HID: fix memory leak on error patch in debug code

Author: Julia Lawall <julia@diku.dk>

Error handling code following a kzalloc should free the allocated data.

The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// 
@r exists@
local idexpression x;
statement S;
expression E;
identifier f,f1,l;
position p1,p2;
expression *ptr != NULL;
@@

x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...x...+> }
(
x->f1 = E
|
 (x->f1 == NULL || ...)
|
 f(...,x->f1,...)
)
...>
(
 return \(0\|<+...x...+>\|ptr\);
|
 return@p2 ...;
)

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// 

Signed-off-by: Julia Lawall 
Cc: Jiri Kosina 
Signed-off-by: Andrew Morton 
Signed-off-by: Jiri Kosina 

---
 drivers/hid/hid-debug.c | 1 +
 1 file changed, 1 insertion(+)
 
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index a331a18..06e87dc 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -909,6 +909,7 @@ static int hid_debug_events_open(struct inode *inode, struct file *file)
 
 	if (!(list->hid_debug_buf = kzalloc(sizeof(char) * HID_DEBUG_BUFSIZE, GFP_KERNEL))) {
 		err = -ENOMEM;
+		kfree(list);
 		goto out;
 	}
 	list->hdev = (struct hid_device *) inode->i_private;