https://git.ruby-lang.org/ruby.git/commit/?id=9fb60672d5

From 9fb60672d55162a92ab7e97b000a7e277458aab1 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <tenderlove@r...>
Date: Wed, 23 Sep 2020 20:06:38 -0700
Subject: Fix a use-after-free bug reported by ASAN

If a fiber and thread are collected at the same time, the thread might
get collected first and the pointer on the fiber will go bad.  I don't
think we need to check whether or not this is the main fiber in order to
release its stack

diff --git a/cont.c b/cont.c
index 0304f4c..561398d 100644
--- a/cont.c
+++ b/cont.c
@@ -940,9 +940,7 @@ cont_free(void *ptr) https://github.com/ruby/ruby/blob/trunk/cont.c#L940
     else {
         rb_fiber_t *fiber = (rb_fiber_t*)cont;
         coroutine_destroy(&fiber->context);
-        if (!fiber_is_root_p(fiber)) {
-            fiber_stack_release(fiber);
-        }
+        fiber_stack_release(fiber);
     }
 
     RUBY_FREE_UNLESS_NULL(cont->saved_vm_stack.ptr);
-- 
cgit v0.10.2


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