go: fix CVE-2025-47906

If the PATH environment variable contains paths which are executables
(rather than just directories), passing certain strings to LookPath
("", ".", and ".."), can result in the binaries listed in the PATH
being unexpectedly returned.

(From OE-Core rev: c4d81e32ee3fb7d05db2cfbfaaa8081841bc16ce)

Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 172 insertions, 0 deletions

diff --git a/meta/recipes-devtools/go/go-1.17.13.inc b/meta/recipes-devtools/go/go-1.17.13.inc
index 2052f4adbc..aab8e85c22 100644
--- a/meta/recipes-devtools/go/go-1.17.13.inc
+++ b/meta/recipes-devtools/go/go-1.17.13.inc
@@ -67,6 +67,7 @@ SRC_URI = "https://golang.org/dl/go${PV}.src.tar.gz;name=main \
            file://CVE-2025-47907-pre-0001.patch \
            file://CVE-2025-47907-pre-0002.patch \
            file://CVE-2025-47907.patch \
+           file://CVE-2025-47906.patch \
            "
 SRC_URI[main.sha256sum] = "a1a48b23afb206f95e7bbaa9b898d965f90826f6f1d1fc0c1d784ada0cd300fd"
 
diff --git a/meta/recipes-devtools/go/go-1.21/CVE-2025-47906.patch b/meta/recipes-devtools/go/go-1.21/CVE-2025-47906.patch
new file mode 100644
index 0000000000..272d1ed985
--- /dev/null
+++ b/meta/recipes-devtools/go/go-1.21/CVE-2025-47906.patch
@@ -0,0 +1,171 @@
+From 8fa31a2d7d9e60c50a3a94080c097b6e65773f4b Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Olivier=20Mengu=C3=A9?= <olivier.mengue@gmail.com>
+Date: Mon, 30 Jun 2025 16:58:59 +0200
+Subject: [PATCH] [release-branch.go1.23] os/exec: fix incorrect expansion of
+ "", "." and ".." in LookPath Fix incorrect expansion of "" and "." when $PATH
+ contains an executable file or, on Windows, a parent directory of a %PATH%
+ element contains an file with the same name as the %PATH% element but with
+ one of the %PATHEXT% extension (ex: C:\utils\bin is in PATH, and
+ C:\utils\bin.exe exists).
+
+Fix incorrect expansion of ".." when $PATH contains an element which is
+an the concatenation of the path to an executable file (or on Windows
+a path that can be expanded to an executable by appending a %PATHEXT%
+extension), a path separator and a name.
+
+"", "." and ".." are now rejected early with ErrNotFound.
+
+Fixes CVE-2025-47906
+Fixes #74803
+
+Change-Id: Ie50cc0a660fce8fbdc952a7f2e05c36062dcb50e
+Reviewed-on: https://go-review.googlesource.com/c/go/+/685755
+LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
+Auto-Submit: Damien Neil <dneil@google.com>
+Reviewed-by: Roland Shoemaker <roland@golang.org>
+Reviewed-by: Damien Neil <dneil@google.com>
+(cherry picked from commit e0b07dc)
+Reviewed-on: https://go-review.googlesource.com/c/go/+/691855
+Reviewed-by: Michael Knyszek <mknyszek@google.com>
+
+CVE: CVE-2025-47906
+
+Upstream-Status: Backport [https://github.com/golang/go/commit/8fa31a2d7d9e60c50a3a94080c097b6e65773f4b]
+
+Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
+---
+ src/internal/execabs/execabs_test.go | 55 ++++++++++++++++++++++++++++
+ src/os/exec/exec.go                  |  9 +++++
+ src/os/exec/lp_plan9.go              |  4 ++
+ src/os/exec/lp_unix.go               |  4 ++
+ src/os/exec/lp_windows.go            |  4 ++
+ 5 files changed, 76 insertions(+)
+
+diff --git a/src/internal/execabs/execabs_test.go b/src/internal/execabs/execabs_test.go
+index 97a3f39..99fd64b 100644
+--- a/src/internal/execabs/execabs_test.go
++++ b/src/internal/execabs/execabs_test.go
+@@ -100,4 +100,59 @@ func TestLookPath(t *testing.T) {
+        } else if err.Error() != expectedErr {
+                t.Errorf("LookPath returned unexpected error: want %q, got %q", expectedErr, err.Error())
+        }
++       checker := func(test string) func(t *testing.T) {
++               return func(t *testing.T) {
++                       t.Helper()
++                       t.Logf("PATH=%s", os.Getenv("PATH"))
++                       p, err := LookPath(test)
++                       if err == nil {
++                               t.Errorf("%q: error expected, got nil", test)
++                       }
++                       if p != "" {
++                               t.Errorf("%q: path returned should be \"\". Got %q", test, p)
++                       }
++               }
++       }
++
++       // Reference behavior for the next test
++       t.Run(pathVar+"=$OTHER2", func(t *testing.T) {
++               t.Run("empty", checker(""))
++               t.Run("dot", checker("."))
++               t.Run("dotdot1", checker("abc/.."))
++               t.Run("dotdot2", checker(".."))
++       })
++
++       // Test the behavior when PATH contains an executable file which is not a directory
++       t.Run(pathVar+"=exe", func(t *testing.T) {
++               // Inject an executable file (not a directory) in PATH.
++               // Use our own binary os.Args[0].
++               testenv.MustHaveExec(t)
++               exe, err := os.Executable()
++               if err != nil {
++                       t.Fatal(err)
++               }
++
++               t.Setenv(pathVar, exe)
++               t.Run("empty", checker(""))
++               t.Run("dot", checker("."))
++               t.Run("dotdot1", checker("abc/.."))
++               t.Run("dotdot2", checker(".."))
++       })
++
++       // Test the behavior when PATH contains an executable file which is not a directory
++       t.Run(pathVar+"=exe/xx", func(t *testing.T) {
++               // Inject an executable file (not a directory) in PATH.
++               // Use our own binary os.Args[0].
++               testenv.MustHaveExec(t)
++               exe, err := os.Executable()
++               if err != nil {
++                       t.Fatal(err)
++               }
++
++               t.Setenv(pathVar, filepath.Join(exe, "xx"))
++               t.Run("empty", checker(""))
++               t.Run("dot", checker("."))
++               t.Run("dotdot1", checker("abc/.."))
++               t.Run("dotdot2", checker(".."))
++       })
+ }
+diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
+index 505de58..84fd82f 100644
+--- a/src/os/exec/exec.go
++++ b/src/os/exec/exec.go
+@@ -790,3 +790,12 @@ func addCriticalEnv(env []string) []string {
+        }
+        return append(env, "SYSTEMROOT="+os.Getenv("SYSTEMROOT"))
+ }
++// validateLookPath excludes paths that can't be valid
++// executable names. See issue #74466 and CVE-2025-47906.
++func validateLookPath(s string) error {
++       switch s {
++       case "", ".", "..":
++               return ErrNotFound
++       }
++       return nil
++}
+diff --git a/src/os/exec/lp_plan9.go b/src/os/exec/lp_plan9.go
+index e8826a5..ed9f6e3 100644
+--- a/src/os/exec/lp_plan9.go
++++ b/src/os/exec/lp_plan9.go
+@@ -33,6 +33,10 @@ func findExecutable(file string) error {
+ // The result may be an absolute path or a path relative to the current directory.
+ func LookPath(file string) (string, error) {
+        // skip the path lookup for these prefixes
++       if err := validateLookPath(file); err != nil {
++               return "", &Error{file, err}
++       }
++
+        skip := []string{"/", "#", "./", "../"}
+
+        for _, p := range skip {
+diff --git a/src/os/exec/lp_unix.go b/src/os/exec/lp_unix.go
+index d1d246a..1b27f2b 100644
+--- a/src/os/exec/lp_unix.go
++++ b/src/os/exec/lp_unix.go
+@@ -38,6 +38,10 @@ func LookPath(file string) (string, error) {
+        // (only bypass the path if file begins with / or ./ or ../)
+        // but that would not match all the Unix shells.
+
++       if err := validateLookPath(file); err != nil {
++               return "", &Error{file, err}
++       }
++
+        if strings.Contains(file, "/") {
+                err := findExecutable(file)
+                if err == nil {
+diff --git a/src/os/exec/lp_windows.go b/src/os/exec/lp_windows.go
+index e7a2cdf..7a1d6fb 100644
+--- a/src/os/exec/lp_windows.go
++++ b/src/os/exec/lp_windows.go
+@@ -58,6 +58,10 @@ func findExecutable(file string, exts []string) (string, error) {
+ // a suitable candidate.
+ // The result may be an absolute path or a path relative to the current directory.
+ func LookPath(file string) (string, error) {
++       if err := validateLookPath(file); err != nil {
++               return "", &Error{file, err}
++       }
++
+        var exts []string
+        x := os.Getenv(`PATHEXT`)
+        if x != "" {
+--
+2.40.0