platform/x86: wmi: fix potential null pointer dereference

[ Upstream commit c355ec651a8941864549f2586f969d0eb7bf499a ]

In the function wmi_dev_match() the variable id is dereferenced without
first performing a NULL check. The variable can for example be NULL if
a WMI driver is registered without specifying the id_table field in
struct wmi_driver.

Add a NULL check and return that the driver can't handle the device if
the variable is NULL.

Fixes: 844af950da94 ("platform/x86: wmi: Turn WMI into a bus driver")
Signed-off-by: Mattias Jacobsson <2pi@mok.nu>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 04791ea..35cdc39 100644 (file)
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -768,6 +768,9 @@ static int wmi_dev_match(struct device *dev, struct device_driver *driver)
        struct wmi_block *wblock = dev_to_wblock(dev);
        const struct wmi_device_id *id = wmi_driver->id_table;
 
+       if (id == NULL)
+               return 0;
+
        while (id->guid_string) {
                uuid_le driver_guid;