[PATCH 3.18 114/183] locks: fix NULL-deref in generic_delete_lease

Greg Kroah-Hartman
2015-01-25T18:39:49Z

From: NeilBrown <neilb@suse.de>

commit 52d304eb4eaced9ad04b64ba7cd6ceb5153bbf18 upstream.

commit 0efaa7e82f02fe69c05ad28e905f31fc86e6f08e
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
Fixes: 0efaa7e82f02fe69c05ad28e905f31fc86e6f08e
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/locks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1702,7 +1702,7 @@ static int generic_delete_lease(struct f
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);