commit ff5addb6be2fb3001f0cb026c3e4931090a85664
author Ian Lance Taylor <iant@golang.org> Mon Nov 02 21:31:06 2020 -0800
committer Filippo Valsorda <filippo@golang.org> Thu Nov 12 15:40:27 2020 +0100
tree ca74c76ec421b7f1e3a1246c4a7d73f5773b2a72
parent 57ffa7b101296229328eaec6219a7c211a4ac49b

[release-branch.go1.14-security] cmd/go: in cgoflags, permit -DX1, prohibit -Wp,-D,opt

Restrict -D and -U to ASCII C identifiers, but do permit trailing digits.
When using -Wp, prohibit commas in -D values.

Thanks to Imre Rad (https://www.linkedin.com/in/imre-rad-2358749b) for reporting this.

Fixes CVE-2020-28367

Change-Id: Ibfc4dfdd6e6c258e131448e7682610c44eee9492
Reviewed-on: https://go-review.googlesource.com/c/go/+/267277
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/899923
Reviewed-by: Filippo Valsorda <valsorda@google.com>

src/cmd/go/internal/work/security.go

diff --git a/src/cmd/go/internal/work/security.go b/src/cmd/go/internal/work/security.go
index 0ce1664..a823b20 100644
--- a/src/cmd/go/internal/work/security.go
+++ b/src/cmd/go/internal/work/security.go
@@ -42,8 +42,8 @@
 var re = lazyregexp.New
 
 var validCompilerFlags = []*lazyregexp.Regexp{
-	re(`-D([A-Za-z_].*)`),
-	re(`-U([A-Za-z_]*)`),
+	re(`-D([A-Za-z_][A-Za-z0-9_]*)(=[^@\-]*)?`),
+	re(`-U([A-Za-z_][A-Za-z0-9_]*)`),
 	re(`-F([^@\-].*)`),
 	re(`-I([^@\-].*)`),
 	re(`-O`),
@@ -51,8 +51,8 @@
 	re(`-W`),
 	re(`-W([^@,]+)`), // -Wall but not -Wa,-foo.
 	re(`-Wa,-mbig-obj`),
-	re(`-Wp,-D([A-Za-z_].*)`),
-	re(`-Wp,-U([A-Za-z_]*)`),
+	re(`-Wp,-D([A-Za-z_][A-Za-z0-9_]*)(=[^@,\-]*)?`),
+	re(`-Wp,-U([A-Za-z_][A-Za-z0-9_]*)`),
 	re(`-ansi`),
 	re(`-f(no-)?asynchronous-unwind-tables`),
 	re(`-f(no-)?blocks`),

src/cmd/go/internal/work/security_test.go

diff --git a/src/cmd/go/internal/work/security_test.go b/src/cmd/go/internal/work/security_test.go
index 6b85c40b..bd707ff 100644
--- a/src/cmd/go/internal/work/security_test.go
+++ b/src/cmd/go/internal/work/security_test.go
@@ -13,6 +13,7 @@
 	{"-DFOO"},
 	{"-Dfoo=bar"},
 	{"-Ufoo"},
+	{"-Ufoo1"},
 	{"-F/Qt"},
 	{"-I/"},
 	{"-I/etc/passwd"},
@@ -24,6 +25,8 @@
 	{"-Wall"},
 	{"-Wp,-Dfoo=bar"},
 	{"-Wp,-Ufoo"},
+	{"-Wp,-Dfoo1"},
+	{"-Wp,-Ufoo1"},
 	{"-fobjc-arc"},
 	{"-fno-objc-arc"},
 	{"-fomit-frame-pointer"},
@@ -78,6 +81,8 @@
 	{"-O@1"},
 	{"-Wa,-foo"},
 	{"-W@foo"},
+	{"-Wp,-DX,-D@X"},
+	{"-Wp,-UX,-U@X"},
 	{"-g@gdb"},
 	{"-g-gdb"},
 	{"-march=@dawn"},