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

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

[Mike Looijmans]

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.

Having no experience with this part of the kernel, I wasn't able to come up 
with a more constructive solution than just reverting the patch.

Kind regards,
Mike Looijmans.


Kind regards,

Mike Looijmans
System Expert

TOPIC Embedded Products
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
Telefax: +31 (0) 499 33 69 70
E-mail: mike.looijmans@topicproducts.com
Website: www.topicproducts.com

Please consider the environment before printing this e-mail

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

[Kalle Valo]

Mike Looijmans <mike.looijmans@topic.nl> writes:

> 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.
>
> Having no experience with this part of the kernel, I wasn't able to
> come up with a more constructive solution than just reverting the
> patch.

Hmm, rsi doesn't seem to have an entry in MAINTAINERS? Do we have a
maintainer for this driver? Adding Fariya as the first rsi commiter.

Unless someone has better suggestions I'll just revert the patch.

-- 
Kalle Valo

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

[Alexey Khoroshilov]

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().

--
Thanks,
Alexey

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

[Mike Looijmans]

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

TOPIC Embedded Products
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
Telefax: +31 (0) 499 33 69 70
E-mail: mike.looijmans@topicproducts.com
Website: www.topicproducts.com

Please consider the environment before printing this e-mail

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

[Alexey Khoroshilov]

On 24.07.2015 18:02, Mike Looijmans wrote:
> 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.

May be if firmware comes from userspace it is mapped to both kernel and
userspace and by some reason it is not good for DMA.
Another idea is fw_entry->data appears to be misaligned somehow.

--
Alexey

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

[Mike Looijmans]

On 24-07-15 13:35, Alexey Khoroshilov wrote:
> On 24.07.2015 18:02, Mike Looijmans wrote:
>> 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.
>
> May be if firmware comes from userspace it is mapped to both kernel and
> userspace and by some reason it is not good for DMA.
> Another idea is fw_entry->data appears to be misaligned somehow.

Just read some documentation:
https://kernel.org/doc/Documentation/firmware_class/README
It states "kernel: grows a buffer in PAGE_SIZE increments to hold the image as 
it comes in". Probably the firmware buffer is fragmented in memory as a 
result, and that wouldn't be very DMA friendly indeed. The copy would be 
contiguous again.

I noticed that the same kfree is missing in the usb glue part of the RSI 
driver. I can't test that though, we only have the SDIO connected.

I can submit a patch to add the "kfree()" call. Don't know about the revert 
though, can I just submit the revert as a patch and then the "kfree" as a 
second patch in the same set?

Mike.



Kind regards,

Mike Looijmans
System Expert

TOPIC Embedded Products
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
Telefax: +31 (0) 499 33 69 70
E-mail: mike.looijmans@topicproducts.com
Website: www.topicproducts.com

Please consider the environment before printing this e-mail

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

[Kalle Valo]

Mike Looijmans <mike.looijmans@topic.nl> writes:

> On 24-07-15 13:35, Alexey Khoroshilov wrote:
>> On 24.07.2015 18:02, Mike Looijmans wrote:
>>> 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.
>>
>> May be if firmware comes from userspace it is mapped to both kernel and
>> userspace and by some reason it is not good for DMA.
>> Another idea is fw_entry->data appears to be misaligned somehow.
>
> Just read some documentation:
> https://kernel.org/doc/Documentation/firmware_class/README
> It states "kernel: grows a buffer in PAGE_SIZE increments to hold the
> image as it comes in". Probably the firmware buffer is fragmented in
> memory as a result, and that wouldn't be very DMA friendly indeed. The
> copy would be contiguous again.
>
> I noticed that the same kfree is missing in the usb glue part of the
> RSI driver. I can't test that though, we only have the SDIO connected.
>
> I can submit a patch to add the "kfree()" call. Don't know about the
> revert though, can I just submit the revert as a patch and then the
> "kfree" as a second patch in the same set?

Better to do the revert and kfree() addition in one patch, they are
simple enough. Just document in the commit log that it reverts the
broken commit.

And remember to add CC stable to the commit log so that the fix goes to
stable releases.

-- 
Kalle Valo

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

[Alexey Khoroshilov]

On 24.07.2015 21:12, Kalle Valo wrote:
> Mike Looijmans <mike.looijmans@topic.nl> writes:
> 
>> On 24-07-15 13:35, Alexey Khoroshilov wrote:
>>> On 24.07.2015 18:02, Mike Looijmans wrote:
>>>> 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.
>>>
>>> May be if firmware comes from userspace it is mapped to both kernel and
>>> userspace and by some reason it is not good for DMA.
>>> Another idea is fw_entry->data appears to be misaligned somehow.
>>
>> Just read some documentation:
>> https://kernel.org/doc/Documentation/firmware_class/README
>> It states "kernel: grows a buffer in PAGE_SIZE increments to hold the
>> image as it comes in". Probably the firmware buffer is fragmented in
>> memory as a result, and that wouldn't be very DMA friendly indeed. The
>> copy would be contiguous again.

Interesting idea. Even fw_get_filesystem_firmware() uses vmalloc(), so
fw_entry->data may be physically noncontiguous in case of reading
firmware from file system as well.

The only my doubt is whether contiguous memory is required here. As far
as I can see, rsi_copy_to_card() writes data by blocks of size
dev->tx_blk_size that is 256 for rsi_91x_sdio. So, it is not clear where
problems can appear.


>> I noticed that the same kfree is missing in the usb glue part of the
>> RSI driver. I can't test that though, we only have the SDIO connected.
>>
>> I can submit a patch to add the "kfree()" call. Don't know about the
>> revert though, can I just submit the revert as a patch and then the
>> "kfree" as a second patch in the same set?
> 
> Better to do the revert and kfree() addition in one patch, they are
> simple enough. Just document in the commit log that it reverts the
> broken commit.
> 
> And remember to add CC stable to the commit log so that the fix goes to
> stable releases.

Agree with Kalle with a couple of notes.

To document a fix of a broken commit the preferable way is to use Fixes:
tag.
https://kernel.org/doc/Documentation/SubmittingPatches

Also it would be useful to add a comment before kmemdup() with
information why it is needed there.

--
Alexey

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

[Kalle Valo]

Alexey Khoroshilov <khoroshilov@ispras.ru> writes:

> On 24.07.2015 21:12, Kalle Valo wrote:
>> Mike Looijmans <mike.looijmans@topic.nl> writes:
>> 

>>> Just read some documentation:
>>> https://kernel.org/doc/Documentation/firmware_class/README
>>> It states "kernel: grows a buffer in PAGE_SIZE increments to hold the
>>> image as it comes in". Probably the firmware buffer is fragmented in
>>> memory as a result, and that wouldn't be very DMA friendly indeed. The
>>> copy would be contiguous again.
>
> Interesting idea. Even fw_get_filesystem_firmware() uses vmalloc(), so
> fw_entry->data may be physically noncontiguous in case of reading
> firmware from file system as well.
>
> The only my doubt is whether contiguous memory is required here. As far
> as I can see, rsi_copy_to_card() writes data by blocks of size
> dev->tx_blk_size that is 256 for rsi_91x_sdio. So, it is not clear where
> problems can appear.

You cannot DMA from memory allocated with vmalloc(). So kmalloc() & co
has to be used when doing DMA.

>>> I can submit a patch to add the "kfree()" call. Don't know about the
>>> revert though, can I just submit the revert as a patch and then the
>>> "kfree" as a second patch in the same set?
>> 
>> Better to do the revert and kfree() addition in one patch, they are
>> simple enough. Just document in the commit log that it reverts the
>> broken commit.
>> 
>> And remember to add CC stable to the commit log so that the fix goes to
>> stable releases.
>
> Agree with Kalle with a couple of notes.
>
> To document a fix of a broken commit the preferable way is to use Fixes:
> tag.
> https://kernel.org/doc/Documentation/SubmittingPatches
>
> Also it would be useful to add a comment before kmemdup() with
> information why it is needed there.

Good points.

-- 
Kalle Valo