Re: [PATCH v2] of: Deep-copy names of platform devices
From: Rob Herring <hidden>
Date: 2014-08-15 16:38:56
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linux-arm-msm, lkml
Adding Greg... On Tue, Aug 12, 2014 at 9:30 PM, Stepan Moskovchenko [off-list ref] wrote:
When we parse the device tree and allocate platform devices, the 'name' of the newly-created platform_device is set to point to the 'name' field of the 'struct device' embedded within the platform_device. This is dangerous, because the name of the 'struct device' is dynamically allocated. Drivers may call dev_set_name() on the device, which will free and reallocate the name of the device, leaving the 'name' of the platform_device pointing to the now-freed memory. Furthermore, if the dev_set_name() call is made from a driver's probe() function and a subsequent request results in probe deferral, the dangling 'name' reference may lead to the device being re-probed using the wrong driver.
This seems wrong. I don't think we want drivers to change their own device's name. The name is not supposed to change after registration. Rob
quoted hunk ↗ jump to hunk
To mitigate these scenarios, we use kstrdup to perform a deep copy of the device name when assigning the name of the platform_device, so that the platform_device name is unaffected by any calls to dev_set_name() that might made by drivers to rename the embedded 'struct device'. Signed-off-by: Stepan Moskovchenko <redacted> --- * v2 - swap cleanup order drivers/of/device.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/drivers/of/device.c b/drivers/of/device.c index f685e55..e9beae6 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c@@ -54,7 +54,7 @@ int of_device_add(struct platform_device *ofdev) /* name and id have to be set so that the platform bus doesn't get * confused on matching */ - ofdev->name = dev_name(&ofdev->dev); + ofdev->name = kstrdup(dev_name(&ofdev->dev), GFP_KERNEL); ofdev->id = -1; /* device_add will assume that this device is on the same node as@@ -75,6 +75,7 @@ EXPORT_SYMBOL(of_device_register); void of_device_unregister(struct platform_device *ofdev) { + kfree(ofdev->name); device_unregister(&ofdev->dev); } EXPORT_SYMBOL(of_device_unregister); --The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation