linux-kernel - Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

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Date:   Tue, 15 May 2018 22:39:36 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

On Tue, May 15, 2018 at 12:29:10PM -0500, Gustavo A. R. Silva wrote:
> 
> 
> On 05/15/2018 09:16 AM, Dan Carpenter wrote:
> > > > 
> > > > I'm curious about how you finally resolved to handle these issues.
> > > > 
> > > > I noticed Smatch is no longer reporting them.
> > > 
> > > There was no direct fix for it, but maybe this patch has something
> > > to do with the smatch error report cleanup:
> > > 
> > > commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56
> > > Author: Sami Tolvanen <samitolvanen@...gle.com>
> > > Date:   Tue May 8 13:56:12 2018 -0400
> > > 
> > >      media: v4l2-ioctl: replace IOCTL_INFO_STD with stub functions
> > >      This change removes IOCTL_INFO_STD and adds stub functions where
> > >      needed using the DEFINE_V4L_STUB_FUNC macro. This fixes indirect call
> > >      mismatches with Control-Flow Integrity, caused by calling standard
> > >      ioctls using a function pointer that doesn't match the function type.
> > >      Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
> > >      Signed-off-by: Hans Verkuil <hansverk@...co.com>
> > >      Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
> > > 
> 
> Thanks, Mauro.
> 
> > 
> > Possibly...  There was an ancient bug in Smatch's function pointer
> > handling.  I just pushed a fix for it now so the warning is there on
> > linux-next.
> > 
> 
> Dan,
> 
> These are all the Spectre media issues I see smatch is reporting in
> linux-next-20180515:
> 
> drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
> warn: potential spectre issue 'pin->error_inj_args'
> drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn:
> potential spectre issue 'ca->slot_info' (local cap)
> drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
> potential spectre issue 'p->ule_next_hdr'
> 
> I pulled the latest changes from the smatch repository and compiled it.
> 
> I'm running smatch v0.5.0-4459-g2f66d40 now. Is this the latest version?
> 
> I wonder if there is anything I might be missing.
> 

You'd need to rebuild the db (possibly twice but definitely once).

regards,
dan carpenter