merge revision(s) de51bbcb544651fb499dd4cc757a2bf6f3b439cf: [Backport #18816]

	Use VM Lock when mutating waiting threads list

	`rb_thread_wait_for_single_fd` needs to mutate the `waiting_fds` list
	that is stored on the VM.  We need to delete the FD from the list before
	returning, and deleting from the list requires a VM lock (because the
	list is a global).

	[Bug #18816] [ruby-core:108771]

	Co-Authored-By: Alan Wu <alanwu@ruby-lang.org>
	---
	 thread.c | 6 +++++-
	 1 file changed, 5 insertions(+), 1 deletion(-)

1 files changed, 5 insertions, 1 deletions

diff --git a/thread.c b/thread.c
index cf6e89327e..9476a7986a 100644
--- a/thread.c
+++ b/thread.c
@@ -4501,7 +4501,11 @@ select_single_cleanup(VALUE ptr)
 {
     struct select_args *args = (struct select_args *)ptr;
 
-    list_del(&args->wfd.wfd_node);
+    RB_VM_LOCK_ENTER();
+    {
+        list_del(&args->wfd.wfd_node);
+    }
+    RB_VM_LOCK_LEAVE();
     if (args->read) rb_fd_term(args->read);
     if (args->write) rb_fd_term(args->write);
     if (args->except) rb_fd_term(args->except);