net/http: preserve nil values in Header.Clone
ReverseProxy makes a distinction between nil and zero-length header values.
Avoid losing nil-ness when cloning a request.
Thanks to Christian Mehlmauer for discovering this.
Fixes #53423
Fixes CVE-2022-32148
Change-Id: Ice369cdb4712e2d62e25bb881b080847aa4801f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/412857
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/net/http/header.go b/src/net/http/header.go
index 6487e50..6437f2d 100644
--- a/src/net/http/header.go
+++ b/src/net/http/header.go
@@ -103,6 +103,12 @@
sv := make([]string, nv) // shared backing array for headers' values
h2 := make(Header, len(h))
for k, vv := range h {
+ if vv == nil {
+ // Preserve nil values. ReverseProxy distinguishes
+ // between nil and zero-length header values.
+ h2[k] = nil
+ continue
+ }
n := copy(sv, vv)
h2[k] = sv[:n:n]
sv = sv[n:]
diff --git a/src/net/http/header_test.go b/src/net/http/header_test.go
index 57d16f5..0b13d31 100644
--- a/src/net/http/header_test.go
+++ b/src/net/http/header_test.go
@@ -248,6 +248,11 @@
in: Header{"foo": {"bar"}},
want: Header{"foo": {"bar"}},
},
+ {
+ name: "nil value",
+ in: Header{"foo": nil},
+ want: Header{"foo": nil},
+ },
}
for _, tt := range tests {
