fs: 9p: use strlcpy instead of strncpy

For 'NULL' terminated string, recommend always to be ended by zero.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
9p: send uevent after adding/removing mount_tag attribute

This driver adds an attribute to the existing virtio device so a CHANGE
event is required in order udev rules to make use of it. The ADD event
happens before this driver is probed and unlike a more typical driver
like a block device there isn't a higher level device to watch for.

Signed-off-by: Michael Marineau <michael.marineau@coreos.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
fs/9p: avoid accessing utsname after namespace has been torn down

During trinity fuzzing in a kvmtool guest, I stumbled across the
following:

Unable to handle kernel NULL pointer dereference at virtual address 00000004
PC is at v9fs_file_do_lock+0xc8/0x1a0
LR is at v9fs_file_do_lock+0x48/0x1a0
[<c01e2ed0>] (v9fs_file_do_lock+0xc8/0x1a0) from [<c0119154>] (locks_remove_flock+0x8c/0x124)
[<c0119154>] (locks_remove_flock+0x8c/0x124) from [<c00d9bf0>] (__fput+0x58/0x1e4)
[<c00d9bf0>] (__fput+0x58/0x1e4) from [<c0044340>] (task_work_run+0xac/0xe8)
[<c0044340>] (task_work_run+0xac/0xe8) from [<c002e36c>] (do_exit+0x6bc/0x8d8)
[<c002e36c>] (do_exit+0x6bc/0x8d8) from [<c002e674>] (do_group_exit+0x3c/0xb0)
[<c002e674>] (do_group_exit+0x3c/0xb0) from [<c002e6f8>] (__wake_up_parent+0x0/0x18)

I believe this is due to an attempt to access utsname()->nodename, after
exit_task_namespaces() has been called, leaving current->nsproxy->uts_ns
as NULL and causing the above dereference.

A similar issue was fixed for lockd in 9a1b6bf818e7 ("LOCKD: Don't call
utsname()->nodename from nlmclnt_setlockargs"), so this patch attempts
something similar for 9pfs.

Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Squashfs: sanity check information from disk

We read the size of the name from the disk, but a larger name than
expected would cause memory corruption.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Squashfs: Optimized uncompressed buffer loop

Merged the two for loops. We might get a little gain by overlapping
wait_on_bh and the memcpy operations.

Signed-off-by: Manish Sharma <manishrma@gmail.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Squashfs: fix corruption check in get_dir_index_using_name()

Patch "Squashfs: sanity check information from disk" from
Dan Carpenter adds a missing check for corruption in the
"size" field while reading the directory index from disk.

It, however, sets err to -EINVAL, this value is not used later, and
so setting it is completely redundant.  So remove it.

Errors in reading the index are deliberately non-fatal.  If we
get an error in reading the index we just return the part of the
index we have managed to read - the index isn't essential,
just quicker.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Squashfs: fix corruption checks in squashfs_lookup()

The dir_count and size fields when read from disk are sanity
checked for correctness.  However, the sanity checks only check the
values are not greater than expected.  As dir_count and size were
incorrectly defined as signed ints, this can lead to corrupted values
appearing as negative which are not trapped.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Squashfs: fix corruption checks in squashfs_readdir()

The dir_count and size fields when read from disk are sanity
checked for correctness.  However, the sanity checks only check the
values are not greater than expected.  As dir_count and size were
incorrectly defined as signed ints, this can lead to corrupted values
appearing as negative which are not trapped.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Squashfs: add corruption check in get_dir_index_using_offset()

We read the size (of the name) field from disk.  This value should
be sanity checked for correctness to avoid blindly reading
huge amounts of unnecessary data from disk on corruption.

Note, here we're not actually reading the name into a buffer, but
skipping it, and so corruption doesn't cause buffer overflow, merely
lots of unnecessary amounts of data to be read.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Squashfs: add corruption check for type in squashfs_readdir()

We read the type field from disk.  This value should be sanity
checked for correctness to avoid an out of bounds access when
reading the squashfs_filetype_table array.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Merge tag 'squashfs-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next

Pull squashfs updates from Phillip Lougher:
 "A couple of minor additional sanity check patches for corrupted
  information, and some fixes.  Apart from that there's a minor loop
  optimisation.

  These sanity checks mainly exist to trap maliciously corrupted
  filesystems either through using a deliberately modified mksquashfs,
  or where the user has deliberately chosen to generate uncompressed
  metadata and then corrupted it.

  Normally metadata in Squashfs filesystems is compressed, which means
  corruption (either accidental or malicious) is detected when trying to
  decompress the metadata.  So corrupted data does not normally get as
  far as the code paths in question here"

* tag 'squashfs-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next:
  Squashfs: add corruption check for type in squashfs_readdir()
  Squashfs: add corruption check in get_dir_index_using_offset()
  Squashfs: fix corruption checks in squashfs_readdir()
  Squashfs: fix corruption checks in squashfs_lookup()
  Squashfs: fix corruption check in get_dir_index_using_name()
  Squashfs: Optimized uncompressed buffer loop
  Squashfs: sanity check information from disk
Merge tag 'for-linus-3.12-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs

Pull 9p updates from Eric Van Hensbergen:
 "Minor 9p fixes and tweaks for 3.12 merge window

  The first fixes namespace issues which causes a kernel NULL pointer
  dereference, the second fixes uevent handling to work better with
  udev, and the third switches some code to use srlcpy instead of
  strncpy in order to be safer.

  All changes have been baking in for-next for at least 2 weeks"

* tag 'for-linus-3.12-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
  fs/9p: avoid accessing utsname after namespace has been torn down
  9p: send uevent after adding/removing mount_tag attribute
  fs: 9p: use strlcpy instead of strncpy