Mesa (staging/21.1): vulkan/device_select: avoid segfault on Wayland if wl_drm is unavailable

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Module: Mesa
Branch: staging/21.1
Commit: b849e317a10c9407fe0ba0507c13f800bdea612f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b849e317a10c9407fe0ba0507c13f800bdea612f

Author: Erik Kurzinger <ekurzinger at nvidia.com>
Date:   Mon May  3 08:18:03 2021 -0400

vulkan/device_select: avoid segfault on Wayland if wl_drm is unavailable

On Wayland, if the wl_drm interface is not available, for example if the
compositor is using the proprietary NVIDIA driver along with their egl-wayland
library, the device_select layer will fail to initialize. However, the failure
path will unconditionally call wl_drm_destroy even though info.wl_drm would be
NULL in that case. This can cause a segfault in libwayland-client.so.

To fix this, check if info.wl_drm is NULL before calling wl_drm_destroy. This
way, initialization will fail gracefully even if that interface is not present.

Signed-off-by: Erik Kurzinger <ekurzinger at nvidia.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Reviewed-by: Eric Engestrom <eric at engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10598>
(cherry picked from commit f4eb13dc55446794c4449386fa7f838ed061ce19)

---

 .pick_status.json                                      | 2 +-
 src/vulkan/device-select-layer/device_select_wayland.c | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 8b53ecc476b..2c47245eb7b 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -4,7 +4,7 @@
         "description": "vulkan/device_select: avoid segfault on Wayland if wl_drm is unavailable",
         "nominated": false,
         "nomination_type": null,
-        "resolution": 4,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": null
     },
diff --git a/src/vulkan/device-select-layer/device_select_wayland.c b/src/vulkan/device-select-layer/device_select_wayland.c
index 73db275a55a..161310b0292 100644
--- a/src/vulkan/device-select-layer/device_select_wayland.c
+++ b/src/vulkan/device-select-layer/device_select_wayland.c
@@ -139,7 +139,8 @@ int device_select_find_wayland_pci_default(struct device_pci_info *devices, uint
       }
    }
 
-   wl_drm_destroy(info.wl_drm);
+   if (info.wl_drm)
+      wl_drm_destroy(info.wl_drm);
    wl_registry_destroy(registry);
    wl_display_disconnect(display);
  out: