locks: fix NULL-deref in generic_delete_lease

commit 0efaa7e82f
  locks: generic_delete_lease doesn't need a file_lock at all

moves the call to fl->fl_lmops->lm_change() to a place in the
code where fl might be a non-lease lock.
When that happens, fl_lmops is NULL and an Oops ensures.

So add an extra test to restore correct functioning.

Reported-by: Linda Walsh <suse@tlinx.org>
Link: https://bugzilla.suse.com/show_bug.cgi?id=912569
Cc: stable@vger.kernel.org (v3.18)
Fixes: 0efaa7e82f
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
This commit is contained in:
NeilBrown 2015-01-13 15:17:43 +13:00 коммит произвёл Jeff Layton
Родитель 971780b701
Коммит 52d304eb4e
1 изменённых файлов: 1 добавлений и 1 удалений

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@ -1702,7 +1702,7 @@ static int generic_delete_lease(struct file *filp)
break;
}
trace_generic_delete_lease(inode, fl);
if (fl)
if (fl && IS_LEASE(fl))
error = fl->fl_lmops->lm_change(before, F_UNLCK, &dispose);
spin_unlock(&inode->i_lock);
locks_dispose_list(&dispose);