linux-kernel - [PATCH 4.19 232/639] platform/x86: wmi: fix potential null pointer dereference

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Message-Id: <20200124093115.912225311@linuxfoundation.org>
Date:   Fri, 24 Jan 2020 10:26:42 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mattias Jacobsson <2pi@....nu>,
        "Darren Hart (VMware)" <dvhart@...radead.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 232/639] 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 04791ea5d97b6..35cdc3998eb59 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