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authorEric Anholt <[email protected]>2018-03-20 10:42:12 -0700
committerEric Anholt <[email protected]>2018-03-26 17:33:37 -0700
commit0356db022da819176d9d0eacab63d4c2c852f876 (patch)
treee0ff9bd91ab5bd52f5dc565263cc9424b3b2708f /src/gallium
parentd491ad1d364afa60eef5cf7b45f69f7007ab3dfd (diff)
gallium/u_vbuf: Protect against overflow with large instance divisors.
GTF-GLES3.gtf.GL3Tests.instanced_arrays.instanced_arrays_divisor uses -1 as a divisor, so we would overflow to count=0 and upload no data, triggering the assert below. We want to upload 1 element in this case, fixing the test on VC5. v2: Use some more obvious logic, and explain why we don't use the normal round_up(). Reviewed-by: Brian Paul <[email protected]>
Diffstat (limited to 'src/gallium')
-rw-r--r--src/gallium/auxiliary/util/u_vbuf.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/src/gallium/auxiliary/util/u_vbuf.c b/src/gallium/auxiliary/util/u_vbuf.c
index 95d7990c6ca..8a680d60a68 100644
--- a/src/gallium/auxiliary/util/u_vbuf.c
+++ b/src/gallium/auxiliary/util/u_vbuf.c
@@ -936,7 +936,16 @@ u_vbuf_upload_buffers(struct u_vbuf *mgr,
size = mgr->ve->src_format_size[i];
} else if (instance_div) {
/* Per-instance attrib. */
- unsigned count = (num_instances + instance_div - 1) / instance_div;
+
+ /* Figure out how many instances we'll render given instance_div. We
+ * can't use the typical div_round_up() pattern because the CTS uses
+ * instance_div = ~0 for a test, which overflows div_round_up()'s
+ * addition.
+ */
+ unsigned count = num_instances / instance_div;
+ if (count * instance_div != num_instances)
+ count++;
+
first += vb->stride * start_instance;
size = vb->stride * (count - 1) + mgr->ve->src_format_size[i];
} else {