st/xorg: Work around cursor reference counting bugs in older X servers.

Could result in use of freed memory and consequently random crashes, e.g. on
screen resize.

3 files changed, 20 insertions, 0 deletions

diff --git a/src/gallium/state_trackers/xorg/xorg_crtc.c b/src/gallium/state_trackers/xorg/xorg_crtc.c
index daa9f8b820..5b78d57d64 100644
--- a/src/gallium/state_trackers/xorg/xorg_crtc.c
+++ b/src/gallium/state_trackers/xorg/xorg_crtc.c
@@ -276,7 +276,21 @@ err_bo_destroy:
 static void
 crtc_load_cursor_argb(xf86CrtcPtr crtc, CARD32 * image)
 {
+    xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR(crtc->scrn);
     modesettingPtr ms = modesettingPTR(crtc->scrn);
+
+    /* Older X servers have cursor reference counting bugs leading to use of
+     * freed memory and consequently random crashes. Should be fixed as of
+     * xserver 1.8, but this workaround shouldn't hurt anyway.
+     */
+    if (config->cursor)
+       config->cursor->refcnt++;
+
+    if (ms->cursor)
+       FreeCursor(ms->cursor, None);
+
+    ms->cursor = config->cursor;
+
     if (ms->screen)
 	crtc_load_cursor_argb_ga3d(crtc, image);
 #ifdef HAVE_LIBKMS
diff --git a/src/gallium/state_trackers/xorg/xorg_driver.c b/src/gallium/state_trackers/xorg/xorg_driver.c
index 372fa3d9d1..2aedbb0978 100644
--- a/src/gallium/state_trackers/xorg/xorg_driver.c
+++ b/src/gallium/state_trackers/xorg/xorg_driver.c
@@ -949,6 +949,11 @@ drv_close_screen(int scrnIndex, ScreenPtr pScreen)
 	drv_leave_vt(scrnIndex, 0);
     }
 
+    if (ms->cursor) {
+       FreeCursor(ms->cursor, None);
+       ms->cursor = NULL;
+    }
+
     if (cust && cust->winsys_screen_close)
 	cust->winsys_screen_close(cust);
 
diff --git a/src/gallium/state_trackers/xorg/xorg_tracker.h b/src/gallium/state_trackers/xorg/xorg_tracker.h
index 9de1df76aa..570368108c 100644
--- a/src/gallium/state_trackers/xorg/xorg_tracker.h
+++ b/src/gallium/state_trackers/xorg/xorg_tracker.h
@@ -98,6 +98,7 @@ typedef struct _modesettingRec
 
     Bool noAccel;
     Bool SWCursor;
+    CursorPtr cursor;
     Bool swapThrottling;
     Bool dirtyThrottling;
     CloseScreenProcPtr CloseScreen;