[PATCH] Fix SIGSEGV in libdrm for heigth = 0 and width = 0

[Thomas Meyer]

drm_intel_gem_bo_free() crashes because the list bo_gem->vma_list is not
yet initialised, but the error path tries to free it.

See also https://bugs.freedesktop.org/show_bug.cgi?id=75844

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Thomas Meyer <thomas at m3y3r.de>
---

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index f2f4fea..b3e9dba 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -759,15 +759,16 @@ retry:
                bo_gem->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
                bo_gem->stride = 0;

+               /* drm_intel_gem_bo_free calls DRMLISTDEL() for an uninitialized
+                  list (vma_list), so better set the list head here */
+               DRMINITLISTHEAD(&bo_gem->name_list);
+               DRMINITLISTHEAD(&bo_gem->vma_list);
                if (drm_intel_gem_bo_set_tiling_internal(&bo_gem->bo,
                                                         tiling_mode,
                                                         stride)) {
                    drm_intel_gem_bo_free(&bo_gem->bo);
                    return NULL;
                }
-
-               DRMINITLISTHEAD(&bo_gem->name_list);
-               DRMINITLISTHEAD(&bo_gem->vma_list);
        }

        bo_gem->name = name;