From f13e459e4b479fb658568039386909f4999f3989 Mon Sep 17 00:00:00 2001
From: K Pamnany <kpamnany@users.noreply.github.com>
Date: Mon, 8 Dec 2025 12:22:29 -0500
Subject: [PATCH] Initialize big object header properly

Prevent uninitialized memory from causing an assertion failure.
---
 src/gc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/gc.c b/src/gc.c
index 98ed32cd4a54a..65b52b7130dcc 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -1014,6 +1014,7 @@ STATIC_INLINE jl_value_t *jl_gc_big_alloc_inner(jl_ptls_t ptls, size_t sz)
     memset(v, 0xee, allocsz);
 #endif
     v->sz = allocsz;
+    v->header = 0;
     gc_big_object_link(ptls->gc_tls.heap.young_generation_of_bigvals, v);
     return jl_valueof(&v->header);
 }