Commit Graph

440 Commits

Author SHA1 Message Date
Linus Torvalds
e2e091fd99 Merge tag 'ecryptfs-3.9-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs
Pull ecryptfs fixes from Tyler Hicks:
 "Minor code cleanups and new Kconfig option to disable /dev/ecryptfs

  The code cleanups fix up W=1 compiler warnings and some unnecessary
  checks.  The new Kconfig option, defaulting to N, allows the rarely
  used eCryptfs kernel to userspace communication channel to be compiled
  out.  This may be the first step in it being eventually removed."

Hmm.  I'm not sure whether these should be called "fixes", and it
probably should have gone in the merge window.  But I'll let it slide.

* tag 'ecryptfs-3.9-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs:
  eCryptfs: allow userspace messaging to be disabled
  eCryptfs: Fix redundant error check on ecryptfs_find_daemon_by_euid()
  ecryptfs: ecryptfs_msg_ctx_alloc_to_free(): remove kfree() redundant null check
  eCryptfs: decrypt_pki_encrypted_session_key(): remove kfree() redundant null check
  eCryptfs: remove unneeded checks in virt_to_scatterlist()
  eCryptfs: Fix -Wmissing-prototypes warnings
  eCryptfs: Fix -Wunused-but-set-variable warnings
  eCryptfs: initialize payload_len in keystore.c
2013-03-07 12:47:24 -08:00
Kees Cook
290502bee2 eCryptfs: allow userspace messaging to be disabled
When the userspace messaging (for the less common case of userspace key
wrap/unwrap via ecryptfsd) is not needed, allow eCryptfs to build with
it removed. This saves on kernel code size and reduces potential attack
surface by removing the /dev/ecryptfs node.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-03-03 23:59:59 -08:00
Sasha Levin
b67bfe0d42 hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:24 -08:00
Tyler Hicks
1111eae90f eCryptfs: Fix redundant error check on ecryptfs_find_daemon_by_euid()
It is sufficient to check the return code of
ecryptfs_find_daemon_by_euid(). If it returns 0, it always sets the
daemon pointer to point to a valid ecryptfs_daemon.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reported-by: Kees Cook <keescook@chromium.org>
2013-02-27 11:41:18 -08:00
Linus Torvalds
d895cb1af1 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs pile (part one) from Al Viro:
 "Assorted stuff - cleaning namei.c up a bit, fixing ->d_name/->d_parent
  locking violations, etc.

  The most visible changes here are death of FS_REVAL_DOT (replaced with
  "has ->d_weak_revalidate()") and a new helper getting from struct file
  to inode.  Some bits of preparation to xattr method interface changes.

  Misc patches by various people sent this cycle *and* ocfs2 fixes from
  several cycles ago that should've been upstream right then.

  PS: the next vfs pile will be xattr stuff."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (46 commits)
  saner proc_get_inode() calling conventions
  proc: avoid extra pde_put() in proc_fill_super()
  fs: change return values from -EACCES to -EPERM
  fs/exec.c: make bprm_mm_init() static
  ocfs2/dlm: use GFP_ATOMIC inside a spin_lock
  ocfs2: fix possible use-after-free with AIO
  ocfs2: Fix oops in ocfs2_fast_symlink_readpage() code path
  get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero
  target: writev() on single-element vector is pointless
  export kernel_write(), convert open-coded instances
  fs: encode_fh: return FILEID_INVALID if invalid fid_type
  kill f_vfsmnt
  vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op
  nfsd: handle vfs_getattr errors in acl protocol
  switch vfs_getattr() to struct path
  default SET_PERSONALITY() in linux/elf.h
  ceph: prepopulate inodes only when request is aborted
  d_hash_and_lookup(): export, switch open-coded instances
  9p: switch v9fs_set_create_acl() to inode+fid, do it before d_instantiate()
  9p: split dropping the acls from v9fs_set_create_acl()
  ...
2013-02-26 20:16:07 -08:00
Al Viro
7bb307e894 export kernel_write(), convert open-coded instances
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-26 02:46:11 -05:00
Al Viro
3dadecce20 switch vfs_getattr() to struct path
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-26 02:46:08 -05:00
Al Viro
496ad9aa8e new helper: file_inode(file)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22 23:31:31 -05:00
Tim Gardner
1101d58669 ecryptfs: ecryptfs_msg_ctx_alloc_to_free(): remove kfree() redundant null check
smatch analysis:

fs/ecryptfs/messaging.c:101 ecryptfs_msg_ctx_alloc_to_free() info:
 redundant null check on msg_ctx->msg calling kfree()

Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Cc: ecryptfs@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-02-12 10:09:11 -08:00
Tim Gardner
3a46741804 eCryptfs: decrypt_pki_encrypted_session_key(): remove kfree() redundant null check
smatch analysis:

fs/ecryptfs/keystore.c:1206 decrypt_pki_encrypted_session_key() info:
 redundant null check on msg calling kfree()

Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Cc: ecryptfs@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-02-12 10:06:01 -08:00
Dan Carpenter
a07c48ad5b eCryptfs: remove unneeded checks in virt_to_scatterlist()
This is always called with a valid "sg" pointer.  My static checker
complains because the call to sg_init_table() dereferences "sg" before
we reach the checks.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-01-28 16:38:37 -08:00
Tyler Hicks
111d61a25e eCryptfs: Fix -Wmissing-prototypes warnings
Mark two inode operation fuctions as static. Fixes warnings when
building with W=1.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-01-17 12:20:47 -08:00
Tyler Hicks
bbcb03e3ce eCryptfs: Fix -Wunused-but-set-variable warnings
These two variables are no longer used and can be removed. Fixes
warnings when building with W=1.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-01-17 11:36:10 -08:00
Simon Que
fa5199648e eCryptfs: initialize payload_len in keystore.c
This is meant to remove a compiler warning.  It should not make any
functional change.

payload_len should be initialized when it is passed to
write_tag_64_packet() as a pointer.  If that call fails, this function
should return early, and payload_len won't be used.

Signed-off-by: Simon Que <sque@chromium.org>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2013-01-17 11:31:25 -08:00
Kees Cook
336d6d0323 fs/ecryptfs: remove depends on CONFIG_EXPERIMENTAL
The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.

CC: Tyler Hicks <tyhicks@canonical.com>
CC: Dustin Kirkland <dustin.kirkland@gazzang.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Tyler Hicks <tyhicks@canonical.com>
2013-01-11 11:39:04 -08:00
Cong Ding
37028758f9 fs/ecryptfs/crypto.c: make ecryptfs_encode_for_filename() static
the function ecryptfs_encode_for_filename() is only used in this file

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2012-12-18 10:10:13 -06:00
Wei Yongjun
8bbca57cff eCryptfs: fix to use list_for_each_entry_safe() when delete items
Since we will be removing items off the list using list_del() we need
to use a safer version of the list_for_each_entry() macro aptly named
list_for_each_entry_safe(). We should use the safe macro if the loop
involves deletions of items.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
[tyhicks: Fixed compiler err - missing list_for_each_entry_safe() param]
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2012-12-18 10:07:29 -06:00
Li Wang
e4bc6522d5 eCryptfs: Avoid unnecessary disk read and data decryption during writing
ecryptfs_write_begin grabs a page from page cache for writing.
If the page contains invalid data, or data older than the
counterpart on the disk, eCryptfs will read out the
corresponing data from the disk into the page, decrypt them,
then perform writing. However, for this page, if the length
of the data to be written into is equal to page size,
that means the whole page of data will be overwritten,
in which case, it does not matter whatever the data were before,
it is beneficial to perform writing directly rather than bothering
to read and decrypt first.

With this optimization, according to our test on a machine with
Intel Core 2 Duo processor, iozone 'write' operation on an existing
file with write size being multiple of page size will enjoy a steady
3x speedup.

Signed-off-by: Li Wang <wangli@kylinos.com.cn>
Signed-off-by: Yunchuan Wen <wenyunchuan@kylinos.com.cn>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2012-11-07 17:56:16 -08:00
Linus Torvalds
aab174f0df Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs update from Al Viro:

 - big one - consolidation of descriptor-related logics; almost all of
   that is moved to fs/file.c

   (BTW, I'm seriously tempted to rename the result to fd.c.  As it is,
   we have a situation when file_table.c is about handling of struct
   file and file.c is about handling of descriptor tables; the reasons
   are historical - file_table.c used to be about a static array of
   struct file we used to have way back).

   A lot of stray ends got cleaned up and converted to saner primitives,
   disgusting mess in android/binder.c is still disgusting, but at least
   doesn't poke so much in descriptor table guts anymore.  A bunch of
   relatively minor races got fixed in process, plus an ext4 struct file
   leak.

 - related thing - fget_light() partially unuglified; see fdget() in
   there (and yes, it generates the code as good as we used to have).

 - also related - bits of Cyrill's procfs stuff that got entangled into
   that work; _not_ all of it, just the initial move to fs/proc/fd.c and
   switch of fdinfo to seq_file.

 - Alex's fs/coredump.c spiltoff - the same story, had been easier to
   take that commit than mess with conflicts.  The rest is a separate
   pile, this was just a mechanical code movement.

 - a few misc patches all over the place.  Not all for this cycle,
   there'll be more (and quite a few currently sit in akpm's tree)."

Fix up trivial conflicts in the android binder driver, and some fairly
simple conflicts due to two different changes to the sock_alloc_file()
interface ("take descriptor handling from sock_alloc_file() to callers"
vs "net: Providing protocol type via system.sockprotoname xattr of
/proc/PID/fd entries" adding a dentry name to the socket)

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (72 commits)
  MAX_LFS_FILESIZE should be a loff_t
  compat: fs: Generic compat_sys_sendfile implementation
  fs: push rcu_barrier() from deactivate_locked_super() to filesystems
  btrfs: reada_extent doesn't need kref for refcount
  coredump: move core dump functionality into its own file
  coredump: prevent double-free on an error path in core dumper
  usb/gadget: fix misannotations
  fcntl: fix misannotations
  ceph: don't abuse d_delete() on failure exits
  hypfs: ->d_parent is never NULL or negative
  vfs: delete surplus inode NULL check
  switch simple cases of fget_light to fdget
  new helpers: fdget()/fdput()
  switch o2hb_region_dev_write() to fget_light()
  proc_map_files_readdir(): don't bother with grabbing files
  make get_file() return its argument
  vhost_set_vring(): turn pollstart/pollstop into bool
  switch prctl_set_mm_exe_file() to fget_light()
  switch xfs_find_handle() to fget_light()
  switch xfs_swapext() to fget_light()
  ...
2012-10-02 20:25:04 -07:00
Kirill A. Shutemov
8c0a853770 fs: push rcu_barrier() from deactivate_locked_super() to filesystems
There's no reason to call rcu_barrier() on every
deactivate_locked_super().  We only need to make sure that all delayed rcu
free inodes are flushed before we destroy related cache.

Removing rcu_barrier() from deactivate_locked_super() affects some fast
paths.  E.g.  on my machine exit_group() of a last process in IPC
namespace takes 0.07538s.  rcu_barrier() takes 0.05188s of that time.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-10-02 21:35:55 -04:00
Linus Torvalds
437589a74b Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace changes from Eric Biederman:
 "This is a mostly modest set of changes to enable basic user namespace
  support.  This allows the code to code to compile with user namespaces
  enabled and removes the assumption there is only the initial user
  namespace.  Everything is converted except for the most complex of the
  filesystems: autofs4, 9p, afs, ceph, cifs, coda, fuse, gfs2, ncpfs,
  nfs, ocfs2 and xfs as those patches need a bit more review.

  The strategy is to push kuid_t and kgid_t values are far down into
  subsystems and filesystems as reasonable.  Leaving the make_kuid and
  from_kuid operations to happen at the edge of userspace, as the values
  come off the disk, and as the values come in from the network.
  Letting compile type incompatible compile errors (present when user
  namespaces are enabled) guide me to find the issues.

  The most tricky areas have been the places where we had an implicit
  union of uid and gid values and were storing them in an unsigned int.
  Those places were converted into explicit unions.  I made certain to
  handle those places with simple trivial patches.

  Out of that work I discovered we have generic interfaces for storing
  quota by projid.  I had never heard of the project identifiers before.
  Adding full user namespace support for project identifiers accounts
  for most of the code size growth in my git tree.

  Ultimately there will be work to relax privlige checks from
  "capable(FOO)" to "ns_capable(user_ns, FOO)" where it is safe allowing
  root in a user names to do those things that today we only forbid to
  non-root users because it will confuse suid root applications.

  While I was pushing kuid_t and kgid_t changes deep into the audit code
  I made a few other cleanups.  I capitalized on the fact we process
  netlink messages in the context of the message sender.  I removed
  usage of NETLINK_CRED, and started directly using current->tty.

  Some of these patches have also made it into maintainer trees, with no
  problems from identical code from different trees showing up in
  linux-next.

  After reading through all of this code I feel like I might be able to
  win a game of kernel trivial pursuit."

Fix up some fairly trivial conflicts in netfilter uid/git logging code.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (107 commits)
  userns: Convert the ufs filesystem to use kuid/kgid where appropriate
  userns: Convert the udf filesystem to use kuid/kgid where appropriate
  userns: Convert ubifs to use kuid/kgid
  userns: Convert squashfs to use kuid/kgid where appropriate
  userns: Convert reiserfs to use kuid and kgid where appropriate
  userns: Convert jfs to use kuid/kgid where appropriate
  userns: Convert jffs2 to use kuid and kgid where appropriate
  userns: Convert hpfs to use kuid and kgid where appropriate
  userns: Convert btrfs to use kuid/kgid where appropriate
  userns: Convert bfs to use kuid/kgid where appropriate
  userns: Convert affs to use kuid/kgid wherwe appropriate
  userns: On alpha modify linux_to_osf_stat to use convert from kuids and kgids
  userns: On ia64 deal with current_uid and current_gid being kuid and kgid
  userns: On ppc convert current_uid from a kuid before printing.
  userns: Convert s390 getting uid and gid system calls to use kuid and kgid
  userns: Convert s390 hypfs to use kuid and kgid where appropriate
  userns: Convert binder ipc to use kuids
  userns: Teach security_path_chown to take kuids and kgids
  userns: Add user namespace support to IMA
  userns: Convert EVM to deal with kuids and kgids in it's hmac computation
  ...
2012-10-02 11:11:09 -07:00
Eric W. Biederman
cdf8c58a35 userns: Convert ecryptfs to use kuid/kgid where appropriate
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-09-21 03:13:09 -07:00
Tyler Hicks
8335eafc28 eCryptfs: Copy up attributes of the lower target inode after rename
After calling into the lower filesystem to do a rename, the lower target
inode's attributes were not copied up to the eCryptfs target inode. This
resulted in the eCryptfs target inode staying around, rather than being
evicted, because i_nlink was not updated for the eCryptfs inode. This
also meant that eCryptfs didn't do the final iput() on the lower target
inode so it stayed around, as well. This would result in a failure to
free up space occupied by the target file in the rename() operation.
Both target inodes would eventually be evicted when the eCryptfs
filesystem was unmounted.

This patch calls fsstack_copy_attr_all() after the lower filesystem
does its ->rename() so that important inode attributes, such as i_nlink,
are updated at the eCryptfs layer. ecryptfs_evict_inode() is now called
and eCryptfs can drop its final reference on the lower inode.

http://launchpad.net/bugs/561129

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Tested-by: Colin Ian King <colin.king@canonical.com>
Cc: <stable@vger.kernel.org> [2.6.39+]
2012-09-14 09:36:03 -07:00
Tyler Hicks
64e6651dcc eCryptfs: Call lower ->flush() from ecryptfs_flush()
Since eCryptfs only calls fput() on the lower file in
ecryptfs_release(), eCryptfs should call the lower filesystem's
->flush() from ecryptfs_flush().

If the lower filesystem implements ->flush(), then eCryptfs should try
to flush out any dirty pages prior to calling the lower ->flush(). If
the lower filesystem does not implement ->flush(), then eCryptfs has no
need to do anything in ecryptfs_flush() since dirty pages are now
written out to the lower filesystem in ecryptfs_release().

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2012-09-14 09:35:54 -07:00
Tyler Hicks
7149f2558d eCryptfs: Write out all dirty pages just before releasing the lower file
Fixes a regression caused by:

821f749 eCryptfs: Revert to a writethrough cache model

That patch reverted some code (specifically, 32001d6f) that was
necessary to properly handle open() -> mmap() -> close() -> dirty pages
-> munmap(), because the lower file could be closed before the dirty
pages are written out.

Rather than reapplying 32001d6f, this approach is a better way of
ensuring that the lower file is still open in order to handle writing
out the dirty pages. It is called from ecryptfs_release(), while we have
a lock on the lower file pointer, just before the lower file gets the
final fput() and we overwrite the pointer.

https://launchpad.net/bugs/1047261

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reported-by: Artemy Tregubenko <me@arty.name>
Tested-by: Artemy Tregubenko <me@arty.name>
Tested-by: Colin Ian King <colin.king@canonical.com>
2012-09-14 09:11:29 -07:00