[patch] libertas: potential oops in debugfs

[Dan Carpenter]

If we do a zero size write then it will oops.  This can only be
triggered by root.

Reported-by: Nico Golde <nico at ngolde.de>
Reported-by: Fabian Yamaguchi <fabs at goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>

diff --git a/drivers/net/wireless/libertas/debugfs.c b/drivers/net/wireless/libertas/debugfs.c
index 668dd27..a148f14 100644
--- a/drivers/net/wireless/libertas/debugfs.c
+++ b/drivers/net/wireless/libertas/debugfs.c
@@ -913,6 +913,9 @@ static ssize_t lbs_debugfs_write(struct file *f, const char __user *buf,
 	char *p2;
 	struct debug_data *d = f->private_data;
 
+	if (cnt == 0)
+		return 0;
+
 	pdata = kmalloc(cnt, GFP_KERNEL);
 	if (pdata == NULL)
 		return 0;