linux-toradex.git/fs, branch v3.2.37

epoll: prevent missed events on EPOLL_CTL_MOD

2013-01-16T01:13:22+00:00

commit 128dd1759d96ad36c379240f8b9463e8acfd37a1 upstream.

EPOLL_CTL_MOD sets the interest mask before calling f_op->poll() to
ensure events are not missed.  Since the modifications to the interest
mask are not protected by the same lock as ep_poll_callback, we need to
ensure the change is visible to other CPUs calling ep_poll_callback.

We also need to ensure f_op->poll() has an up-to-date view of past
events which occured before we modified the interest mask.  So this
barrier also pairs with the barrier in wq_has_sleeper().

This should guarantee either ep_poll_callback or f_op->poll() (or both)
will notice the readiness of a recently-ready/modified item.

This issue was encountered by Andreas Voellmy and Junchang(Jason) Wang in:
http://thread.gmane.org/gmane.linux.kernel/1408782/

Signed-off-by: Eric Wong 
Cc: Hans Verkuil 
Cc: Jiri Olsa 
Cc: Jonathan Corbet 
Cc: Al Viro 
Cc: Davide Libenzi 
Cc: Hans de Goede 
Cc: Mauro Carvalho Chehab 
Cc: David Miller 
Cc: Eric Dumazet 
Cc: Andrew Morton 
Cc: Andreas Voellmy 
Tested-by: "Junchang(Jason) Wang" 
Cc: netdev@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

udf: don't increment lenExtents while writing to a hole

2013-01-16T01:13:21+00:00

commit fb719c59bdb4fca86ee1fd1f42ab3735ca12b6b2 upstream.

Incrementing lenExtents even while writing to a hole is bad
for performance as calls to udf_discard_prealloc and
udf_truncate_tail_extent would not return from start if
isize != lenExtents

Signed-off-by: Namjae Jeon 
Signed-off-by: Ashish Sangwan 
Signed-off-by: Jan Kara 
Signed-off-by: Ben Hutchings

nfs: fix null checking in nfs_get_option_str()

2013-01-16T01:13:19+00:00

commit e25fbe380c4e3c09afa98bcdcd9d3921443adab8 upstream.

The following null pointer check is broken.

	*option = match_strdup(args);
	return !option;

The pointer `option' must be non-null, and thus `!option' is always false.
Use `!*option' instead.

The bug was introduced in commit c5cb09b6f8 ("Cleanup: Factor out some
cut-and-paste code.").

Signed-off-by: Xi Wang 
Signed-off-by: Trond Myklebust 
Signed-off-by: Ben Hutchings

cifs: adjust sequence number downward after signing NT_CANCEL request

2013-01-16T01:13:13+00:00

commit 31efee60f489c759c341454d755a9fd13de8c03d upstream.

When a call goes out, the signing code adjusts the sequence number
upward by two to account for the request and the response. An NT_CANCEL
however doesn't get a response of its own, it just hurries the server
along to get it to respond to the original request more quickly.
Therefore, we must adjust the sequence number back down by one after
signing a NT_CANCEL request.

Reported-by: Tim Perry 
Signed-off-by: Jeff Layton 
Signed-off-by: Steve French 
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings

ext4: do not try to write superblock on ro remount w/o journal

2013-01-16T01:13:12+00:00

commit d096ad0f79a782935d2e06ae8fb235e8c5397775 upstream.

When a journal-less ext4 filesystem is mounted on a read-only block
device (blockdev --setro will do), each remount (for other, unrelated,
flags, like suid=>nosuid etc) results in a series of scary messages
from kernel telling about I/O errors on the device.

This is becauese of the following code ext4_remount():

       if (sbi->s_journal == NULL)
                ext4_commit_super(sb, 1);

at the end of remount procedure, which forces writing (flushing) of
a superblock regardless whenever it is dirty or not, if the filesystem
is readonly or not, and whenever the device itself is readonly or not.

We only need call ext4_commit_super when the file system had been
previously mounted read/write.

Thanks to Eric Sandeen for help in diagnosing this issue.

Signed-off-By: Michael Tokarev 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Ben Hutchings

jbd2: fix assertion failure in jbd2_journal_flush()

2013-01-16T01:13:11+00:00

commit d7961c7fa4d2e3c3f12be67e21ba8799b5a7238a upstream.

The following race is possible between start_this_handle() and someone
calling jbd2_journal_flush().

Process A                              Process B
start_this_handle().
  if (journal->j_barrier_count) # false
  if (!journal->j_running_transaction) { #true
    read_unlock(&journal->j_state_lock);
                                       jbd2_journal_lock_updates()
                                       jbd2_journal_flush()
                                         write_lock(&journal->j_state_lock);
                                         if (journal->j_running_transaction) {
                                           # false
                                         ... wait for committing trans ...
                                         write_unlock(&journal->j_state_lock);
    ...
    write_lock(&journal->j_state_lock);
    if (!journal->j_running_transaction) { # true
      jbd2_get_transaction(journal, new_transaction);
    write_unlock(&journal->j_state_lock);
    goto repeat; # eventually blocks on j_barrier_count > 0
                                         ...
                                         J_ASSERT(!journal->j_running_transaction);
                                           # fails

We fix the race by rechecking j_barrier_count after reacquiring j_state_lock
in exclusive mode.

Reported-by: yjwsignal@empal.com
Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Ben Hutchings

ext4: check dioread_nolock on remount

2013-01-16T01:13:11+00:00

commit 261cb20cb2f0737a247aaf08dff7eb065e3e5b66 upstream.

Currently we allow enabling dioread_nolock mount option on remount for
filesystems where blocksize < PAGE_CACHE_SIZE.  This isn't really
supported so fix the bug by moving the check for blocksize !=
PAGE_CACHE_SIZE into parse_options(). Change the original PAGE_SIZE to
PAGE_CACHE_SIZE along the way because that's what we are really
interested in.

Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Eric Sandeen 
Signed-off-by: Ben Hutchings

ext4: fix extent tree corruption caused by hole punch

2013-01-16T01:13:10+00:00

commit c36575e663e302dbaa4d16b9c72d2c9a913a9aef upstream.

When depth of extent tree is greater than 1, logical start value of
interior node is not correctly updated in ext4_ext_rm_idx.

Signed-off-by: Forrest Liu 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Ashish Sangwan 
Signed-off-by: Ben Hutchings

udf: fix memory leak while allocating blocks during write

2013-01-03T03:33:56+00:00

commit 2fb7d99d0de3fd8ae869f35ab682581d8455887a upstream.

Need to brelse the buffer_head stored in cur_epos and next_epos.

Signed-off-by: Namjae Jeon 
Signed-off-by: Ashish Sangwan 
Signed-off-by: Jan Kara 
Signed-off-by: Ben Hutchings

exec: do not leave bprm->interp on stack

2013-01-03T03:33:45+00:00

commit b66c5984017533316fd1951770302649baf1aa33 upstream.

If a series of scripts are executed, each triggering module loading via
unprintable bytes in the script header, kernel stack contents can leak
into the command line.

Normally execution of binfmt_script and binfmt_misc happens recursively.
However, when modules are enabled, and unprintable bytes exist in the
bprm->buf, execution will restart after attempting to load matching
binfmt modules.  Unfortunately, the logic in binfmt_script and
binfmt_misc does not expect to get restarted.  They leave bprm->interp
pointing to their local stack.  This means on restart bprm->interp is
left pointing into unused stack memory which can then be copied into the
userspace argv areas.

After additional study, it seems that both recursion and restart remains
the desirable way to handle exec with scripts, misc, and modules.  As
such, we need to protect the changes to interp.

This changes the logic to require allocation for any changes to the
bprm->interp.  To avoid adding a new kmalloc to every exec, the default
value is left as-is.  Only when passing through binfmt_script or
binfmt_misc does an allocation take place.

For a proof of concept, see DoTest.sh from:

   http://www.halfdog.net/Security/2012/LinuxKernelBinfmtScriptStackDataDisclosure/

Signed-off-by: Kees Cook 
Cc: halfdog 
Cc: P J P 
Cc: Alexander Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings