[PATCH v4 09/13] locks: don't reference original flock struct in F_GETLK handlers

[Jeff Layton <jlayton@redhat.com>]

The locks code currently sanity checks the type values in the flock
struct before doing the flock->file_lock conversion. That will be
problematic when new l_type values are introduced in a later patch.

Instead, do the flock_to_posix_lock conversion first, and then sanity
check the values in the file_lock instead.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/locks.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 820322d..8180141 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1905,14 +1905,15 @@ int fcntl_getlk(struct file *filp, struct flock __user *l)
 	error = -EFAULT;
 	if (copy_from_user(&flock, l, sizeof(flock)))
 		goto out;
-	error = -EINVAL;
-	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
-		goto out;
 
 	error = flock_to_posix_lock(filp, &file_lock, &flock);
 	if (error)
 		goto out;
 
+	error = -EINVAL;
+	if ((file_lock.fl_type != F_RDLCK) && (file_lock.fl_type != F_WRLCK))
+		goto out;
+
 	error = vfs_test_lock(filp, &file_lock);
 	if (error)
 		goto out;
@@ -2073,14 +2074,15 @@ int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
 	error = -EFAULT;
 	if (copy_from_user(&flock, l, sizeof(flock)))
 		goto out;
-	error = -EINVAL;
-	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
-		goto out;
 
 	error = flock64_to_posix_lock(filp, &file_lock, &flock);
 	if (error)
 		goto out;
 
+	error = -EINVAL;
+	if ((file_lock.fl_type != F_RDLCK) && (file_lock.fl_type != F_WRLCK))
+		goto out;
+
 	error = vfs_test_lock(filp, &file_lock);
 	if (error)
 		goto out;
-- 
1.8.4.2