HID: core: Avoid uninitialized buffer access

commit 79b568b9 upstream.

hid_connect adds various strings to the buffer but they're all
conditional. You can find circumstances where nothing would be written
to it but the kernel will still print the supposedly empty buffer with
printk. This leads to corruption on the console/in the logs.

Ensure buf is initialized to an empty string.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
[dvhart: Initialize string to "" rather than assign buf[0] = NULL;]
Cc: Jiri Kosina <jikos@kernel.org>
Cc: linux-input@vger.kernel.org
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/hid/hid-core.c

@@ -1561,7 +1561,7 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
 		"Multi-Axis Controller"
 	};
 	const char *type, *bus;
-	char buf[64];
+	char buf[64] = "";
 	unsigned int i;
 	int len;
 	int ret;