base/platform: Safe handling for NULL platform data and resources

Some users of platform_device_add_{data,resources}() assume that
NULL data and resources will be handled specially, i.e. just ignored.

But the platform core ends up calling kmemdup(NULL, 0, ...), which
returns a non-NULL result (i.e. ZERO_SIZE_PTR), which causes drivers
to oops on a valid code, something like:

  if (platform_data)
  	stuff = platform_data->stuff;

This patch makes the platform core a bit more safe for such cases.

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index a01abf9..c794fec 100644 (file)
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -192,6 +192,9 @@ int platform_device_add_resources(struct platform_device *pdev,
 {
        struct resource *r;
 
+       if (!res)
+               return 0;
+
        r = kmemdup(res, sizeof(struct resource) * num, GFP_KERNEL);
        if (r) {
                pdev->resource = r;
@@ -215,8 +218,12 @@ EXPORT_SYMBOL_GPL(platform_device_add_resources);
 int platform_device_add_data(struct platform_device *pdev, const void *data,
                             size_t size)
 {
-       void *d = kmemdup(data, size, GFP_KERNEL);
+       void *d;
+
+       if (!data)
+               return 0;
 
+       d = kmemdup(data, size, GFP_KERNEL);
        if (d) {
                pdev->dev.platform_data = d;
                return 0;