On 04/06/18 14:44, Rob Herring wrote:
On Fri, Jun 1, 2018 at 7:03 PM, Srinivas Kandagatla
<srinivas.kandagatla@xxxxxxxxxx> wrote:
Immediately after the platform_device_unregister() the device will be cleaned up.
Accessing the freed pointer immediately after that will crash the system.
Found this bug when kernel is built with CONFIG_PAGE_POISONING and testing
loading/unloading audio drivers in a loop on Qcom platforms.
Curious, does the unittest not catch this too?
Not sure!
Fix this by removing accessing the dev pointer.
Below is the carsh trace:
s/carsh/crash/
Yep.
[...]
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index c00d81dfac0b..84c5c899187b 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -529,10 +529,13 @@ arch_initcall_sync(of_platform_default_populate_init);
int of_platform_device_destroy(struct device *dev, void *data)
{
+ struct device_node *np;
+
/* Do not touch devices not populated from the device tree */
if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED))
return 0;
+ np = dev->of_node;
/* Recurse for any nodes that were treated as busses */
if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS))
device_for_each_child(dev, NULL, of_platform_device_destroy);
@@ -544,8 +547,8 @@ int of_platform_device_destroy(struct device *dev, void *data)
amba_device_unregister(to_amba_device(dev));
#endif
- of_node_clear_flag(dev->of_node, OF_POPULATED);
- of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
Just move these 2 lines to before unregister calls.
Make sense.. I will do that in v3.
thanks,
srini
+ of_node_clear_flag(np, OF_POPULATED);
+ of_node_clear_flag(np, OF_POPULATED_BUS);
return 0;
}
EXPORT_SYMBOL_GPL(of_platform_device_destroy);
--
2.16.2
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