From e8e7facfaa47bf21007c0a1c679debba52ec3ea0 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Mon, 11 Jan 2021 09:41:54 -0500 Subject: [PATCH] [release-branch.go1.15-security] cmd/go: pass resolved CC, GCCGO to cgo This makes sure the go command and cgo agree about exactly which compiler is being used. This issue was reported by RyotaK. Fixes CVE-2021-3115. Change-Id: If171c5c8b2523efb5ea2d957e5ad1380a038149c Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/949416 Reviewed-by: Ian Lance Taylor Reviewed-by: Jay Conrod (cherry picked from commit 4cf399ca38587a6e4a3e85b494cd9a9b4cc53378) Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/955293 Reviewed-by: Katie Hockman --- src/cmd/go/internal/work/action.go | 3 +++ src/cmd/go/internal/work/exec.go | 30 +++++++++++++++++++++++------- 2 files changed, 26 insertions(+), 7 deletions(-) diff --git a/src/cmd/go/internal/work/action.go b/src/cmd/go/internal/work/action.go index 6b5f9e4807..03ca301bdd 100644 --- a/src/cmd/go/internal/work/action.go +++ b/src/cmd/go/internal/work/action.go @@ -56,6 +56,9 @@ type Builder struct { id sync.Mutex toolIDCache map[string]string // tool name -> tool ID buildIDCache map[string]string // file name -> build ID + + cgoEnvOnce sync.Once + cgoEnvCache []string } // NOTE: Much of Action would not need to be exported if not for test. diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go index dc0c4fc344..3c39734590 100644 --- a/src/cmd/go/internal/work/exec.go +++ b/src/cmd/go/internal/work/exec.go @@ -1080,10 +1080,8 @@ func (b *Builder) vet(a *Action) error { return err } - env := b.cCompilerEnv() - if cfg.BuildToolchainName == "gccgo" { - env = append(env, "GCCGO="+BuildToolchain.compiler()) - } + // TODO(rsc): Why do we pass $GCCGO to go vet? + env := b.cgoEnv() p := a.Package tool := VetTool @@ -2014,6 +2012,24 @@ func (b *Builder) cCompilerEnv() []string { return []string{"TERM=dumb"} } +// cgoEnv returns environment variables to set when running cgo. +// Some of these pass through to cgo running the C compiler, +// so it includes cCompilerEnv. +func (b *Builder) cgoEnv() []string { + b.cgoEnvOnce.Do(func() { + cc, err := exec.LookPath(b.ccExe()[0]) + if err != nil || filepath.Base(cc) == cc { // reject relative path + cc = "/missing-cc" + } + gccgo := GccgoBin + if filepath.Base(gccgo) == gccgo { // reject relative path + gccgo = "/missing-gccgo" + } + b.cgoEnvCache = append(b.cCompilerEnv(), "CC="+cc, "GCCGO="+gccgo) + }) + return b.cgoEnvCache +} + // mkdir makes the named directory. func (b *Builder) Mkdir(dir string) error { // Make Mkdir(a.Objdir) a no-op instead of an error when a.Objdir == "". @@ -2603,13 +2619,13 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo // along to the host linker. At this point in the code, cgoLDFLAGS // consists of the original $CGO_LDFLAGS (unchecked) and all the // flags put together from source code (checked). - cgoenv := b.cCompilerEnv() + cgoenv := b.cgoEnv() if len(cgoLDFLAGS) > 0 { flags := make([]string, len(cgoLDFLAGS)) for i, f := range cgoLDFLAGS { flags[i] = strconv.Quote(f) } - cgoenv = []string{"CGO_LDFLAGS=" + strings.Join(flags, " ")} + cgoenv = append(cgoenv, "CGO_LDFLAGS="+strings.Join(flags, " ")) } if cfg.BuildToolchainName == "gccgo" { @@ -2824,7 +2840,7 @@ func (b *Builder) dynimport(a *Action, p *load.Package, objdir, importGo, cgoExe if p.Standard && p.ImportPath == "runtime/cgo" { cgoflags = []string{"-dynlinker"} // record path to dynamic linker } - return b.run(a, p.Dir, p.ImportPath, b.cCompilerEnv(), cfg.BuildToolexec, cgoExe, "-dynpackage", p.Name, "-dynimport", dynobj, "-dynout", importGo, cgoflags) + return b.run(a, p.Dir, p.ImportPath, b.cgoEnv(), cfg.BuildToolexec, cgoExe, "-dynpackage", p.Name, "-dynimport", dynobj, "-dynout", importGo, cgoflags) } // Run SWIG on all SWIG input files.