Re: Commit "rsi: fix memory leak in rsi_load_ta_instructions()" breaks things

[Mike Looijmans <mike.looijmans@topic.nl>]

On 24-07-15 10:39, Alexey Khoroshilov wrote:
> Dear Mike,
>
> On 24.07.2015 14:01, Mike Looijmans wrote:
>> Regarding this commit:
>>
>> https://lkml.org/lkml/2014/12/12/709
>>
>>      rsi: fix memory leak in rsi_load_ta_instructions()
>>
>>      Memory allocated by kmemdup() in rsi_load_ta_instructions() is leaked.
>>      But duplication of firmware data here is useless,
>>      so the patch removes kmemdup() at all.
>>
>>      Found by Linux Driver Verification project (linuxtesting.org).
>>
>>      Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
>>      Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
>>
>> We use this driver for the Redpine Wifi chip on our "florida" board, and
>> after this commit it stopped working. Symptom was that the "wlan0"
>> device was not created at all. Reverting the commit makes it work again.
>>
>> Apparently, the kmemdup action is needed for something. I suspect the
>> DMA controller is still copying the firmware data before the method
>> returned.
>
> To test your hypothesis, could you please check if it is still broken
> with kfree(fw); added just after release_firmware(fw_entry); in
> rsi_load_ta_instructions().

Tried, and appears to work if i just kfree() the firmware copy. It does leave 
a bad taste though. I'd expect fw_entry->data to point to a kmalloc'd area as 
well. So it might work now just because it happens to be that the memory if 
"far enough away" and isn't being touched by anything else until the transfer 
is done. And on some other setup, it may suddenly fail unexpectedly.

I thought to move the kfree to a point where the driver unregisters, but 
apparently it doesn't have any internal hook for that (sdio_done or so).

I'd really like to see some comment from the Redpine folks on this, but since 
there hasn't been any event in the past year or so, I don't expect much.





Kind regards,

Mike Looijmans
System Expert

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