From 821c0bc89290a6dfe1b1490288810694a1e0287d Mon Sep 17 00:00:00 2001
From: Won Chung <wonchung@google.com>
Date: Mon, 18 Apr 2022 17:59:31 +0000
Subject: misc/mei: Add NULL check to component match callback functions
Git-commit: 84d4333c1e28cedfad37c5347b4a94a3565a454f
Patch-mainline: v5.19-rc1
References: jsc#PED-1218
Currently, component_match callback functions used in mei refers to the
driver name, assuming that the component device being matched has a
driver bound. It can cause a NULL pointer dereference when a device
without a driver bound registers a component. This is due to the nature
of the component framework where all registered components are matched
in any component_match callback functions. So even if a component is
registered by a totally irrelevant device, that component is also
shared to these callbacks for i915 driver.
To prevent totally irrelevant device being matched for i915 and causing
a NULL pointer dereference for checking driver name, add a NULL check on
dev->driver to check if there is a driver bound before checking the
driver name.
In the future, the string compare on the driver name, "i915" may need to
be refactored too.
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Won Chung <wonchung@google.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/misc/mei/hdcp/mei_hdcp.c | 2 +-
drivers/misc/mei/pxp/mei_pxp.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
index ec2a4fce8581..e889a8bd7ac8 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.c
+++ b/drivers/misc/mei/hdcp/mei_hdcp.c
@@ -784,7 +784,7 @@ static int mei_hdcp_component_match(struct device *dev, int subcomponent,
{
struct device *base = data;
- if (strcmp(dev->driver->name, "i915") ||
+ if (!dev->driver || strcmp(dev->driver->name, "i915") ||
subcomponent != I915_COMPONENT_HDCP)
return 0;
diff --git a/drivers/misc/mei/pxp/mei_pxp.c b/drivers/misc/mei/pxp/mei_pxp.c
index f7380d387bab..5c39457e3f53 100644
--- a/drivers/misc/mei/pxp/mei_pxp.c
+++ b/drivers/misc/mei/pxp/mei_pxp.c
@@ -131,7 +131,7 @@ static int mei_pxp_component_match(struct device *dev, int subcomponent,
{
struct device *base = data;
- if (strcmp(dev->driver->name, "i915") ||
+ if (!dev->driver || strcmp(dev->driver->name, "i915") ||
subcomponent != I915_COMPONENT_PXP)
return 0;
--
2.39.0