From: Roland Shoemaker <roland@golang.org>
Date: Fri, 2 Jun 2023 15:49:47 +0000 (-0700)
Subject: syscall: don't panic when argv is nil on freebsd
X-Git-Tag: go1.21rc1~104
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=96b79bd3208078835d6a1b9b8c7050554eccc734;p=gostls13.git

syscall: don't panic when argv is nil on freebsd

The workaround in CL 69970044 introduced a panic when StartProcess is
called with empty argv. Check the length before trying to access it.

Change-Id: Ic948d86c7067a21c484ba24e100d1f1f80179730
Reviewed-on: https://go-review.googlesource.com/c/go/+/500415
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
---

diff --git a/src/syscall/exec_unix.go b/src/syscall/exec_unix.go
index 4b9c04db83..14edd023d3 100644
--- a/src/syscall/exec_unix.go
+++ b/src/syscall/exec_unix.go
@@ -165,7 +165,7 @@ func forkExec(argv0 string, argv []string, attr *ProcAttr) (pid int, err error)
 		return 0, err
 	}
 
-	if (runtime.GOOS == "freebsd" || runtime.GOOS == "dragonfly") && len(argv[0]) > len(argv0) {
+	if (runtime.GOOS == "freebsd" || runtime.GOOS == "dragonfly") && len(argv) > 0 && len(argv[0]) > len(argv0) {
 		argvp[0] = argv0p
 	}
 
diff --git a/src/syscall/exec_unix_test.go b/src/syscall/exec_unix_test.go
index 2e5e3df374..9627317bb3 100644
--- a/src/syscall/exec_unix_test.go
+++ b/src/syscall/exec_unix_test.go
@@ -387,3 +387,15 @@ func TestRlimitRestored(t *testing.T) {
 		t.Errorf("exec rlimit = %d, want %d", v, orig)
 	}
 }
+
+func TestForkExecNilArgv(t *testing.T) {
+	defer func() {
+		if p := recover(); p != nil {
+			t.Fatal("forkExec panicked")
+		}
+	}()
+
+	// We don't really care what the result of forkExec is, just that it doesn't
+	// panic, so we choose something we know won't actually spawn a process (probably).
+	syscall.ForkExec("/dev/null", nil, nil)
+}