Date:   Tue, 11 Jan 2022 08:56:02 +0800
From:   Chen Yu <yu.c.chen@intel.com>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, linux-acpi@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] ACPI: pfr_telemetry: Fix info leak in pfrt_log_ioctl()
Message-ID: <20220111005602.GA987335@chenyu-desktop>
References: <20220107073407.GG22086@kili>
 <20220107134617.GA895400@chenyu-desktop>
 <20220110061713.GA1951@kadam>
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In-Reply-To: <20220110061713.GA1951@kadam>
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On Mon, Jan 10, 2022 at 09:17:13AM +0300, Dan Carpenter wrote:
> On Fri, Jan 07, 2022 at 09:46:17PM +0800, Chen Yu wrote:
> > On Fri, Jan 07, 2022 at 10:34:07AM +0300, Dan Carpenter wrote:
> > > The "data_info" struct is copied to the user.  It has a 4 byte struct
> > > hole after the last struct member so we need to memset that to avoid
> > > copying uninitialized stack data to the user.
> > > 
> > > Fixes: b0013e037a8b ("ACPI: Introduce Platform Firmware Runtime Telemetry driver")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > ---
> > > When you're adding a new driver to the kernel then please use the new
> > > driver's prefix instead of just the subsystem prefix.
> > > 
> > >  Bad: ACPI: Introduce Platform Firmware Runtime Telemetry driver
> > > Good: ACPI / pfr_telemetry: Introduce Platform Firmware Runtime Telemetry driver
> > > 
> > Thanks for pointing this out.
> > > Otherwise it's just up to me to guess what prefix you wanted.
> > > 
> > >  drivers/acpi/pfr_telemetry.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/acpi/pfr_telemetry.c b/drivers/acpi/pfr_telemetry.c
> > > index da50dd80192c..9abf350bd7a5 100644
> > > --- a/drivers/acpi/pfr_telemetry.c
> > > +++ b/drivers/acpi/pfr_telemetry.c
> > > @@ -83,6 +83,7 @@ static int get_pfrt_log_data_info(struct pfrt_log_data_info *data_info,
> > >  	union acpi_object *out_obj, in_obj, in_buf;
> > >  	int ret = -EBUSY;
> > >  
> > > +	memset(data_info, 0, sizeof(*data_info));
> > Just one minor question, how about moving above before:
> > data_info->status = out_obj->package.elements[LOG_STATUS_IDX].integer.value;
> > after the sanity check of the _DSM result?
> 
> I guess I wanted to keep all the memsets together.  I feel like if the
> data is invalid, then it's going to be a slow path and it's not worth
> optimizing that case.  If the data is invalid then a little slow down is
> the least of our concerns.
>
Ok, got it.

thanks,
Chenyu 
>