Re: [PATCH v2] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

[Peter Malone <peter.malone@gmail.com>]

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Hi folks,

CVE-2018-6412 has been created for this. Is it possible for you to add a
note indicating the CVE number when merging the patch?

I received the CVE number after the patch was created and ack'd, which is
why I didn't include it in the commit message.



On Jan 31, 2018 10:49, "Mathieu Malaterre" <malat@debian.org> wrote:

> Hi Peter,
>
> On Wed, Jan 31, 2018 at 3:57 PM, Peter Malone <peter.malone@gmail.com>
> wrote:
> > Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in
> > sbusfb_ioctl_helper().
> >
> > 'index' is defined as an int in sbusfb_ioctl_helper().
> > We retrieve this from the user:
> > if (get_user(index, &c->index) ||
> >     __get_user(count, &c->count) ||
> >     __get_user(ured, &c->red) ||
> >     __get_user(ugreen, &c->green) ||
> >     __get_user(ublue, &c->blue))
> >        return -EFAULT;
> >
> > and then we use 'index' in the following way:
> > red = cmap->red[index + i] >> 8;
> > green = cmap->green[index + i] >> 8;
> > blue = cmap->blue[index + i] >> 8;
> >
> > This is a classic information leak vulnerability. 'index' should be
> > an unsigned int, given its usage above.
> >
> > This patch is straight-forward; it changes 'index' to unsigned int
> > in two switch-cases: FBIOGETCMAP_SPARC && FBIOPUTCMAP_SPARC.
> >
> > Signed-off-by: Peter Malone <peter.malone@gmail.com>
> > ---
>
> much better :)
>
> > v2: fixed formatting
> >
> >  drivers/video/fbdev/sbuslib.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/sbuslib.c
> b/drivers/video/fbdev/sbuslib.c
> > index af6fc97f4ba4..a436d44f1b7f 100644
> > --- a/drivers/video/fbdev/sbuslib.c
> > +++ b/drivers/video/fbdev/sbuslib.c
> > @@ -122,7 +122,7 @@ int sbusfb_ioctl_helper(unsigned long cmd, unsigned
> long arg,
> >                 unsigned char __user *ured;
> >                 unsigned char __user *ugreen;
> >                 unsigned char __user *ublue;
> > -               int index, count, i;
> > +               unsigned int index, count, i;
> >
> >                 if (get_user(index, &c->index) ||
> >                     __get_user(count, &c->count) ||
> > @@ -161,7 +161,7 @@ int sbusfb_ioctl_helper(unsigned long cmd, unsigned
> long arg,
> >                 unsigned char __user *ugreen;
> >                 unsigned char __user *ublue;
> >                 struct fb_cmap *cmap = &info->cmap;
> > -               int index, count, i;
> > +               unsigned int index, count, i;
> >                 u8 red, green, blue;
> >
> >                 if (get_user(index, &c->index) ||
> > --
> > 2.14.3
> >
>
> By just looking at the code and commit message:
>
> Acked-by: Mathieu Malaterre <malat@debian.org>
>

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