From d69e6f63c349741a450e9de9585ad555babefad4 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Wed, 20 Nov 2024 19:24:56 +0000
Subject: [PATCH] runtime: keep cleanup closure alive across adding the cleanup
special
This is similar to the weak handle bug in #70455. In short, there's a
window where a heap-allocated value is only visible through a special
that has not been made visible to the GC yet.
For #70455.
Change-Id: Ic2bb2c60d422a5bc5dab8d971cfc26ff6d7622bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/630277
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
---
src/runtime/mheap.go | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 0c3d6e669e..4b9734da5f 100644
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -2057,6 +2057,11 @@ func addCleanup(p unsafe.Pointer, f *funcval) uint64 {
// special isn't part of the GC'd heap.
scanblock(uintptr(unsafe.Pointer(&s.fn)), goarch.PtrSize, &oneptrmask[0], gcw, nil)
}
+ // Keep f alive. There's a window in this function where it's
+ // only reachable via the special while the special hasn't been
+ // added to the specials list yet. This is similar to a bug
+ // discovered for weak handles, see #70455.
+ KeepAlive(f)
return id
}