Messages in this thread | | | Date | Tue, 12 Aug 2014 17:27:18 -0700 | From | Stepan Moskovchenko <> | Subject | Re: [PATCH] of: Deep-copy names of platform devices |
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On 8/12/2014 9:12 AM, Kumar Gala wrote: > > On Aug 11, 2014, at 9:42 PM, Stepan Moskovchenko <stepanm@codeaurora.org> 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. >> >> 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 <stepanm@codeaurora.org> >> --- >> I suppose creating a 'pdev_set_name' API may seem like >> another possibility, but I feel that dev.name and pdev.name >> have two different meanings. One is used for device/driver >> binding purposes, whereas the other serves a more general >> identification purpose, and is used for things like sysfs. >> Drivers might want to change dev.name while leaving the >> pdev.name alone. I guess yet another possibility would be >> to prohibit calling dev_set_name() on devices created from >> device tree, but a driver does not necessarily know how a >> given platform_device was allocated. >> >> drivers/of/device.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/of/device.c b/drivers/of/device.c >> index f685e55..fe5f025 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 > > Don’t we need to free this is of_device_unregister() now? > > - k >
Argh. I was confused by the asymmetric naming of the APIs, but after digging through the callers outside from drivers/of/, it looks like things do eventually filter down to of_device_add() in all the cases I could find. So yes, this does need to be fixed. Expect v2 soon.
Thanks Steve
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