Re: [PATCH v3] fsi: Aspeed: Fix a potential double free

[Christophe JAILLET]

Le 21/02/2022 à 10:24, Joel Stanley a écrit :
> Hi Christophe,
>
> Thanks for the patch.
>
> On Sun, 9 Jan 2022 at 21:56, Christophe JAILLET
> <christophe.jaillet@xxxxxxxxxx> wrote:
> > A struct device can never be devm_alloc()'ed.
> > Here, it is embedded in "struct fsi_master", and "struct fsi_master" is
> > embedded in "struct fsi_master_aspeed".
> >
> > Since "struct device" is embedded, the data structure embedding it must be
> > released with the release function, as is already done here.
> >
> > So use kzalloc() instead of devm_kzalloc() when allocating "aspeed" and
> > update all error handling branches accordingly.
>
> This looks like a problem with the design of the fsi master structure.
> It's a common pattern to devm_alloc the platform devices as they are
> probed, the fsi masters all embed a copy of struct fsi_master, which
> as you say embeds struct device.
>
> Can we learn from other bus drivers (eg i2c?) how we should lay out
> these structures?
Hi,
I won't do it myself.

This goes beyond my knowledge and without the possibility to test it, it 
would be just some random trial and error (as I did in the first broken 
version of this patch).

CJ