linux-kernel - [PATCH AUTOSEL 4.19 216/671] platform/x86: wmi: fix potential null pointer dereference

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Date:   Thu, 16 Jan 2020 11:52:05 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mattias Jacobsson <2pi@....nu>, Darren Hart <dvhart@...radead.org>,
        Sasha Levin <sashal@...nel.org>,
        platform-driver-x86@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 216/671] platform/x86: wmi: fix potential null pointer dereference

From: Mattias Jacobsson <2pi@....nu>

[ 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@....nu>
Signed-off-by: Darren Hart (VMware) <dvhart@...radead.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/platform/x86/wmi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 04791ea5d97b..35cdc3998eb5 100644
--- 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;
 
-- 
2.20.1