[PATCH] driver core: platform: use the correct callback type for bus_find_device

From: Sami Tolvanen <samitolvanen@google.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH] driver core: platform: use the correct callback type for bus_find_device
Date: Tue, 12 Nov 2019 13:41:56 -0800	[thread overview]
Message-ID: <20191112214156.3430-1-samitolvanen@google.com> (raw)

platform_find_device_by_driver calls bus_find_device and passes
platform_match as the callback function. Casting the function to a
mismatching type trips indirect call Control-Flow Integrity (CFI) checking.

This change adds a callback function with the correct type and instead
of casting the function, explicitly casts the second parameter to struct
device_driver* as expected by platform_match.

Fixes: 36f3313d6bff9 ("platform: Add platform_find_device_by_driver() helper")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 drivers/base/platform.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index b230beb6ccb4..3c0cd20925b7 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1278,6 +1278,11 @@ struct bus_type platform_bus_type = {
 };
 EXPORT_SYMBOL_GPL(platform_bus_type);
 
+static inline int __platform_match(struct device *dev, const void *drv)
+{
+	return platform_match(dev, (struct device_driver *)drv);
+}
+
 /**
  * platform_find_device_by_driver - Find a platform device with a given
  * driver.
@@ -1288,7 +1293,7 @@ struct device *platform_find_device_by_driver(struct device *start,
 					      const struct device_driver *drv)
 {
 	return bus_find_device(&platform_bus_type, start, drv,
-			       (void *)platform_match);
+			       __platform_match);
 }
 EXPORT_SYMBOL_GPL(platform_find_device_by_driver);
 

base-commit: 100d46bd72ec689a5582c2f5f4deadc5bcb92d60
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog

