diff mbox

drm: Add integer overflow checking to transitional plane helpers

Message ID 1428096466-27622-1-git-send-email-matthew.d.roper@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Matt Roper April 3, 2015, 9:27 p.m. UTC
Add tests for destination rectangle integer overflow before calling the
driver's check function.  This will ensure that the transitional plane
helpers match the behavior of the full atomic helpers by always
returning -ERANGE for planes positioned beyond INT_MAX.

Note that the legacy SetPlane ioctl itself also includes similar tests
for integer overflow, so the only case where this check really matters
is when legacy cursor operations get routed through the universal plane
interface internally.

This issue was first noticed with i915 commit:

        commit ff42e093e9c9c17a6e1d6aab24875a36795f926e
        Author: Daniel Vetter <daniel.vetter@ffwll.ch>
        Date:   Mon Mar 2 16:35:20 2015 +0100

            Revert "drm/i915: Switch planes from transitional helpers to full
            atomic helpers"

The above revert switched us from full atomic helpers back to the
transitional helpers, and in doing so we lost the overflow checking here
for universal cursor updates.  Even though such extreme cursor positions
are unlikely to actually happen in the wild, we still don't want there
to be a change of behavior when drivers switch from transitional helpers
to full helpers.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84269
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
 drivers/gpu/drm/drm_plane_helper.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Comments

Shuang He April 3, 2015, 11:58 p.m. UTC | #1
Tested-By: Intel Graphics QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
Task id: 6130
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -2              272/272              270/272
ILK                                  302/302              302/302
SNB                                  303/303              303/303
IVB                                  338/338              338/338
BYT                 -1              287/287              286/287
HSW                                  361/361              361/361
BDW                                  308/308              308/308
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 PNV  igt@gem_tiled_pread_pwrite      FAIL(3)PASS(11)      FAIL(1)PASS(1)
 PNV  igt@gem_userptr_blits@coherency-sync      CRASH(5)PASS(8)      CRASH(1)PASS(1)
*BYT  igt@gem_exec_bad_domains@conflicting-write-domain      PASS(18)      FAIL(1)PASS(1)
Note: You need to pay more attention to line start with '*'
Daniel Vetter April 7, 2015, 6:12 a.m. UTC | #2
On Fri, Apr 03, 2015 at 02:27:46PM -0700, Matt Roper wrote:
> Add tests for destination rectangle integer overflow before calling the
> driver's check function.  This will ensure that the transitional plane
> helpers match the behavior of the full atomic helpers by always
> returning -ERANGE for planes positioned beyond INT_MAX.
> 
> Note that the legacy SetPlane ioctl itself also includes similar tests
> for integer overflow, so the only case where this check really matters
> is when legacy cursor operations get routed through the universal plane
> interface internally.
> 
> This issue was first noticed with i915 commit:
> 
>         commit ff42e093e9c9c17a6e1d6aab24875a36795f926e
>         Author: Daniel Vetter <daniel.vetter@ffwll.ch>
>         Date:   Mon Mar 2 16:35:20 2015 +0100
> 
>             Revert "drm/i915: Switch planes from transitional helpers to full
>             atomic helpers"
> 
> The above revert switched us from full atomic helpers back to the
> transitional helpers, and in doing so we lost the overflow checking here
> for universal cursor updates.  Even though such extreme cursor positions
> are unlikely to actually happen in the wild, we still don't want there
> to be a change of behavior when drivers switch from transitional helpers
> to full helpers.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84269
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>

Since this is just for the cursor ioctl ... shouldn't we instead move
these checks from drm_mode_setplane to __setplane_internal? That way other
drivers also can rely upon these guarantees when implementing universal
cursor support and we won't have a mismatch in what kind of plane
properties can sneak through to drivers.
-Daniel

> ---
>  drivers/gpu/drm/drm_plane_helper.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
> index 33807e0..1e9e105 100644
> --- a/drivers/gpu/drm/drm_plane_helper.c
> +++ b/drivers/gpu/drm/drm_plane_helper.c
> @@ -417,6 +417,20 @@ int drm_plane_helper_commit(struct drm_plane *plane,
>  	for (i = 0; i < 2; i++)
>  		crtc_funcs[i] = crtc[i] ? crtc[i]->helper_private : NULL;
>  
> +	/*
> +	 * Give drivers some help against integer overflows (and match the
> +	 * behavior of the full atomic helpers).
> +	 */
> +	if (plane_state->crtc_w > INT_MAX ||
> +	    plane_state->crtc_x > INT_MAX - (int32_t) plane_state->crtc_w ||
> +	    plane_state->crtc_h > INT_MAX ||
> +	    plane_state->crtc_y > INT_MAX - (int32_t) plane_state->crtc_h) {
> +		DRM_DEBUG_ATOMIC("Invalid CRTC coordinates %ux%u+%d+%d\n",
> +				 plane_state->crtc_w, plane_state->crtc_h,
> +				 plane_state->crtc_x, plane_state->crtc_y);
> +		return -ERANGE;
> +	}
> +
>  	if (plane_funcs->atomic_check) {
>  		ret = plane_funcs->atomic_check(plane, plane_state);
>  		if (ret)
> -- 
> 1.8.5.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
index 33807e0..1e9e105 100644
--- a/drivers/gpu/drm/drm_plane_helper.c
+++ b/drivers/gpu/drm/drm_plane_helper.c
@@ -417,6 +417,20 @@  int drm_plane_helper_commit(struct drm_plane *plane,
 	for (i = 0; i < 2; i++)
 		crtc_funcs[i] = crtc[i] ? crtc[i]->helper_private : NULL;
 
+	/*
+	 * Give drivers some help against integer overflows (and match the
+	 * behavior of the full atomic helpers).
+	 */
+	if (plane_state->crtc_w > INT_MAX ||
+	    plane_state->crtc_x > INT_MAX - (int32_t) plane_state->crtc_w ||
+	    plane_state->crtc_h > INT_MAX ||
+	    plane_state->crtc_y > INT_MAX - (int32_t) plane_state->crtc_h) {
+		DRM_DEBUG_ATOMIC("Invalid CRTC coordinates %ux%u+%d+%d\n",
+				 plane_state->crtc_w, plane_state->crtc_h,
+				 plane_state->crtc_x, plane_state->crtc_y);
+		return -ERANGE;
+	}
+
 	if (plane_funcs->atomic_check) {
 		ret = plane_funcs->atomic_check(plane, plane_state);
 		if (ret)