glx: guard swap-interval functions against destroyed drawables

The GLX specification says about glXDestroyPixmap:

    "The storage for the GLX pixmap will be freed when it is not current
     to any client."

So arguably, functions like glXSwapIntervalMESA can be called after
glXDestroyPixmap has been called for the currently bound GLXPixmap.
In that case, the GLXDRIDrawable no longer exists, and so we just skip
those calls.

Cc: 17.0 <[email protected]>
Reviewed-by: Marek Olšák <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>

2 files changed, 19 insertions, 3 deletions

diff --git a/src/glx/dri3_glx.c b/src/glx/dri3_glx.c
index 2d40f0ad458..42a94f9f242 100644
--- a/src/glx/dri3_glx.c
+++ b/src/glx/dri3_glx.c
@@ -564,6 +564,8 @@ dri3_destroy_screen(struct glx_screen *base)
 static int
 dri3_set_swap_interval(__GLXDRIdrawable *pdraw, int interval)
 {
+   assert(pdraw != NULL);
+
    struct dri3_drawable *priv =  (struct dri3_drawable *) pdraw;
    GLint vblank_mode = DRI_CONF_VBLANK_DEF_INTERVAL_1;
    struct dri3_screen *psc = (struct dri3_screen *) priv->base.psc;
@@ -597,6 +599,8 @@ dri3_set_swap_interval(__GLXDRIdrawable *pdraw, int interval)
 static int
 dri3_get_swap_interval(__GLXDRIdrawable *pdraw)
 {
+   assert(pdraw != NULL);
+
    struct dri3_drawable *priv =  (struct dri3_drawable *) pdraw;
 
   return priv->swap_interval;
diff --git a/src/glx/glxcmds.c b/src/glx/glxcmds.c
index 6c7bbfd5d1c..53c9f9ce2af 100644
--- a/src/glx/glxcmds.c
+++ b/src/glx/glxcmds.c
@@ -1761,7 +1761,11 @@ __glXSwapIntervalSGI(int interval)
           psc->driScreen->setSwapInterval) {
       __GLXDRIdrawable *pdraw =
 	 GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable);
-      psc->driScreen->setSwapInterval(pdraw, interval);
+      /* Simply ignore the command if the GLX drawable has been destroyed but
+       * the context is still bound.
+       */
+      if (pdraw)
+         psc->driScreen->setSwapInterval(pdraw, interval);
       return 0;
    }
 #endif
@@ -1807,7 +1811,14 @@ __glXSwapIntervalMESA(unsigned int interval)
       if (psc && psc->driScreen && psc->driScreen->setSwapInterval) {
          __GLXDRIdrawable *pdraw =
 	    GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable);
-	 return psc->driScreen->setSwapInterval(pdraw, interval);
+
+         /* Simply ignore the command if the GLX drawable has been destroyed but
+          * the context is still bound.
+          */
+         if (!pdraw)
+            return 0;
+
+         return psc->driScreen->setSwapInterval(pdraw, interval);
       }
    }
 #endif
@@ -1829,7 +1840,8 @@ __glXGetSwapIntervalMESA(void)
       if (psc && psc->driScreen && psc->driScreen->getSwapInterval) {
          __GLXDRIdrawable *pdraw =
 	    GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable);
-	 return psc->driScreen->getSwapInterval(pdraw);
+         if (pdraw)
+            return psc->driScreen->getSwapInterval(pdraw);
       }
    }
 #endif