drm/radeon/kms: check AA resolve registers on r300

This is an important security fix because we allowed arbitrary values
to be passed to AARESOLVE_OFFSET. This also puts the right buffer address
in the register.

Signed-off-by: Marek Olšák <maraeo@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index fdf4bc6..56deae5 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -3381,6 +3381,26 @@
 	}
 	track->zb_dirty = false;
 
+	if (track->aa_dirty && track->aaresolve) {
+		if (track->aa.robj == NULL) {
+			DRM_ERROR("[drm] No buffer for AA resolve buffer %d !\n", i);
+			return -EINVAL;
+		}
+		/* I believe the format comes from colorbuffer0. */
+		size = track->aa.pitch * track->cb[0].cpp * track->maxy;
+		size += track->aa.offset;
+		if (size > radeon_bo_size(track->aa.robj)) {
+			DRM_ERROR("[drm] Buffer too small for AA resolve buffer %d "
+				  "(need %lu have %lu) !\n", i, size,
+				  radeon_bo_size(track->aa.robj));
+			DRM_ERROR("[drm] AA resolve buffer %d (%u %u %u %u)\n",
+				  i, track->aa.pitch, track->cb[0].cpp,
+				  track->aa.offset, track->maxy);
+			return -EINVAL;
+		}
+	}
+	track->aa_dirty = false;
+
 	prim_walk = (track->vap_vf_cntl >> 4) & 0x3;
 	if (track->vap_vf_cntl & (1 << 14)) {
 		nverts = track->vap_alt_nverts;
@@ -3455,6 +3475,7 @@
 	track->cb_dirty = true;
 	track->zb_dirty = true;
 	track->tex_dirty = true;
+	track->aa_dirty = true;
 
 	if (rdev->family < CHIP_R300) {
 		track->num_cb = 1;
@@ -3469,6 +3490,8 @@
 		track->num_texture = 16;
 		track->maxy = 4096;
 		track->separate_cube = 0;
+		track->aaresolve = true;
+		track->aa.robj = NULL;
 	}
 
 	for (i = 0; i < track->num_cb; i++) {