Bluetooth: btbcm: Fix NULL deref in btbcm_get_board_name()

devm_kstrdup() can return a NULL pointer on failure,but this
returned value in btbcm_get_board_name() is not checked.
Add NULL check in btbcm_get_board_name(), to handle kernel NULL
pointer dereference error.

Fixes: f9183ea ("Bluetooth: btbcm: Use devm_kstrdup()")
Signed-off-by: Charles Han <hanchunchao@inspur.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Author: Charles Han

drivers/bluetooth/btbcm.c

@@ -553,6 +553,9 @@ static const char *btbcm_get_board_name(struct device *dev)
 
 	/* get rid of any '/' in the compatible string */
 	board_type = devm_kstrdup(dev, tmp, GFP_KERNEL);
+	if (!board_type)
+		return NULL;
+
 	strreplace(board_type, '/', '-');
 
 	return board_type;