Re: [RFT 2/7] firmware: fix checking for return values for fw_add_devm_name()

["Luis R. Rodriguez" <mcgrof@kernel.org>]

On Tue, Feb 27, 2018 at 03:29:53PM -0800, Kees Cook wrote:
> On Tue, Feb 27, 2018 at 3:20 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > fw_add_devm_name() adds device's name onto the devres for the
> > device so that prior to suspend we cache the firmware onto memory,
> > so that on resume the firmware is reliably available. We never
> > were checking for success for this call though, meaning in some
> > really rare cases we my have never setup the firmware cache for
> > a device, which could in turn make resume fail.
> >
> > This is all theoretical, no known issues have been reported.
> > This small issue has been present way since the addition of the
> > devres firmware cache names on v3.7.
> >
> > Fixes: f531f05ae9437 ("firmware loader: store firmware name into devres list")
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> > ---
> >  drivers/base/firmware_loader.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/base/firmware_loader.c b/drivers/base/firmware_loader.c
> > index 21dd31ef08ae..48932581c70c 100644
> > --- a/drivers/base/firmware_loader.c
> > +++ b/drivers/base/firmware_loader.c
> > @@ -431,6 +431,7 @@ int assign_fw(struct firmware *fw, struct device *device,
> >               unsigned int opt_flags)
> >  {
> >         struct fw_priv *fw_priv = fw->priv;
> > +       int ret;
> >
> >         mutex_lock(&fw_lock);
> >         if (!fw_priv->size || fw_state_is_aborted(fw_priv)) {
> > @@ -447,8 +448,13 @@ int assign_fw(struct firmware *fw, struct device *device,
> >          */
> >         /* don't cache firmware handled without uevent */
> >         if (device && (opt_flags & FW_OPT_UEVENT) &&
> > -           !(opt_flags & FW_OPT_NOCACHE))
> > -               fw_add_devm_name(device, fw_priv->fw_name);
> > +           !(opt_flags & FW_OPT_NOCACHE)) {
> > +               ret = fw_add_devm_name(device, fw_priv->fw_name);
> > +               if (ret && ret != 1) {
> 
> Why not if (ret < 0) ?

Could be, either way I remove this later for just (ret) after I adjust
fw_add_devm_name() to not return 1 anymore.

So its just a temporal check, I added this patch first so that this can
be merged into kernels who want the fix.

  Luis

> 
> -Kees
> 
> > +                       mutex_unlock(&fw_lock);
> > +                       return ret;
> > +               }
> > +       }
> >
> >         /*
> >          * After caching firmware image is started, let it piggyback
> > --
> > 2.16.2
> >
> 
> 
> 
> -- 
> Kees Cook
> Pixel Security
> 

-- 
Luis Rodriguez, SUSE LINUX GmbH
Maxfeldstrasse 5; D-90409 Nuernberg