dlm: check for null in device_write

If `device_write' method is called via "dlm-control",
file->private_data is NULL. (See ctl_device_open() in
user.c. ) Through proc->flags is read.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index ebbcf38..1aa76b3 100644 (file)
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -538,7 +538,7 @@ static ssize_t device_write(struct file *file, const char __user *buf,
 
        /* do we really need this? can a write happen after a close? */
        if ((kbuf->cmd == DLM_USER_LOCK || kbuf->cmd == DLM_USER_UNLOCK) &&
-           test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
+           (proc && test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags)))
                return -EINVAL;
 
        sigfillset(&allsigs);