drm: Check user mode against overflows

The internal mode representation drm_display_mode uses signed data
types. When converting the user mode to internal representation,
check that the unsigned values don't overflow the signed datatypes.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 9ccb92fdd7b26f7d49008d564f19fa4f006ab0bb..4d9e69cb23545afcd8cf5c018d21428a7467a951 100644 (file)
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1040,10 +1040,16 @@ void drm_crtc_convert_to_umode(struct drm_mode_modeinfo *out,
  *
  * Convert a drm_mode_modeinfo into a drm_display_mode structure to return to
  * the caller.
+ *
+ * RETURNS:
+ * Zero on success, errno on failure.
  */
-void drm_crtc_convert_umode(struct drm_display_mode *out,
-                           struct drm_mode_modeinfo *in)
+int drm_crtc_convert_umode(struct drm_display_mode *out,
+                          struct drm_mode_modeinfo *in)
 {
+       if (in->clock > INT_MAX || in->vrefresh > INT_MAX)
+               return -ERANGE;
+
        out->clock = in->clock;
        out->hdisplay = in->hdisplay;
        out->hsync_start = in->hsync_start;
@@ -1060,6 +1066,8 @@ void drm_crtc_convert_umode(struct drm_display_mode *out,
        out->type = in->type;
        strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN);
        out->name[DRM_DISPLAY_MODE_LEN-1] = 0;
+
+       return 0;
 }
 
 /**
@@ -1820,7 +1828,12 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
                        goto out;
                }
 
-               drm_crtc_convert_umode(mode, &crtc_req->mode);
+               ret = drm_crtc_convert_umode(mode, &crtc_req->mode);
+               if (ret) {
+                       DRM_DEBUG_KMS("Invalid mode\n");
+                       goto out;
+               }
+
                drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
        }
 
@@ -2492,7 +2505,12 @@ int drm_mode_attachmode_ioctl(struct drm_device *dev,
                goto out;
        }
 
-       drm_crtc_convert_umode(mode, umode);
+       ret = drm_crtc_convert_umode(mode, umode);
+       if (ret) {
+               DRM_DEBUG_KMS("Invalid mode\n");
+               drm_mode_destroy(dev, mode);
+               goto out;
+       }
 
        drm_mode_attachmode(dev, connector, mode);
 out:
@@ -2535,7 +2553,12 @@ int drm_mode_detachmode_ioctl(struct drm_device *dev,
        }
        connector = obj_to_connector(obj);
 
-       drm_crtc_convert_umode(&mode, umode);
+       ret = drm_crtc_convert_umode(&mode, umode);
+       if (ret) {
+               DRM_DEBUG_KMS("Invalid mode\n");
+               goto out;
+       }
+
        ret = drm_mode_detachmode(dev, connector, &mode);
 out:
        mutex_unlock(&dev->mode_config.mutex);