Re: [PATCH v3 2/2] can: gs_usb: fix DMA memory leak on close

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On Sun. 12 juin 2022 at 00:35, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote:
> On 10.06.2022 17:33:37, Rhett Aultman wrote:
> > The gs_usb driver allocates DMA memory with usb_alloc_coherent() in
> > gs_can_open() and then keeps this memory in an URB, with the expectation
> > that the memory will be freed when the URB is killed in gs_can_close().
> > Memory allocated with usb_alloc_coherent() cannot be freed in this way
> > and must be freed using usb_free_coherent() instead.  This means that
> > repeated cycles of calling gs_can_open() and gs_can_close() will lead to
> > a memory leak.
> >
> > Historically, drivers have handled this by keeping an array of pointers
> > to their DMA rx buffers and explicitly freeing them.  For an example of
> > this technique used in the esd_usb2 driver, see here:
> > https://www.spinics.net/lists/linux-can/msg08203.html

Hi Rhett,

It seems that you missed one of my previous comments. Please check this:
https://lore.kernel.org/linux-can/CAMZ6RqJ6fq=Rv-BuL6bA89E_DQdJ949quSWjyphy+2tOJJ=kGw@xxxxxxxxxxxxxx/
and add the Fixes tag.

Thank you.

> Better reference the commit or use a link to lore.kernel.org:
>
> 928150fad41b ("can: esd_usb2: fix memory leak")
> https://lore.kernel.org/all/b31b096926dcb35998ad0271aac4b51770ca7cc8.1627404470.git.paskripkin@xxxxxxxxx/
>
> Marc
>
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
> Embedded Linux                   | https://www.pengutronix.de  |
> Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |



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