nfsd] [ 88.430168] [<ffffffff813298f0>] ? inode_doinit_with_dentry+0x210/0x6a0 [ 88.430807] [<ffffffff8123833e>] ? d_lookup+0x2e/0x60 [ 88.431449] [<ffffffff81236133>] ? dput+0x33/0x230 [ 88.432097] [<ffffffff8123f214>] ? mntput+0x24/0x40 [ 88.432719] [<ffffffff812272b2>] ? path_put+0x22/0x30 [ 88.433340] [<ffffffffa049ac87>] ? nfsd_cross_mnt+0xb7/0x1c0 [nfsd] [ 88.433954] [<ffffffffa04b54e0>] nfsd4_encode_dirent+0x1b0/0x3d0 [nfsd] [ 88.434601] [<ffffffffa04b5330>] ? nfsd4_encode_getattr+0x40/0x40 [nfsd] [ 88.435172] [<ffffffffa049c991>] nfsd_readdir+0x1c1/0x2a0 [nfsd] [ 88.435710] [<ffffffffa049a530>] ? nfsd_direct_splice_actor+0x20/0x20 [nfsd] [ 88.436447] [<ffffffffa04abf30>] nfsd4_encode_readdir+0x120/0x220 [nfsd] [ 88.437011] [<ffffffffa04b58cd>] nfsd4_encode_operation+0x7d/0x190 [nfsd] [ 88.437566] [<ffffffffa04aa6dd>] nfsd4_proc_compound+0x24d/0x6f0 [nfsd] [ 88.438157] [<ffffffffa0496103>] nfsd_dispatch+0xc3/0x220 [nfsd] [ 88.438680] [<ffffffffa006f0cb>] svc_process_common+0x43b/0x690 [sunrpc] [ 88.439192] [<ffffffffa0070493>] svc_process+0x103/0x1b0 [sunrpc] [ 88.439694] [<ffffffffa0495a57>] nfsd+0x117/0x190 [nfsd] [ 88.440194] [<ffffffffa0495940>] ? nfsd_destroy+0x90/0x90 [nfsd] [ 88.440697] [<ffffffff810bb728>] kthread+0xd8/0xf0 [ 88.441260] [<ffffffff810bb650>] ? kthread_worker_fn+0x180/0x180 [ 88.441762] [<ffffffff81789e58>] ret_from_fork+0x58/0x90 [ 88.442322] [<ffffffff810bb650>] ? kthread_worker_fn+0x180/0x180 [ 88.442879] Code: 0f 84 93 05 00 00 83 f8 ea c7 85 a0 fe ff ff 00 00 27 30 0f 84 ba fe ff ff 85 c0 0f 85 a5 fe ff ff e9 e3 f9 ff ff 0f 1f 44 00 00 <0f> 0b 66 0f 1f 44 00 00 be 04 00 00 00 4c 89 ef 4c 89 8d 68 fe [ 88.444052] RIP [<ffffffffa04b3c10>] nfsd4_encode_fattr+0x820/0x1f00 [nfsd] [ 88.444658] RSP <ffff8800785db998> [ 88.445232] ---[ end trace 6cb9d0487d94a29f ]--- Signed-off-by: Kinglong Mee <kinglongmee@gmail.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c2227a39a078473115910512aa0f8d53bd915e60 upstream.

On an absent filesystem (one served by another server), we need to be
able to handle requests for certain attributest (like fs_locations, so
the client can find out which server does have the filesystem), but
others we can't.

We forgot to take that into account when adding another attribute
bitmask work for the SECURITY_LABEL attribute.

There an export entry with the "refer" option can result in:

[   88.414272] kernel BUG at fs/nfsd/nfs4xdr.c:2249!
[   88.414828] invalid opcode: 0000 [#1] SMP
[   88.415368] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache nfsd xfs libcrc32c iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi iosf_mbi ppdev btrfs coretemp crct10dif_pclmul crc32_pclmul crc32c_intel xor ghash_clmulni_intel raid6_pq vmw_balloon parport_pc parport i2c_piix4 shpchp vmw_vmci acpi_cpufreq auth_rpcgss nfs_acl lockd grace sunrpc vmwgfx drm_kms_helper ttm drm mptspi mptscsih serio_raw mptbase e1000 scsi_transport_spi ata_generic pata_acpi [last unloaded: nfsd]
[   88.417827] CPU: 0 PID: 2116 Comm: nfsd Not tainted 4.0.7-300.fc22.x86_64 #1
[   88.418448] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/20/2014
[   88.419093] task: ffff880079146d50 ti: ffff8800785d8000 task.ti: ffff8800785d8000
[   88.419729] RIP: 0010:[<ffffffffa04b3c10>]  [<ffffffffa04b3c10>] nfsd4_encode_fattr+0x820/0x1f00 [nfsd]
[   88.420376] RSP: 0000:ffff8800785db998  EFLAGS: 00010206
[   88.421027] RAX: 0000000000000001 RBX: 000000000018091a RCX: ffff88006668b980
[   88.421676] RDX: 00000000fffef7fc RSI: 0000000000000000 RDI: ffff880078d05000
[   88.422315] RBP: ffff8800785dbb58 R08: ffff880078d043f8 R09: ffff880078d4a000
[   88.422968] R10: 0000000000010000 R11: 0000000000000002 R12: 0000000000b0a23a
[   88.423612] R13: ffff880078d05000 R14: ffff880078683100 R15: ffff88006668b980
[   88.424295] FS:  0000000000000000(0000) GS:ffff88007c600000(0000) knlGS:0000000000000000
[   88.424944] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   88.425597] CR2: 00007f40bc370f90 CR3: 0000000035af5000 CR4: 00000000001407f0
[   88.426285] Stack:
[   88.426921]  ffff8800785dbaa8 ffffffffa049e4af ffff8800785dba08 ffffffff813298f0
[   88.427585]  ffff880078683300 ffff8800769b0de8 0000089d00000001 0000000087f805e0
[   88.428228]  ffff880000000000 ffff880079434a00 0000000000000000 ffff88006668b980
[   88.428877] Call Trace:
[   88.429527]  [<ffffffffa049e4af>] ? exp_get_by_name+0x7f/0xb0 [nfsd]
[   88.430168]  [<ffffffff813298f0>] ? inode_doinit_with_dentry+0x210/0x6a0
[   88.430807]  [<ffffffff8123833e>] ? d_lookup+0x2e/0x60
[   88.431449]  [<ffffffff81236133>] ? dput+0x33/0x230
[   88.432097]  [<ffffffff8123f214>] ? mntput+0x24/0x40
[   88.432719]  [<ffffffff812272b2>] ? path_put+0x22/0x30
[   88.433340]  [<ffffffffa049ac87>] ? nfsd_cross_mnt+0xb7/0x1c0 [nfsd]
[   88.433954]  [<ffffffffa04b54e0>] nfsd4_encode_dirent+0x1b0/0x3d0 [nfsd]
[   88.434601]  [<ffffffffa04b5330>] ? nfsd4_encode_getattr+0x40/0x40 [nfsd]
[   88.435172]  [<ffffffffa049c991>] nfsd_readdir+0x1c1/0x2a0 [nfsd]
[   88.435710]  [<ffffffffa049a530>] ? nfsd_direct_splice_actor+0x20/0x20 [nfsd]
[   88.436447]  [<ffffffffa04abf30>] nfsd4_encode_readdir+0x120/0x220 [nfsd]
[   88.437011]  [<ffffffffa04b58cd>] nfsd4_encode_operation+0x7d/0x190 [nfsd]
[   88.437566]  [<ffffffffa04aa6dd>] nfsd4_proc_compound+0x24d/0x6f0 [nfsd]
[   88.438157]  [<ffffffffa0496103>] nfsd_dispatch+0xc3/0x220 [nfsd]
[   88.438680]  [<ffffffffa006f0cb>] svc_process_common+0x43b/0x690 [sunrpc]
[   88.439192]  [<ffffffffa0070493>] svc_process+0x103/0x1b0 [sunrpc]
[   88.439694]  [<ffffffffa0495a57>] nfsd+0x117/0x190 [nfsd]
[   88.440194]  [<ffffffffa0495940>] ? nfsd_destroy+0x90/0x90 [nfsd]
[   88.440697]  [<ffffffff810bb728>] kthread+0xd8/0xf0
[   88.441260]  [<ffffffff810bb650>] ? kthread_worker_fn+0x180/0x180
[   88.441762]  [<ffffffff81789e58>] ret_from_fork+0x58/0x90
[   88.442322]  [<ffffffff810bb650>] ? kthread_worker_fn+0x180/0x180
[   88.442879] Code: 0f 84 93 05 00 00 83 f8 ea c7 85 a0 fe ff ff 00 00 27 30 0f 84 ba fe ff ff 85 c0 0f 85 a5 fe ff ff e9 e3 f9 ff ff 0f 1f 44 00 00 <0f> 0b 66 0f 1f 44 00 00 be 04 00 00 00 4c 89 ef 4c 89 8d 68 fe
[   88.444052] RIP  [<ffffffffa04b3c10>] nfsd4_encode_fattr+0x820/0x1f00 [nfsd]
[   88.444658]  RSP <ffff8800785db998>
[   88.445232] ---[ end trace 6cb9d0487d94a29f ]---

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>