From 0356db022da819176d9d0eacab63d4c2c852f876 Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Tue, 20 Mar 2018 10:42:12 -0700 Subject: [PATCH] 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 --- src/gallium/auxiliary/util/u_vbuf.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) 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 { -- 2.30.2