--- /dev/null
+From 3a842bd5c6aa8eefa13c0174de3ab361e50bd672 Mon Sep 17 00:00:00 2001
+From: "Nicholas S. Husin" <nsh@golang.org>
+Date: Mon, 24 Nov 2025 14:56:23 -0500
+Subject: [PATCH] [release-branch.go1.24] crypto/x509: prevent
+ HostnameError.Error() from consuming excessive resource
+
+Constructing HostnameError.Error() takes O(N^2) runtime due to using a
+string concatenation in a loop. Additionally, there is no limit on how
+many names are included in the error message. As a result, a malicious
+attacker could craft a certificate with an infinite amount of names to
+unfairly consume resource.
+
+To remediate this, we will now use strings.Builder to construct the
+error message, preventing O(N^2) runtime. When a certificate has 100 or
+more names, we will also not print each name individually.
+
+Thanks to Philippe Antoine (Catena cyber) for reporting this issue.
+
+Updates #76445
+Fixes #76460
+Fixes CVE-2025-61729
+
+Change-Id: I6343776ec3289577abc76dad71766c491c1a7c81
+Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/3000
+Reviewed-by: Neal Patel <nealpatel@google.com>
+Reviewed-by: Damien Neil <dneil@google.com>
+Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/3220
+Reviewed-by: Roland Shoemaker <bracewell@google.com>
+Reviewed-on: https://go-review.googlesource.com/c/go/+/725820
+Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
+TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
+Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
+Reviewed-by: Mark Freeman <markfreeman@google.com>
+
+Upstream-Status: Backport [https://github.com/golang/go/commit/3a842bd5c6aa8eefa13c0174de3ab361e50bd672]
+CVE: CVE-2025-61729
+Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
+---
+ src/crypto/x509/verify.go | 21 ++++++++++-----
+ src/crypto/x509/verify_test.go | 47 ++++++++++++++++++++++++++++++++++
+ 2 files changed, 61 insertions(+), 7 deletions(-)
+
+diff --git a/src/crypto/x509/verify.go b/src/crypto/x509/verify.go
+index 3fdf65f..0ae8aef 100644
+--- a/src/crypto/x509/verify.go
++++ b/src/crypto/x509/verify.go
+@@ -100,31 +100,38 @@ type HostnameError struct {
+
+ func (h HostnameError) Error() string {
+ c := h.Certificate
++ maxNamesIncluded := 100
+
+ if !c.hasSANExtension() && matchHostnames(c.Subject.CommonName, h.Host) {
+ return "x509: certificate relies on legacy Common Name field, use SANs instead"
+ }
+
+- var valid string
++ var valid strings.Builder
+ if ip := net.ParseIP(h.Host); ip != nil {
+ // Trying to validate an IP
+ if len(c.IPAddresses) == 0 {
+ return "x509: cannot validate certificate for " + h.Host + " because it doesn't contain any IP SANs"
+ }
++ if len(c.IPAddresses) >= maxNamesIncluded {
++ return fmt.Sprintf("x509: certificate is valid for %d IP SANs, but none matched %s", len(c.IPAddresses), h.Host)
++ }
+ for _, san := range c.IPAddresses {
+- if len(valid) > 0 {
+- valid += ", "
++ if valid.Len() > 0 {
++ valid.WriteString(", ")
+ }
+- valid += san.String()
++ valid.WriteString(san.String())
+ }
+ } else {
+- valid = strings.Join(c.DNSNames, ", ")
++ if len(c.DNSNames) >= maxNamesIncluded {
++ return fmt.Sprintf("x509: certificate is valid for %d names, but none matched %s", len(c.DNSNames), h.Host)
++ }
++ valid.WriteString(strings.Join(c.DNSNames, ", "))
+ }
+
+- if len(valid) == 0 {
++ if valid.Len() == 0 {
+ return "x509: certificate is not valid for any names, but wanted to match " + h.Host
+ }
+- return "x509: certificate is valid for " + valid + ", not " + h.Host
++ return "x509: certificate is valid for " + valid.String() + ", not " + h.Host
+ }
+
+ // UnknownAuthorityError results when the certificate issuer is unknown
+diff --git a/src/crypto/x509/verify_test.go b/src/crypto/x509/verify_test.go
+index df9b0a2..223c250 100644
+--- a/src/crypto/x509/verify_test.go
++++ b/src/crypto/x509/verify_test.go
+@@ -10,13 +10,16 @@ import (
+ "crypto/ecdsa"
+ "crypto/elliptic"
+ "crypto/rand"
++ "crypto/rsa"
+ "crypto/x509/pkix"
+ "encoding/asn1"
+ "encoding/pem"
+ "errors"
+ "fmt"
+ "internal/testenv"
++ "log"
+ "math/big"
++ "net"
+ "os/exec"
+ "reflect"
+ "runtime"
+@@ -89,6 +92,26 @@ var verifyTests = []verifyTest{
+
+ errorCallback: expectHostnameError("certificate is valid for"),
+ },
++ {
++ name: "TooManyDNS",
++ leaf: generatePEMCertWithRepeatSAN(1677615892, 200, "fake.dns"),
++ roots: []string{generatePEMCertWithRepeatSAN(1677615892, 200, "fake.dns")},
++ currentTime: 1677615892,
++ dnsName: "www.example.com",
++ systemSkip: true, // does not chain to a system root
++
++ errorCallback: expectHostnameError("certificate is valid for 200 names, but none matched"),
++ },
++ {
++ name: "TooManyIPs",
++ leaf: generatePEMCertWithRepeatSAN(1677615892, 150, "4.3.2.1"),
++ roots: []string{generatePEMCertWithRepeatSAN(1677615892, 150, "4.3.2.1")},
++ currentTime: 1677615892,
++ dnsName: "1.2.3.4",
++ systemSkip: true, // does not chain to a system root
++
++ errorCallback: expectHostnameError("certificate is valid for 150 IP SANs, but none matched"),
++ },
+ {
+ name: "IPMissing",
+ leaf: googleLeaf,
+@@ -595,6 +618,30 @@ func nameToKey(name *pkix.Name) string {
+ return strings.Join(name.Country, ",") + "/" + strings.Join(name.Organization, ",") + "/" + strings.Join(name.OrganizationalUnit, ",") + "/" + name.CommonName
+ }
+
++func generatePEMCertWithRepeatSAN(currentTime int64, count int, san string) string {
++ cert := Certificate{
++ NotBefore: time.Unix(currentTime, 0),
++ NotAfter: time.Unix(currentTime, 0),
++ }
++ if ip := net.ParseIP(san); ip != nil {
++ cert.IPAddresses = slices.Repeat([]net.IP{ip}, count)
++ } else {
++ cert.DNSNames = slices.Repeat([]string{san}, count)
++ }
++ privKey, err := rsa.GenerateKey(rand.Reader, 4096)
++ if err != nil {
++ log.Fatal(err)
++ }
++ certBytes, err := CreateCertificate(rand.Reader, &cert, &cert, &privKey.PublicKey, privKey)
++ if err != nil {
++ log.Fatal(err)
++ }
++ return string(pem.EncodeToMemory(&pem.Block{
++ Type: "CERTIFICATE",
++ Bytes: certBytes,
++ }))
++}
++
+ const gtsIntermediate = `-----BEGIN CERTIFICATE-----
+ MIIFljCCA36gAwIBAgINAgO8U1lrNMcY9QFQZjANBgkqhkiG9w0BAQsFADBHMQsw
+ CQYDVQQGEwJVUzEiMCAGA1UEChMZR29vZ2xlIFRydXN0IFNlcnZpY2VzIExMQzEU
+--
+2.43.0
+
projects / thirdparty / openembedded / openembedded-core.git / commitdiff
