Add safeguard in case num_tris diverges

Yann Noutary · facebook-github-bot · commit 91c9f341377e · 2024-11-20T01:24:28.000-08:00
Summary:
This PR fixes adds a safeguard preventing num_tris to overflow in `MAX_TRIS`-length arrays. The update rule of `num_tris` is bounded :

 - max(num_tris(t)) = 2*num_tris(t-1)
 - num_tris(0) = 12
 - t &lt;= 6

So :
 - max(num_tris) = 2^6*12
 - max(num_tris) = 768

Reviewed By: bottler

Differential Revision: D66162573

fbshipit-source-id: e269a79c75c6cc33306986b1f1256cffbe96c730
diff --git a/pytorch3d/csrc/iou_box3d/iou_utils.cuh b/pytorch3d/csrc/iou_box3d/iou_utils.cuh
@@ -728,7 +728,7 @@ __device__ inline int BoxIntersections(
       }
     }
     // Update the face_verts_out tris
-    num_tris = offset;
+    num_tris = min(MAX_TRIS, offset);
     for (int j = 0; j < num_tris; ++j) {
       face_verts_out[j] = tri_verts_updated[j];
     }

Original file line number	Diff line number	Diff line change
`@@ -728,7 +728,7 @@ __device__ inline int BoxIntersections(`
`728`	`728`	`}`
`729`	`729`	`}`
`730`	`730`	`// Update the face_verts_out tris`
`731`		`- num_tris = offset;`
	`731`	`+ num_tris = min(MAX_TRIS, offset);`
`732`	`732`	`for (int j = 0; j < num_tris; ++j) {`
`733`	`733`	`face_verts_out[j] = tri_verts_updated[j];`
`734`	`734`	`}`