[Mesa-dev] [PATCH 1/3] anv/descriptor_set: Fix binding partly undefined descriptor sets

[Nanley Chery]

Section 13.2.3. of the Vulkan spec requires that implementations be able to
bind sparsely-defined Descriptor Sets without any errors or exceptions.

When binding a descriptor set that contains a dynamic buffer binding/descriptor,
the driver attempts to dereference the descriptor's buffer_view field if it is
non-NULL. It currently segfaults on undefined descriptors as this field is never
zero-initialized. Zero undefined descriptors to avoid segfaulting. This
solution was suggested by Jason Ekstrand.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96850
Cc: 12.0 <mesa-stable at lists.freedesktop.org>
Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
---
 src/intel/vulkan/anv_descriptor_set.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/intel/vulkan/anv_descriptor_set.c b/src/intel/vulkan/anv_descriptor_set.c
index 448ae0e..f06d2e4 100644
--- a/src/intel/vulkan/anv_descriptor_set.c
+++ b/src/intel/vulkan/anv_descriptor_set.c
@@ -412,8 +412,8 @@ anv_descriptor_set_create(struct anv_device *device,
    /* Go through and fill out immutable samplers if we have any */
    struct anv_descriptor *desc = set->descriptors;
    for (uint32_t b = 0; b < layout->binding_count; b++) {
-      if (layout->binding[b].immutable_samplers) {
-         for (uint32_t i = 0; i < layout->binding[b].array_size; i++) {
+      for (uint32_t i = 0; i < layout->binding[b].array_size; i++) {
+         if (layout->binding[b].immutable_samplers) {
             /* The type will get changed to COMBINED_IMAGE_SAMPLER in
              * UpdateDescriptorSets if needed.  However, if the descriptor
              * set has an immutable sampler, UpdateDescriptorSets may never
@@ -423,6 +423,11 @@ anv_descriptor_set_create(struct anv_device *device,
                .type = VK_DESCRIPTOR_TYPE_SAMPLER,
                .sampler = layout->binding[b].immutable_samplers[i],
             };
+         } else {
+            /* By defining the descriptors to be zero now, we can later verify that
+             * the descriptor has not been populated with user data.
+             */
+            zero(desc[i]);
          }
       }
       desc += layout->binding[b].array_size;
-- 
2.9.0