Mesa (staging/21.3): aux/primconvert: handle singular incomplete restarts

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Module: Mesa
Branch: staging/21.3
Commit: 90da2a2132103ae9fa5c79ddcd57d368613047df
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=90da2a2132103ae9fa5c79ddcd57d368613047df

Author: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Date:   Mon Nov  1 12:48:39 2021 -0400

aux/primconvert: handle singular incomplete restarts

if no restart indices are found, this draw must be discarded to avoid
crashing later on

Fixes: 583070748cb ("util/primconvert: handle rewriting of prim-restart draws with unsupported primtype")

Reviewed-by: Jesse Natalie <jenatali at microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13630>
(cherry picked from commit bc345281ab95313c2e34fffbd993bd1fbfc016be)

---

 .pick_status.json                             | 2 +-
 src/gallium/auxiliary/indices/u_primconvert.c | 7 +++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 27378833c51..a8d3aa683d4 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -58,7 +58,7 @@
         "description": "aux/primconvert: handle singular incomplete restarts",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "583070748cb103560b173b5789998302d517b587"
     },
diff --git a/src/gallium/auxiliary/indices/u_primconvert.c b/src/gallium/auxiliary/indices/u_primconvert.c
index 62956910aa8..5ce8dddfa1f 100644
--- a/src/gallium/auxiliary/indices/u_primconvert.c
+++ b/src/gallium/auxiliary/indices/u_primconvert.c
@@ -202,8 +202,11 @@ util_primconvert_draw_vbo(struct primconvert_context *pc,
                             &direct_draw_func);
          /* this should always be a direct translation */
          assert(new_draw.count == total_index_count);
-         /* step 3: allocate a temp buffer for an intermediate rewrite step */
-         rewrite_buffer = malloc(index_size * total_index_count);
+         /* step 3: allocate a temp buffer for an intermediate rewrite step
+          *         if no indices were found, this was a single incomplete restart and can be discarded
+          */
+         if (total_index_count)
+            rewrite_buffer = malloc(index_size * total_index_count);
          if (!rewrite_buffer) {
             if (src_transfer)
                pipe_buffer_unmap(pc->pipe, src_transfer);