Re: [PATCH] mtd: fix memory leak

[Mathias Krause]

On 30.01.2011 at 15:52, Artem Bityutskiy wrote:
> Hi,
> 
> On Sun, 2011-01-30 at 10:31 +0100, Mathias Krause wrote:
>> diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
>> index 5239328..8d28fa0 100644
>> --- a/drivers/mtd/devices/phram.c
>> +++ b/drivers/mtd/devices/phram.c
>> @@ -117,6 +117,7 @@ static void unregister_devices(void)
>> 	list_for_each_entry_safe(this, safe, &phram_list, list) {
>> 		del_mtd_device(&this->mtd);
>> 		iounmap(this->mtd.priv);
>> +		kfree(this->mtd.name);
>> 		kfree(this);
>> 	}
> 
> Since register_device() did not allocate it, unregister_devices() should
> not free it.

I agree with you, the internal API is a little quirky regarding that point. register_device() should strdup() the name and not just blindly use it. But since the memory for name was already allocated via kmalloc() in phram_setup() it seems a little nitpicky to copy it once again in register_device().

> Hence, I think it is better to free(name) just after
> calling unregister_devices().

This is not possible because unregister_devices() unregisters all devices, not just a single instance. Though name must be freed for every object in the list. After unregister_devices() returns the list is empty and no pointer to the memory locations do exist any more. So my patch was the straight forward fix for the memory leak.


Regards,
Mathias--
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