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

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Date:   Thu, 26 Apr 2018 20:42:41 -0300
From:   Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Thu, 26 Apr 2018 16:41:56 -0500
"Gustavo A. R. Silva" <gustavo@...eddedor.com> escreveu:

> Hi Mauro,
> 
> On 04/23/2018 02:17 PM, Mauro Carvalho Chehab wrote:
> > Em Mon, 23 Apr 2018 14:11:02 -0500
> > 
> > Thanks, I 'll mark this series as rejected at patchwork.linuxtv.org.
> > Please feel free to resubmit any patch if they represent a real
> > threat, adding a corresponding description about the threat scenario
> > at the body of the e-mail.
> > 
> >> Sorry for the noise and thanks for the feedback.
> > 
> > Anytime.
> > 
> 
> I noticed you changed the status of this series from rejected to new.

Yes.

> Also, there are other similar issues in media/pci/

Well, the issues will be there everywhere on all media drivers.

I marked your patches because I need to study it carefully, after
Peter's explanations. My plan is to do it next week. Still not
sure if the approach you took is the best one or not.

As I said, one possibility is to change the way v4l2-core handles 
VIDIOC_ENUM_foo ioctls, but that would be make harder to -stable
backports.

I need a weekend to sleep on it.

> 
> I can write proper patches for all of them if you agree those are not 
> False Positives:
> 
> diff --git a/drivers/media/pci/cx18/cx18-ioctl.c 
> b/drivers/media/pci/cx18/cx18-ioctl.c
> index 80b902b..63f4388 100644
> --- a/drivers/media/pci/cx18/cx18-ioctl.c
> +++ b/drivers/media/pci/cx18/cx18-ioctl.c
> @@ -36,6 +36,8 @@
>   #include <media/tveeprom.h>
>   #include <media/v4l2-event.h>
> 
> +#include <linux/nospec.h>
> +
>   u16 cx18_service2vbi(int type)
>   {
>          switch (type) {
> @@ -488,8 +490,9 @@ static int cx18_enum_fmt_vid_cap(struct file *file, 
> void *fh,
>                  },
>          };
> 
> -       if (fmt->index > ARRAY_SIZE(formats) - 1)
> +       if (fmt->index >= ARRAY_SIZE(formats))
>                  return -EINVAL;
> +       fmt->index = array_index_nospec(fmt->index, ARRAY_SIZE(formats));
>          *fmt = formats[fmt->index];
>          return 0;
>   }
> diff --git a/drivers/media/pci/saa7134/saa7134-video.c 
> b/drivers/media/pci/saa7134/saa7134-video.c
> index 1a50ec9..d93cf09 100644
> --- a/drivers/media/pci/saa7134/saa7134-video.c
> +++ b/drivers/media/pci/saa7134/saa7134-video.c
> @@ -30,6 +30,8 @@
>   #include <media/v4l2-event.h>
>   #include <media/i2c/saa6588.h>
> 
> +#include <linux/nospec.h>
> +
>   /* ------------------------------------------------------------------ */
> 
>   unsigned int video_debug;
> @@ -1819,6 +1821,8 @@ static int saa7134_enum_fmt_vid_cap(struct file 
> *file, void  *priv,
>          if (f->index >= FORMATS)
>                  return -EINVAL;
> 
> +       f->index = array_index_nospec(f->index, FORMATS);
> +
>          strlcpy(f->description, formats[f->index].name,
>                  sizeof(f->description));
> 
> diff --git a/drivers/media/pci/tw68/tw68-video.c 
> b/drivers/media/pci/tw68/tw68-video.c
> index 8c1f4a0..a6cfb4b 100644
> --- a/drivers/media/pci/tw68/tw68-video.c
>   #include <media/v4l2-event.h>
>   #include <media/videobuf2-dma-sg.h>
> 
> +#include <linux/nospec.h>
> +
>   #include "tw68.h"
>   #include "tw68-reg.h"
> 
> @@ -789,6 +791,8 @@ static int tw68_enum_fmt_vid_cap(struct file *file, 
> void  *priv,
>          if (f->index >= FORMATS)
>                  return -EINVAL;
> 
> +       f->index = array_index_nospec(f->index, FORMATS);
> +
>          strlcpy(f->description, formats[f->index].name,
>                  sizeof(f->description));
> 
> diff --git a/drivers/media/pci/tw686x/tw686x-video.c 
> b/drivers/media/pci/tw686x/tw686x-video.c
> index c3fafa9..281d722 100644
> --- a/drivers/media/pci/tw686x/tw686x-video.c
> +++ b/drivers/media/pci/tw686x/tw686x-video.c
> @@ -25,6 +25,8 @@
>   #include "tw686x.h"
>   #include "tw686x-regs.h"
> 
> +#include <linux/nospec.h>
> +
>   #define TW686X_INPUTS_PER_CH           4
>   #define TW686X_VIDEO_WIDTH             720
>   #define TW686X_VIDEO_HEIGHT(id)                ((id & V4L2_STD_525_60) 
> ? 480 : 576)
> @@ -981,6 +983,7 @@ static int tw686x_enum_fmt_vid_cap(struct file 
> *file, void *priv,
>   {
>          if (f->index >= ARRAY_SIZE(formats))
>                  return -EINVAL;
> +       f->index = array_index_nospec(f->index, ARRAY_SIZE(formats));
>          f->pixelformat = formats[f->index].fourcc;
>          return 0;
>   }
> 
> 
> Thanks
> --
> Gustavo



Thanks,
Mauro