linux-kernel - Re: [RFC v5 07/11] [media] vb2: add in-fence support to QBUF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20171117130801.GH19033@jade>
Date:   Fri, 17 Nov 2017 11:08:01 -0200
From:   Gustavo Padovan <gustavo@...ovan.org>
To:     Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc:     Alexandre Courbot <acourbot@...omium.org>,
        linux-media@...r.kernel.org, Hans Verkuil <hverkuil@...all.nl>,
        Shuah Khan <shuahkh@....samsung.com>,
        Pawel Osciak <pawel@...iak.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Brian Starkey <brian.starkey@....com>,
        Thierry Escande <thierry.escande@...labora.com>,
        linux-kernel@...r.kernel.org,
        Gustavo Padovan <gustavo.padovan@...labora.com>
Subject: Re: [RFC v5 07/11] [media] vb2: add in-fence support to QBUF

2017-11-17 Mauro Carvalho Chehab <mchehab@....samsung.com>:

> Em Fri, 17 Nov 2017 15:49:23 +0900
> Alexandre Courbot <acourbot@...omium.org> escreveu:
> 
> > > @@ -178,6 +179,12 @@ static int vb2_queue_or_prepare_buf(struct 
> > > vb2_queue *q, struct v4l2_buffer *b,
> > >  		return -EINVAL;
> > >  	}
> > >  
> > > +	if ((b->fence_fd != 0 && b->fence_fd != -1) &&  
> > 
> > Why do we need to consider both values invalid? Can 0 ever be a valid fence 
> > fd?
> 
> Programs that don't use fences will initialize reserved2/fence_fd field
> at the uAPI call to zero.
> 
> So, I guess using fd=0 here could be a problem. Anyway, I would, instead,
> do:
> 
> 	if ((b->fence_fd < 1) &&
> 		...
> 
> as other negative values are likely invalid as well.

We are checking when the fence_fd is set but the flag wasn't. Checking
for < 1 is exactly the opposite. so we keep as is or do it fence_fd > 0.

Gustavo