From 3000f7cdb1123f2a4d8b690d4292c541359c670c Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Thu, 3 Sep 2026 20:25:44 +0200
Subject: [PATCH] FFI: Adjust J->maxslot after ffi.offsetof.

Reported by Elias Hogstvedt. #1514
---
 src/lj_record.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/lj_record.c b/src/lj_record.c
index a1039d15..437735b6 100644
--- a/src/lj_record.c
+++ b/src/lj_record.c
@@ -1712,6 +1712,8 @@ void lj_record_ins(jit_State *J)
       {
 	BCReg s;
 	TValue *tv = J->L->base;
+	ptrdiff_t delta = J->L->top - tv;
+	if (J->maxslot > (BCReg)delta) J->maxslot = (BCReg)delta;
 	for (s = 0; s < J->maxslot; s++)  /* Constify stack slots (if any). */
 	  if (J->base[s] == TREF_NIL && !tvisnil(&tv[s]))
 	    J->base[s] = lj_record_constify(J, &tv[s]);