From c962188655923aae9bb94f3ed48e792e845bf627 Mon Sep 17 00:00:00 2001
From: ashutosh0x <ashutoshkumarsingh0x@gmail.com>
Date: Wed, 11 Feb 2026 22:33:28 +0530
Subject: [PATCH] Fix zero-sized allocation crash on Windows

On Windows, _aligned_malloc(0) returns NULL, which MuJoCo interprets as a fatal out-of-memory error. This causes crashes on models with empty arrays.

Ensure a minimum allocation of 64 bytes for any 0-sized request.

Fixes #2992
---
 src/engine/engine_util_errmem.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/engine/engine_util_errmem.c b/src/engine/engine_util_errmem.c
index cbd373d3..1920bdf8 100644
--- a/src/engine/engine_util_errmem.c
+++ b/src/engine/engine_util_errmem.c
@@ -207,8 +207,10 @@ void* mju_malloc(size_t size) {
   // default allocator
   else {
     // pad size to multiple of 64
-    if ((size%64)) {
-      size += 64 - (size%64);
+    if (size == 0) {
+      size = 64;
+    } else if ((size % 64)) {
+      size += 64 - (size % 64);
     }
 
     // allocate