2019-01-18 12:22:36

by Gerd Hoffmann

Subject: [PATCH v3 23/23] drm/qxl: add overflow checks to qxl_mode_dumb_create()

Signed-off-by: Gerd Hoffmann <[email protected]>
---
drivers/gpu/drm/qxl/qxl_dumb.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_dumb.c b/drivers/gpu/drm/qxl/qxl_dumb.c
index 272d19b677..bed6d06ee4 100644
--- a/drivers/gpu/drm/qxl/qxl_dumb.c
+++ b/drivers/gpu/drm/qxl/qxl_dumb.c
@@ -37,11 +37,13 @@ int qxl_mode_dumb_create(struct drm_file *file_priv,
uint32_t handle;
int r;
struct qxl_surface surf;
- uint32_t pitch, format;
+ uint32_t pitch, size, format;

- pitch = args->width * ((args->bpp + 1) / 8);
- args->size = pitch * args->height;
- args->size = ALIGN(args->size, PAGE_SIZE);
+ if (check_mul_overflow(args->width, ((args->bpp + 1) / 8), &pitch))
+ return -EINVAL;
+ if (check_mul_overflow(pitch, args->height, &size))
+ return -EINVAL;
+ args->size = ALIGN(size, PAGE_SIZE);

switch (args->bpp) {
case 16:
--
2.9.3

2019-01-18 15:52:45

by Daniel Vetter

Subject: Re: [PATCH v3 23/23] drm/qxl: add overflow checks to qxl_mode_dumb_create()

On Fri, Jan 18, 2019 at 01:20:20PM +0100, Gerd Hoffmann wrote:
> Signed-off-by: Gerd Hoffmann <[email protected]>

We already do all reasonable overflow checks in drm_mode_create_dumb(). If
you don't trust them I think would be better time spent typing an igt to
test this than adding redundant check in all drivers.

You're also missing one check for bpp underflows :-)
-Daniel

> ---
> drivers/gpu/drm/qxl/qxl_dumb.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/qxl/qxl_dumb.c b/drivers/gpu/drm/qxl/qxl_dumb.c
> index 272d19b677..bed6d06ee4 100644
> --- a/drivers/gpu/drm/qxl/qxl_dumb.c
> +++ b/drivers/gpu/drm/qxl/qxl_dumb.c
> @@ -37,11 +37,13 @@ int qxl_mode_dumb_create(struct drm_file *file_priv,
> uint32_t handle;
> int r;
> struct qxl_surface surf;
> - uint32_t pitch, format;
> + uint32_t pitch, size, format;
>
> - pitch = args->width * ((args->bpp + 1) / 8);
> - args->size = pitch * args->height;
> - args->size = ALIGN(args->size, PAGE_SIZE);
> + if (check_mul_overflow(args->width, ((args->bpp + 1) / 8), &pitch))
> + return -EINVAL;
> + if (check_mul_overflow(pitch, args->height, &size))
> + return -EINVAL;
> + args->size = ALIGN(size, PAGE_SIZE);
>
> switch (args->bpp) {
> case 16:
> --
> 2.9.3
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

2019-01-18 16:34:58

by Ville Syrjälä

Subject: Re: [PATCH v3 23/23] drm/qxl: add overflow checks to qxl_mode_dumb_create()

On Fri, Jan 18, 2019 at 04:49:44PM +0100, Daniel Vetter wrote:
> On Fri, Jan 18, 2019 at 01:20:20PM +0100, Gerd Hoffmann wrote:
> > Signed-off-by: Gerd Hoffmann <[email protected]>
>
> We already do all reasonable overflow checks in drm_mode_create_dumb(). If
> you don't trust them I think would be better time spent typing an igt to
> test this than adding redundant check in all drivers.
>
> You're also missing one check for bpp underflows :-)

BTW I just noticed that we don't seem to validating
create_dumb->flags at all. Someone should probably add some
checks for that, or mark it as deprecated in case we already
lost the battle with userspace stack garbage.

> -Daniel
>
> > ---
> > drivers/gpu/drm/qxl/qxl_dumb.c | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/qxl/qxl_dumb.c b/drivers/gpu/drm/qxl/qxl_dumb.c
> > index 272d19b677..bed6d06ee4 100644
> > --- a/drivers/gpu/drm/qxl/qxl_dumb.c
> > +++ b/drivers/gpu/drm/qxl/qxl_dumb.c
> > @@ -37,11 +37,13 @@ int qxl_mode_dumb_create(struct drm_file *file_priv,
> > uint32_t handle;
> > int r;
> > struct qxl_surface surf;
> > - uint32_t pitch, format;
> > + uint32_t pitch, size, format;
> >
> > - pitch = args->width * ((args->bpp + 1) / 8);
> > - args->size = pitch * args->height;
> > - args->size = ALIGN(args->size, PAGE_SIZE);
> > + if (check_mul_overflow(args->width, ((args->bpp + 1) / 8), &pitch))
> > + return -EINVAL;
> > + if (check_mul_overflow(pitch, args->height, &size))
> > + return -EINVAL;
> > + args->size = ALIGN(size, PAGE_SIZE);
> >
> > switch (args->bpp) {
> > case 16:
> > --
> > 2.9.3
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Ville Syrj?l?
Intel

2019-01-18 17:23:59

by Daniel Vetter

Subject: Re: [PATCH v3 23/23] drm/qxl: add overflow checks to qxl_mode_dumb_create()

On Fri, Jan 18, 2019 at 5:32 PM Ville Syrjälä
<[email protected]> wrote:
>
> On Fri, Jan 18, 2019 at 04:49:44PM +0100, Daniel Vetter wrote:
> > On Fri, Jan 18, 2019 at 01:20:20PM +0100, Gerd Hoffmann wrote:
> > > Signed-off-by: Gerd Hoffmann <[email protected]>
> >
> > We already do all reasonable overflow checks in drm_mode_create_dumb(). If
> > you don't trust them I think would be better time spent typing an igt to
> > test this than adding redundant check in all drivers.
> >
> > You're also missing one check for bpp underflows :-)
>
> BTW I just noticed that we don't seem to validating
> create_dumb->flags at all. Someone should probably add some
> checks for that, or mark it as deprecated in case we already
> lost the battle with userspace stack garbage.

Given that every kms client/compositor under the sun uses this (or
well, all the generic ones at least) I think we can safely assume to
have lost that battle :-/
-Daniel

>
> > -Daniel
> >
> > > ---
> > > drivers/gpu/drm/qxl/qxl_dumb.c | 10 ++++++----
> > > 1 file changed, 6 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/qxl/qxl_dumb.c b/drivers/gpu/drm/qxl/qxl_dumb.c
> > > index 272d19b677..bed6d06ee4 100644
> > > --- a/drivers/gpu/drm/qxl/qxl_dumb.c
> > > +++ b/drivers/gpu/drm/qxl/qxl_dumb.c
> > > @@ -37,11 +37,13 @@ int qxl_mode_dumb_create(struct drm_file *file_priv,
> > > uint32_t handle;
> > > int r;
> > > struct qxl_surface surf;
> > > - uint32_t pitch, format;
> > > + uint32_t pitch, size, format;
> > >
> > > - pitch = args->width * ((args->bpp + 1) / 8);
> > > - args->size = pitch * args->height;
> > > - args->size = ALIGN(args->size, PAGE_SIZE);
> > > + if (check_mul_overflow(args->width, ((args->bpp + 1) / 8), &pitch))
> > > + return -EINVAL;
> > > + if (check_mul_overflow(pitch, args->height, &size))
> > > + return -EINVAL;
> > > + args->size = ALIGN(size, PAGE_SIZE);
> > >
> > > switch (args->bpp) {
> > > case 16:
> > > --
> > > 2.9.3
> > >
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> > _______________________________________________
> > dri-devel mailing list
> > [email protected]
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Ville Syrjälä
> Intel
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel



--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch