linux-kernel - Re: [PATCH 2/5] platform/x86: wmi: Check if event data is not NULL

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Message-ID: <1fb172ff-b085-185e-90ea-1cd131f42b84@linux.intel.com>
Date: Mon, 19 Feb 2024 13:57:01 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Armin Wolf <W_Armin@....de>
cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
    corentin.chary@...il.com, luke@...nes.dev, 
    Hans de Goede <hdegoede@...hat.com>, platform-driver-x86@...r.kernel.org, 
    LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] platform/x86: wmi: Check if event data is not NULL

On Thu, 15 Feb 2024, Armin Wolf wrote:

> Am 15.02.24 um 13:31 schrieb Ilpo Järvinen:
> 
> > On Wed, 14 Feb 2024, Armin Wolf wrote:
> > 
> > > WMI event drivers which do not have no_notify_data set expect
> > > that each WMI event contains valid data. Evaluating _WED however
> > > might return no data, which can cause issues with such drivers.
> > > 
> > > Fix this by validating that evaluating _WED did return data.
> > > 
> > > Signed-off-by: Armin Wolf <W_Armin@....de>
> > > ---
> > >   drivers/platform/x86/wmi.c | 11 +++++++++--
> > >   1 file changed, 9 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> > > index 34d8f55afaad..8a916887c546 100644
> > > --- a/drivers/platform/x86/wmi.c
> > > +++ b/drivers/platform/x86/wmi.c
> > > @@ -1211,6 +1211,7 @@ static void wmi_notify_driver(struct wmi_block
> > > *wblock)
> > >   {
> > >   	struct wmi_driver *driver = drv_to_wdrv(wblock->dev.dev.driver);
> > >   	struct acpi_buffer data = { ACPI_ALLOCATE_BUFFER, NULL };
> > > +	union acpi_object *obj = NULL;
> > >   	acpi_status status;
> > > 
> > >   	if (!driver->no_notify_data) {
> > > @@ -1219,12 +1220,18 @@ static void wmi_notify_driver(struct wmi_block
> > > *wblock)
> > >   			dev_warn(&wblock->dev.dev, "Failed to get event
> > > data\n");
> > >   			return;
> > >   		}
> > > +
> > > +		obj = data.pointer;
> > > +		if (!obj) {
> > > +			dev_warn(&wblock->dev.dev, "Event contains not event
> > > data\n");
> > > +			return;
> > > +		}
> > >   	}
> > > 
> > >   	if (driver->notify)
> > > -		driver->notify(&wblock->dev, data.pointer);
> > > +		driver->notify(&wblock->dev, obj);
> > > 
> > > -	kfree(data.pointer);
> > > +	kfree(obj);
> > Hi Armin,
> > 
> > While looking into this patch, I failed to connect the mention of
> > no_notify_data in the commit message with the code change that does
> > nothing differently based no_notify_data being set or not, AFAICT.
> > 
> > It could be just that you need to explain things better in the commit
> > message, I'm not sure.
> 
> Here the _WED ACPI control method is only evaluated if driver->no_notify_data
> is not set.
> So the returned ACPI object should only be validated in this case, as we pass
> NULL otherwise.

Yes, I'm sorry, it seems fine. For some reason I was very confused while 
reviewing even if no_notify_data was mentioned right in the previous 
context (maybe Iused some older version of the code while trying to figure 
things out, I dunno).

-- 
 i.