From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Tue, 25 May 2021 14:24:41 +0000 (+0200)
Subject: os: avoid finalizer race in windows process object
X-Git-Tag: go1.17beta1~38
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=3a9d906edc;p=gostls13.git

os: avoid finalizer race in windows process object

If proc.Release is called concurrently, a handle will be double-freed.

Change-Id: I0c0c32e312e07bc8615e0bf9e9b691214444d8d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/322510
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---

diff --git a/src/os/exec_windows.go b/src/os/exec_windows.go
index b59a01a75e..239bed198f 100644
--- a/src/os/exec_windows.go
+++ b/src/os/exec_windows.go
@@ -69,7 +69,7 @@ func (p *Process) signal(sig Signal) error {
 }
 
 func (p *Process) release() error {
-	handle := atomic.LoadUintptr(&p.handle)
+	handle := atomic.SwapUintptr(&p.handle, uintptr(syscall.InvalidHandle))
 	if handle == uintptr(syscall.InvalidHandle) {
 		return syscall.EINVAL
 	}
@@ -77,7 +77,6 @@ func (p *Process) release() error {
 	if e != nil {
 		return NewSyscallError("CloseHandle", e)
 	}
-	atomic.StoreUintptr(&p.handle, uintptr(syscall.InvalidHandle))
 	// no need for a finalizer anymore
 	runtime.SetFinalizer(p, nil)
 	return nil