From dfd51be3ca2a244bbca27a95310b60e0c14940df Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Tue, 23 Jul 2019 11:01:47 +0200
Subject: [PATCH xserver 05/15] xwayland: Do not free a NULL GBM bo
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Both `gbm_bo_create()` and `gbm_bo_create_with_modifiers()` can fail and
return `NULL`.

If that occurs, `xwl_glamor_gbm_create_pixmap()` will not create a
pixmap for the (NULL) GBM bo, but would still try to free the bo which
leads to a crash in mesa:

  [...]
  #7  <signal handler called>
  #8  in gbm_bo_destroy (bo=0x0) at ../src/gbm/main/gbm.c:439
  #9  in xwl_glamor_gbm_create_pixmap () at xwayland-glamor-gbm.c:245
  #10 in ProcCreatePixmap () at dispatch.c:1440
  #11 in Dispatch () at dispatch.c:478
  #12 in dix_main () at main.c:276

To avoid the crash, only free the GBM bo if not `NULL`.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Bugzilla: https://bugzilla.redhat.com/1729925
(cherry picked from commit d9ec525059dbe96fc893c73c0362be2a6dd73e85)
---
 hw/xwayland/xwayland-glamor-gbm.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/hw/xwayland/xwayland-glamor-gbm.c b/hw/xwayland/xwayland-glamor-gbm.c
index 80146ab6e..291e060cf 100644
--- a/hw/xwayland/xwayland-glamor-gbm.c
+++ b/hw/xwayland/xwayland-glamor-gbm.c
@@ -238,11 +238,12 @@ xwl_glamor_gbm_create_pixmap(ScreenPtr screen,
                                GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
         }
 
-        if (bo)
+        if (bo) {
             pixmap = xwl_glamor_gbm_create_pixmap_for_bo(screen, bo, depth);
 
-        if (!pixmap)
-            gbm_bo_destroy(bo);
+            if (!pixmap)
+                gbm_bo_destroy(bo);
+        }
     }
 
     if (!pixmap)
-- 
2.21.0