From 47c424b767858580d794f9883b45df4dab6d524a Mon Sep 17 00:00:00 2001
From: Luke Gruber <luke.gruber@shopify.com>
Date: Tue, 21 Jul 2026 10:53:47 -0400
Subject: [PATCH] Crash handler assumes box is present

rb_current_box_in_crash_report() calls GET_EC(), which assumes ec is
present. The crash handler should work when called from non-Ruby
threads (no ec).
---
 box.c     |  3 +++
 vm_dump.c | 14 +++++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/box.c b/box.c
index b6f52a66b69..d9be82c6293 100644
--- a/box.c
+++ b/box.c
@@ -103,6 +103,7 @@ rb_main_box(void)
     return main_box;
 }
 
+// NOTE: must be called by Ruby thread
 const rb_box_t *
 rb_current_box(void)
 {
@@ -121,6 +122,7 @@ rb_current_box(void)
     return rb_vm_current_box(GET_EC());
 }
 
+// NOTE: must be called by Ruby thread
 const rb_box_t *
 rb_loading_box(void)
 {
@@ -132,6 +134,7 @@ rb_loading_box(void)
     return rb_vm_loading_box(GET_EC());
 }
 
+// NOTE: must be called by Ruby thread
 const rb_box_t *
 rb_current_box_in_crash_report(void)
 {
diff --git a/vm_dump.c b/vm_dump.c
index 6c8342c88ee..f60c0ed6aa2 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -1419,16 +1419,20 @@ rb_vm_bugreport(const void *ctx, FILE *errout)
     enum {other_runtime_info = 0};
 #endif
     const rb_vm_t *const vm = GET_VM();
-    const rb_box_t *current_box = rb_current_box_in_crash_report();
     const rb_execution_context_t *ec = rb_current_execution_context(false);
-    VALUE loaded_features;
+    rb_box_t *current_box = NULL;
+    VALUE loaded_features = 0;
+    if (ec) {
+        current_box = (rb_box_t*)rb_current_box_in_crash_report();
+    }
+    else {
+        current_box = (rb_box_t*)rb_main_box();
+        if (!current_box) current_box = (rb_box_t*)rb_root_box();
+    }
 
     if (current_box) {
         loaded_features = current_box->loaded_features;
     }
-    else {
-        loaded_features = rb_root_box()->loaded_features;
-    }
 
     if (vm && ec) {
         rb_vmdebug_stack_dump_raw(ec, ec->cfp, errout);