syscall: do not use handle lists on windows when NoInheritHandles is true

If NoInheritHandles is passed, then we shouldn't attempt to do anything
with handle lists. Otherwise CreateProcess fails with invalid param,
because it's being told both to not inherit handles and to inherit
certain handles.

This commit fixes that by using the same logic for handle lists as it
does for enabling or disabling handle inheritance. It also adds a test
to make sure this doesn't regress again.

Fixes #48040

Change-Id: I507261baeec263091738ab90157a991d917dc92f
Reviewed-on: https://go-review.googlesource.com/c/go/+/350411
Reviewed-by: Patrik Nyblom <pnyb@google.com>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>

2 files changed, 19 insertions, 3 deletions

diff --git a/src/os/exec/exec_windows_test.go b/src/os/exec/exec_windows_test.go
index fbccffec0e..bd4dfb31da 100644
--- a/src/os/exec/exec_windows_test.go
+++ b/src/os/exec/exec_windows_test.go
@@ -10,6 +10,7 @@ package exec_test
 import (
 	"io"
 	"os"
+	"os/exec"
 	"strconv"
 	"syscall"
 	"testing"
@@ -41,3 +42,16 @@ func TestPipePassing(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestNoInheritHandles(t *testing.T) {
+	cmd := exec.Command("cmd", "/c exit 88")
+	cmd.SysProcAttr = &syscall.SysProcAttr{NoInheritHandles: true}
+	err := cmd.Run()
+	exitError, ok := err.(*exec.ExitError)
+	if !ok {
+		t.Fatalf("got error %v; want ExitError", err)
+	}
+	if exitError.ExitCode() != 88 {
+		t.Fatalf("got exit code %d; want 88", exitError.ExitCode())
+	}
+}
diff --git a/src/syscall/exec_windows.go b/src/syscall/exec_windows.go
index 18d15028c3..9d10d6a512 100644
--- a/src/syscall/exec_windows.go
+++ b/src/syscall/exec_windows.go
@@ -390,8 +390,10 @@ func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle
 	}
 	fd = fd[:j]
 
+	willInheritHandles := len(fd) > 0 && !sys.NoInheritHandles
+
 	// Do not accidentally inherit more than these handles.
-	if len(fd) > 0 {
+	if willInheritHandles {
 		err = updateProcThreadAttribute(si.ProcThreadAttributeList, 0, _PROC_THREAD_ATTRIBUTE_HANDLE_LIST, unsafe.Pointer(&fd[0]), uintptr(len(fd))*unsafe.Sizeof(fd[0]), nil, nil)
 		if err != nil {
 			return 0, 0, err
@@ -401,9 +403,9 @@ func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle
 	pi := new(ProcessInformation)
 	flags := sys.CreationFlags | CREATE_UNICODE_ENVIRONMENT | _EXTENDED_STARTUPINFO_PRESENT
 	if sys.Token != 0 {
-		err = CreateProcessAsUser(sys.Token, argv0p, argvp, sys.ProcessAttributes, sys.ThreadAttributes, len(fd) > 0 && !sys.NoInheritHandles, flags, createEnvBlock(attr.Env), dirp, &si.StartupInfo, pi)
+		err = CreateProcessAsUser(sys.Token, argv0p, argvp, sys.ProcessAttributes, sys.ThreadAttributes, willInheritHandles, flags, createEnvBlock(attr.Env), dirp, &si.StartupInfo, pi)
 	} else {
-		err = CreateProcess(argv0p, argvp, sys.ProcessAttributes, sys.ThreadAttributes, len(fd) > 0 && !sys.NoInheritHandles, flags, createEnvBlock(attr.Env), dirp, &si.StartupInfo, pi)
+		err = CreateProcess(argv0p, argvp, sys.ProcessAttributes, sys.ThreadAttributes, willInheritHandles, flags, createEnvBlock(attr.Env), dirp, &si.StartupInfo, pi)
 	}
 	if err != nil {
 		return 0, 0, err