cmd/go/internal/work: sanitize flags before invoking 'pkg-config'

The addition of CgoPkgConfig allowed execution with flags not
matching the safelist. In order to prevent potential arbitrary
code execution at build time, ensure that flags are validated
prior to invoking the 'pkg-config' binary.

Thank you to RyotaK (https://ryotak.net) of GMO Flatt Security Inc.
for reporting this issue.

Fixes CVE-2025-61731
Fixes #77100

Change-Id: Ic51b41f1f7e697ab98c9c32c6fae35f217f7f364
Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/3240
Reviewed-by: Nicholas Husin <husin@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/736711
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 0afdce235688088bab6051584c7af6c6b1c134df..c497135612ece6e14a1c74ade3485fcf30159caa 100644 (file)
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -1788,6 +1788,14 @@ func (b *Builder) getPkgConfigFlags(a *Action, p *load.Package) (cflags, ldflags
                                return nil, nil, fmt.Errorf("invalid pkg-config package name: %s", pkg)
                        }
                }
+
+               // Running 'pkg-config' can cause execution of
+               // arbitrary code using flags that are not in
+               // the safelist.
+               if err := checkCompilerFlags("CFLAGS", "pkg-config --cflags", pcflags); err != nil {
+                       return nil, nil, err
+               }
+
                var out []byte
                out, err = sh.runOut(p.Dir, nil, b.PkgconfigCmd(), "--cflags", pcflags, "--", pkgs)
                if err != nil {

diff --git a/src/cmd/go/internal/work/security.go b/src/cmd/go/internal/work/security.go
index ffa83e05917d5241bf50ca45fed376dd6b48560b..80b3f8797cc3cee1574931394e11e2ccd98cf05d 100644 (file)
--- a/src/cmd/go/internal/work/security.go
+++ b/src/cmd/go/internal/work/security.go
@@ -129,6 +129,7 @@ var validCompilerFlags = []*lazyregexp.Regexp{
        re(`-pedantic(-errors)?`),
        re(`-pipe`),
        re(`-pthread`),
+       re(`--static`),
        re(`-?-std=([^@\-].*)`),
        re(`-?-stdlib=([^@\-].*)`),
        re(`--sysroot=([^@\-].*)`),