Update to Go 1.26.4

VERSION

@@ -1,2 +1,2 @@
-go1.26.3
-time 2026-05-04T20:36:18Z
+go1.26.4
+time 2026-05-29T15:26:39Z

src/cmd/compile/internal/ssa/_gen/AMD64.rules

@@ -909,7 +909,8 @@
 (LEA(Q|L)2 [0] {s} (ADD(Q|L) x x) x) && s == nil => (SHL(Q|L)const [2] x)
 
 // (x + x) << 2 -> x << 3 and similar
-(SHL(Q|L)const [c] (ADD(Q|L) x x))  => (SHL(Q|L)const [c+1] x)
+(SHLQconst [c] (ADDQ x x)) && c < 63 => (SHLQconst [c+1] x)
+(SHLLconst [c] (ADDL x x)) && c < 31 => (SHLLconst [c+1] x)
 
 // reverse ordering of compare instruction
 (SETL (InvertFlags x)) => (SETG x)

src/cmd/go.mod

@@ -11,7 +11,7 @@ require (
 	golang.org/x/sys v0.39.0
 	golang.org/x/telemetry v0.0.0-20251128220624-abf20d0e57ec
 	golang.org/x/term v0.38.0
-	golang.org/x/tools v0.39.1-0.20260323181443-4f499ecaa91d
+	golang.org/x/tools v0.39.1-0.20260527181557-0f52e3809b35
 )
 
 require (

src/cmd/go.sum

@@ -22,7 +22,7 @@ golang.org/x/term v0.38.0 h1:PQ5pkm/rLO6HnxFR7N2lJHOZX6Kez5Y1gDSJla6jo7Q=
 golang.org/x/term v0.38.0/go.mod h1:bSEAKrOT1W+VSu9TSCMtoGEOUcKxOKgl3LE5QEF/xVg=
 golang.org/x/text v0.32.0 h1:ZD01bjUt1FQ9WJ0ClOL5vxgxOI/sVCNgX1YtKwcY0mU=
 golang.org/x/text v0.32.0/go.mod h1:o/rUWzghvpD5TXrTIBuJU77MTaN0ljMWE47kxGJQ7jY=
-golang.org/x/tools v0.39.1-0.20260323181443-4f499ecaa91d h1:d9RYG/Z8xQk+tFy5IyhSwUrt4HhSsqHw/uhwmn1KaJg=
-golang.org/x/tools v0.39.1-0.20260323181443-4f499ecaa91d/go.mod h1:JnefbkDPyD8UU2kI5fuf8ZX4/yUeh9W877ZeBONxUqQ=
+golang.org/x/tools v0.39.1-0.20260527181557-0f52e3809b35 h1:NtO66pjvzVNcFzUfpQKKOKMrSs1SYT4qPtV3xpdv6BE=
+golang.org/x/tools v0.39.1-0.20260527181557-0f52e3809b35/go.mod h1:JnefbkDPyD8UU2kI5fuf8ZX4/yUeh9W877ZeBONxUqQ=
 rsc.io/markdown v0.0.0-20240306144322-0bf8f97ee8ef h1:mqLYrXCXYEZOop9/Dbo6RPX11539nwiCNBb1icVPmw8=
 rsc.io/markdown v0.0.0-20240306144322-0bf8f97ee8ef/go.mod h1:8xcPgWmwlZONN1D9bjxtHEjrUtSEa3fakVF8iaewYKQ=

src/cmd/vendor/modules.txt

@@ -73,7 +73,7 @@ golang.org/x/text/internal/tag
 golang.org/x/text/language
 golang.org/x/text/transform
 golang.org/x/text/unicode/norm
-# golang.org/x/tools v0.39.1-0.20260323181443-4f499ecaa91d
+# golang.org/x/tools v0.39.1-0.20260527181557-0f52e3809b35
 ## explicit; go 1.24.0
 golang.org/x/tools/cmd/bisect
 golang.org/x/tools/cover

src/crypto/internal/fips140/drbg/entropy_fips140.go

@@ -2,24 +2,18 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Entropy generation in FIPS 140-3 mode uses a scratch buffer in the BSS
+// section (see below), which usually doesn't cost much, except on Wasm, due to
+// the way the linear memory works. FIPS 140-3 mode is not supported on Wasm, so
+// we just use a build tag to exclude it. (Could also exclude other platforms
+// that does not support FIPS 140-3 mode, but as the BSS variable doesn't cost
+// much, don't bother.)
+//
 //go:build !wasm
 
-// This file contains reading from from entropy sources in FIPS-140
-// mode. It uses a scratch buffer in the BSS section (see below),
-// which usually doesn't cost much, except on Wasm, due to the way
-// the linear memory works. FIPS-140 mode is not supported on Wasm,
-// so we just use a build tag to exclude it. (Could also exclude other
-// platforms that does not support FIPS-140 mode, but as the BSS
-// variable doesn't cost much, don't bother.)
-
 package drbg
 
-import (
-	entropy "crypto/internal/entropy/v1.0.0"
-	"crypto/internal/sysrand"
-	"sync"
-	"sync/atomic"
-)
+import entropy "crypto/internal/entropy/v1.0.0"
 
 // memory is a scratch buffer that is accessed between samples by the entropy
 // source to expose it to memory access timings.
@@ -50,48 +44,3 @@ func getEntropy() *[SeedSize]byte {
 	}
 	return &seed
 }
-
-// getEntropy is very slow (~500µs), so we don't want it on the hot path.
-// We keep both a persistent DRBG instance and a pool of additional instances.
-// Occasional uses will use drbgInstance, even if the pool was emptied since the
-// last use. Frequent concurrent uses will fill the pool and use it.
-var drbgInstance atomic.Pointer[Counter]
-var drbgPool = sync.Pool{
-	New: func() any {
-		return NewCounter(getEntropy())
-	},
-}
-
-func readFromEntropy(b []byte) {
-	// At every read, 128 random bits from the operating system are mixed as
-	// additional input, to make the output as strong as non-FIPS randomness.
-	// This is not credited as entropy for FIPS purposes, as allowed by Section
-	// 8.7.2: "Note that a DRBG does not rely on additional input to provide
-	// entropy, even though entropy could be provided in the additional input".
-	additionalInput := new([SeedSize]byte)
-	sysrand.Read(additionalInput[:16])
-
-	drbg := drbgInstance.Swap(nil)
-	if drbg == nil {
-		drbg = drbgPool.Get().(*Counter)
-	}
-	defer func() {
-		if !drbgInstance.CompareAndSwap(nil, drbg) {
-			drbgPool.Put(drbg)
-		}
-	}()
-
-	for len(b) > 0 {
-		size := min(len(b), maxRequestSize)
-		if reseedRequired := drbg.Generate(b[:size], additionalInput); reseedRequired {
-			// See SP 800-90A Rev. 1, Section 9.3.1, Steps 6-8, as explained in
-			// Section 9.3.2: if Generate reports a reseed is required, the
-			// additional input is passed to Reseed along with the entropy and
-			// then nulled before the next Generate call.
-			drbg.Reseed(getEntropy(), additionalInput)
-			additionalInput = nil
-			continue
-		}
-		b = b[size:]
-	}
-}

src/crypto/internal/fips140/drbg/entropy_wasm.go

@@ -6,6 +6,6 @@
 
 package drbg
 
-func readFromEntropy(b []byte) {
-	panic("FIPS-140 entropy generation is not supported on Wasm")
+func getEntropy() *[SeedSize]byte {
+	panic("FIPS 140-3 entropy generation is not supported on Wasm")
 }

src/crypto/internal/fips140/drbg/rand.go

@@ -12,8 +12,21 @@ import (
 	"crypto/internal/fips140"
 	"crypto/internal/sysrand"
 	"io"
+	"sync"
+	"sync/atomic"
 )
 
+// getEntropy is very slow (~500µs), so we don't want it on the hot path.
+// We keep both a persistent DRBG instance and a pool of additional instances.
+// Occasional uses will use drbgInstance, even if the pool was emptied since the
+// last use. Frequent concurrent uses will fill the pool and use it.
+var drbgInstance atomic.Pointer[Counter]
+var drbgPool = sync.Pool{
+	New: func() any {
+		return NewCounter(getEntropy())
+	},
+}
+
 // Read fills b with cryptographically secure random bytes. In FIPS mode, it
 // uses an SP 800-90A Rev. 1 Deterministic Random Bit Generator (DRBG).
 // Otherwise, it uses the operating system's random number generator.
@@ -32,7 +45,37 @@ func Read(b []byte) {
 		return
 	}
 
-	readFromEntropy(b)
+	// At every read, 128 random bits from the operating system are mixed as
+	// additional input, to make the output as strong as non-FIPS randomness.
+	// This is not credited as entropy for FIPS purposes, as allowed by Section
+	// 8.7.2: "Note that a DRBG does not rely on additional input to provide
+	// entropy, even though entropy could be provided in the additional input".
+	additionalInput := new([SeedSize]byte)
+	sysrand.Read(additionalInput[:16])
+
+	drbg := drbgInstance.Swap(nil)
+	if drbg == nil {
+		drbg = drbgPool.Get().(*Counter)
+	}
+	defer func() {
+		if !drbgInstance.CompareAndSwap(nil, drbg) {
+			drbgPool.Put(drbg)
+		}
+	}()
+
+	for len(b) > 0 {
+		size := min(len(b), maxRequestSize)
+		if reseedRequired := drbg.Generate(b[:size], additionalInput); reseedRequired {
+			// See SP 800-90A Rev. 1, Section 9.3.1, Steps 6-8, as explained in
+			// Section 9.3.2: if Generate reports a reseed is required, the
+			// additional input is passed to Reseed along with the entropy and
+			// then nulled before the next Generate call.
+			drbg.Reseed(getEntropy(), additionalInput)
+			additionalInput = nil
+			continue
+		}
+		b = b[size:]
+	}
 }
 
 var testingReader io.Reader

src/crypto/x509/verify.go

@@ -110,7 +110,7 @@ func (h HostnameError) Error() string {
 	c := h.Certificate
 	maxNamesIncluded := 100
 
-	if !c.hasSANExtension() && matchHostnames(c.Subject.CommonName, h.Host) {
+	if !c.hasSANExtension() && matchHostnames(c.Subject.CommonName, splitHostname(h.Host)) {
 		return "x509: certificate relies on legacy Common Name field, use SANs instead"
 	}
 
@@ -867,16 +867,14 @@ func matchExactly(hostA, hostB string) bool {
 	return toLowerCaseASCII(hostA) == toLowerCaseASCII(hostB)
 }
 
-func matchHostnames(pattern, host string) bool {
+func matchHostnames(pattern string, hostParts []string) bool {
 	pattern = toLowerCaseASCII(pattern)
-	host = toLowerCaseASCII(strings.TrimSuffix(host, "."))
 
-	if len(pattern) == 0 || len(host) == 0 {
+	if len(pattern) == 0 || len(hostParts) == 0 {
 		return false
 	}
 
 	patternParts := strings.Split(pattern, ".")
-	hostParts := strings.Split(host, ".")
 
 	if len(patternParts) != len(hostParts) {
 		return false
@@ -954,6 +952,7 @@ func (c *Certificate) VerifyHostname(h string) error {
 
 	candidateName := toLowerCaseASCII(h) // Save allocations inside the loop.
 	validCandidateName := validHostnameInput(candidateName)
+	hostParts := splitHostname(candidateName)
 
 	for _, match := range c.DNSNames {
 		// Ideally, we'd only match valid hostnames according to RFC 6125 like
@@ -962,7 +961,7 @@ func (c *Certificate) VerifyHostname(h string) error {
 		// always allow perfect matches, and only apply wildcard and trailing
 		// dot processing to valid hostnames.
 		if validCandidateName && validHostnamePattern(match) {
-			if matchHostnames(match, candidateName) {
+			if matchHostnames(match, hostParts) {
 				return nil
 			}
 		} else {
@@ -975,6 +974,10 @@ func (c *Certificate) VerifyHostname(h string) error {
 	return HostnameError{c, h}
 }
 
+func splitHostname(host string) []string {
+	return strings.Split(toLowerCaseASCII(strings.TrimSuffix(host, ".")), ".")
+}
+
 func checkChainForKeyUsage(chain []*Certificate, keyUsages []ExtKeyUsage) bool {
 	usages := make([]ExtKeyUsage, len(keyUsages))
 	copy(usages, keyUsages)

src/mime/encodedword.go

@@ -275,8 +275,8 @@ func (d *WordDecoder) DecodeHeader(header string) (string, error) {
 		content, err := decode(encoding, text)
 		if err != nil {
 			betweenWords = false
-			buf.WriteString(header[:start+2])
-			header = header[start+2:]
+			buf.WriteString(header[:end])
+			header = header[end:]
 			continue
 		}
 

src/mime/encodedword_test.go

@@ -140,6 +140,10 @@ func TestDecodeHeader(t *testing.T) {
 		{"=?ISO-8859-1?Q?a?=  =?ISO-8859-1?Q?b?=", "ab"},
 		{"=?ISO-8859-1?Q?a?= \r\n\t =?ISO-8859-1?Q?b?=", "ab"},
 		{"=?ISO-8859-1?Q?a_b?=", "a b"},
+		// Undecodable words
+		{"=?UTF-8?b?garbage?= =?UTF-8?b?QW5kcsOp?= =?UTF-8?b?garbage?=", "=?UTF-8?b?garbage?= André =?UTF-8?b?garbage?="},
+		{"=?UTF-8?b?QW5kcsOp", "=?UTF-8?b?QW5kcsOp"},
+		{"=?UTF-8?x?y?=?UTF-8?x?y=?", "=?UTF-8?x?y?=?UTF-8?x?y=?"},
 	}
 
 	for _, test := range tests {

src/net/smtp/smtp_test.go

@@ -695,7 +695,7 @@ func TestHello(t *testing.T) {
 			err = c.Hello("customhost")
 		case 1:
 			err = c.StartTLS(nil)
-			if err.Error() == "502 Not implemented" {
+			if err.Error() == `502 "Not implemented"` {
 				err = nil
 			}
 		case 2:
@@ -953,8 +953,8 @@ func TestAuthFailed(t *testing.T) {
 
 	if err == nil {
 		t.Error("Auth: expected error; got none")
-	} else if err.Error() != "535 Invalid credentials\nplease see www.example.com" {
-		t.Errorf("Auth: got error: %v, want: %s", err, "535 Invalid credentials\nplease see www.example.com")
+	} else if err.Error() != `535 "Invalid credentials\nplease see www.example.com"` {
+		t.Errorf("Auth: got error: %v, want: %s", err, `535 "Invalid credentials\nplease see www.example.com"`)
 	}
 
 	bcmdbuf.Flush()