Update Info


Security update for go1.21

Type: security
Severity: moderate
Issued: 2023-11-09
This update introduces go1.21, including fixes for the following issues:

- go1.21.3 (released 2023-10-10) includes a security fix to the
  net/http package.
  Refs boo#1212475 go1.21 release tracking
  CVE-2023-39325 CVE-2023-44487
  * go#63427 go#63417 boo#1216109 security: fix CVE-2023-39325 CVE-2023-44487 net/http: rapid stream resets can cause excessive work

- go1.21.2 (released 2023-10-05) includes one security fixes to the
  cmd/go package, as well as bug fixes to the compiler, the go
  command, the linker, the runtime, and the runtime/metrics
  Refs boo#1212475 go1.21 release tracking
  * go#63214 go#63211 boo#1215985 security: fix CVE-2023-39323 cmd/go: line directives allows arbitrary execution during build
  * go#62464 runtime: "traceback did not unwind completely"
  * go#62478 runtime/metrics: /gc/scan* metrics return zero
  * go#62505 plugin: variable not initialized properly
  * go#62506 cmd/compile: internal compiler error: InvertFlags should never make it to codegen v100 = InvertFlags v123
  * go#62509 runtime: scheduler change causes Delve's function call injection to fail intermittently
  * go#62537 runtime: "fatal: morestack on g0" with PGO enabled on arm64
  * go#62598 cmd/link: issues with Apple's new linker in Xcode 15 beta
  * go#62668 cmd/compile: slow to compile 17,000 line switch statement?
  * go#62711 cmd/go: TestScript/gotoolchain_path fails if golang.org/dl/go1.21.1 is installed in the user's $PATH

- go1.21.1 (released 2023-09-06) includes four security fixes to
  the cmd/go, crypto/tls, and html/template packages, as well as
  bug fixes to the compiler, the go command, the linker, the
  runtime, and the context, crypto/tls, encoding/gob, encoding/xml,
  go/types, net/http, os, and path/filepath packages.
  Refs boo#1212475 go1.21 release tracking
  CVE-2023-39318 CVE-2023-39319 CVE-2023-39320 CVE-2023-39321 CVE-2023-39322
  * go#62290 go#62266 boo#1215087 security: fix CVE-2023-39321 CVE-2023-39322 crypto/tls: panic when processing partial post-handshake message in QUICConn.HandleData
  * go#62394 go#62198 boo#1215086 security: fix CVE-2023-39320 cmd/go: go.mod toolchain directive allows arbitrary execution
  * go#62396 go#62196 boo#1215084 security: fix CVE-2023-39318 html/template: improper handling of HTML-like comments within script contexts
  * go#62398 go#62197 boo#1215085 security: fix CVE-2023-39319 html/template: improper handling of special tags within script contexts
  * go#61743 go/types: interface.Complete panics for interfaces with duplicate methods
  * go#61781 cmd/compile: internal compiler error: 'f': value .autotmp_1 (nil) incorrectly live at entry
  * go#61818 cmd/go: panic: runtime error: index out of range [-1] in collectDepsErrors
  * go#61821 runtime/internal/wasitest: TestTCPEcho is racy
  * go#61868 path/filepath: Clean on some invalid Windows paths can lose .. components
  * go#61904 net/http: go 1.20.6 host validation breaks setting Host to a unix socket address
  * go#61905 cmd/go: go get/mod tidy panics with internal error: net token acquired but not released
  * go#61909 cmd/compile: internal compiler error: missed typecheck
  * go#61910 os: ReadDir fails on file systems without File ID support on Windows
  * go#61927 cmd/distpack: release archives don't include directory members
  * go#61930 spec, go/types, types2: restore Go 1.20 unification when compiling for Go 1.20
  * go#61932 go/types, types2: index out of range panic in Checker.arguments
  * go#61958 cmd/compile: write barrier code is sometimes preemptible when compiled with -N
  * go#61959 go/types, types2: panic: infinite recursion in unification with go1.21.0
  * go#61964 os: ReadDir(\\.\pipe\) fails with go1.21 on Windows
  * go#61967 crypto/tls: add GODEBUG to control max RSA key size
  * go#61987 runtime: simple programs crash on linux/386 with go1.21 when build with -gcflags='all=-N -l'
  * go#62019 runtime: execution halts with goroutines stuck in runtime.gopark (protocol error E08 during memory read for packet)
  * go#62046 runtime/trace: segfault in runtime.fpTracebackPCs during deferred call after recovering from panic
  * go#62051 encoding/xml: incompatible changes in the Go 1.21.0
  * go#62057 cmd/compile: internal compiler error: 'F': func F, startMem[b1] has different values
  * go#62071 cmd/api: make non-importable
  * go#62140 cmd/link: slice bounds out of range
  * go#62143 hash/crc32: panic on arm64 with go1.21.0 when indexing slice
  * go#62144 cmd/go: locating GOROOT fails when the go command is run from the cross-compiled bin subdirectory
  * go#62154 encoding/gob: panic decoding into local type, received remote type
  * go#62189 context: misuse of sync.Cond in ExampleAfterFunc_cond
  * go#62204 maps: segfault in Clone
  * go#62205 cmd/compile: backward incompatible change in Go 1.21 type inference with channels
  * go#62222 cmd/go: 'go test -o' may fail with ETXTBSY when running the compiled test
  * go#62328 net/http: http client regression building with js/wasm and running on Chrome: net::ERR_H2_OR_QUIC_REQUIRED
  * go#62329 runtime: MADV_HUGEPAGE causes stalls when allocating memory

- go1.21 (released 2023-08-08) is a major release of Go.
  go1.21.x minor releases will be provided through August 2024.
  go1.21 arrives six months after go1.20. Most of its changes are
  in the implementation of the toolchain, runtime, and libraries.
  As always, the release maintains the Go 1 promise of
  compatibility. We expect almost all Go programs to continue to
  compile and run as before.
  Refs boo#1212475 go1.21 release tracking
  * Go 1.21 introduces a small change to the numbering of
    releases. In the past, we used Go 1.N to refer to both the
    overall Go language version and release family as well as the
    first release in that family. Starting in Go 1.21, the first
    release is now Go 1.N.0. Today we are releasing both the Go
    1.21 language and its initial implementation, the Go 1.21.0
    release. These notes refer to "Go 1.21"; tools like go version
    will report "go1.21.0" (until you upgrade to Go 1.21.1). See
    "Go versions" in the "Go Toolchains" documentation for details
    about the new version numbering.
  * Language change: Go 1.21 adds three new built-ins to the
  * Language change: The new functions min and max compute the
    smallest (or largest, for max) value of a fixed number of given
    arguments. See the language spec for details.
  * Language change: The new function clear deletes all elements
    from a map or zeroes all elements of a slice. See the language
    spec for details.
  * Package initialization order is now specified more
    precisely. This may change the behavior of some programs that
    rely on a specific initialization ordering that was not
    expressed by explicit imports. The behavior of such programs
    was not well defined by the spec in past releases. The new rule
    provides an unambiguous definition.
  * Multiple improvements that increase the power and precision of
    type inference have been made.
  * A (possibly partially instantiated generic) function may now be
    called with arguments that are themselves (possibly partially
    instantiated) generic functions.
  * Type inference now also considers methods when a value is
    assigned to an interface: type arguments for type parameters
    used in method signatures may be inferred from the
    corresponding parameter types of matching methods.
  * Similarly, since a type argument must implement all the methods
    of its corresponding constraint, the methods of the type
    argument and constraint are matched which may lead to the
    inference of additional type arguments.
  * If multiple untyped constant arguments of different kinds (such
    as an untyped int and an untyped floating-point constant) are
    passed to parameters with the same (not otherwise specified)
    type parameter type, instead of an error, now type inference
    determines the type using the same approach as an operator with
    untyped constant operands. This change brings the types
    inferred from untyped constant arguments in line with the types
    of constant expressions.
  * Type inference is now precise when matching corresponding types
    in assignments
  * The description of type inference in the language spec has been
  * Go 1.21 includes a preview of a language change we are
    considering for a future version of Go: making for loop
    variables per-iteration instead of per-loop, to avoid
    accidental sharing bugs. For details about how to try that
    language change, see the LoopvarExperiment wiki page.
  * Go 1.21 now defines that if a goroutine is panicking and
    recover was called directly by a deferred function, the return
    value of recover is guaranteed not to be nil. To ensure this,
    calling panic with a nil interface value (or an untyped nil)
    causes a run-time panic of type *runtime.PanicNilError.
    To support programs written for older versions of Go, nil
    panics can be re-enabled by setting GODEBUG=panicnil=1. This
    setting is enabled automatically when compiling a program whose
    main package is in a module with that declares go 1.20 or
  * Go 1.21 adds improved support for backwards compatibility and
    forwards compatibility in the Go toolchain.
  * To improve backwards compatibility, Go 1.21 formalizes Go's use
    of the GODEBUG environment variable to control the default
    behavior for changes that are non-breaking according to the
    compatibility policy but nonetheless may cause existing
    programs to break. (For example, programs that depend on buggy
    behavior may break when a bug is fixed, but bug fixes are not
    considered breaking changes.) When Go must make this kind of
    behavior change, it now chooses between the old and new
    behavior based on the go line in the workspace's go.work file
    or else the main module's go.mod file. Upgrading to a new Go
    toolchain but leaving the go line set to its original (older)
    Go version preserves the behavior of the older toolchain. With
    this compatibility support, the latest Go toolchain should
    always be the best, most secure, implementation of an older
    version of Go. See "Go, Backwards Compatibility, and GODEBUG"
    for details.
  * To improve forwards compatibility, Go 1.21 now reads the go
    line in a go.work or go.mod file as a strict minimum
    requirement: go 1.21.0 means that the workspace or module
    cannot be used with Go 1.20 or with Go 1.21rc1. This allows
    projects that depend on fixes made in later versions of Go to
    ensure that they are not used with earlier versions. It also
    gives better error reporting for projects that make use of new
    Go features: when the problem is that a newer Go version is
    needed, that problem is reported clearly, instead of attempting
    to build the code and instead printing errors about unresolved
    imports or syntax errors.
  * To make these new stricter version requirements easier to
    manage, the go command can now invoke not just the toolchain
    bundled in its own release but also other Go toolchain versions
    found in the PATH or downloaded on demand. If a go.mod or
    go.work go line declares a minimum requirement on a newer
    version of Go, the go command will find and run that version
    automatically. The new toolchain directive sets a suggested
    minimum toolchain to use, which may be newer than the strict go
    minimum. See "Go Toolchains" for details.
  * go command: The -pgo build flag now defaults to -pgo=auto, and
    the restriction of specifying a single main package on the
    command line is now removed. If a file named default.pgo is
    present in the main package's directory, the go command will
    use it to enable profile-guided optimization for building the
    corresponding program.
  * go command: The -C dir flag must now be the first flag on the
    command-line when used.
  * go command: The new go test option -fullpath prints full path
    names in test log messages, rather than just base names.
  * go command: The go test -c flag now supports writing test
    binaries for multiple packages, each to pkg.test where pkg is
    the package name. It is an error if more than one test package
    being compiled has a given package name.]
  * go command: The go test -o flag now accepts a directory
    argument, in which case test binaries are written to that
    directory instead of the current directory.
  * cgo: In files that import "C", the Go toolchain now correctly
    reports errors for attempts to declare Go methods on C types.
  * runtime: When printing very deep stacks, the runtime now prints
    the first 50 (innermost) frames followed by the bottom 50
    (outermost) frames, rather than just printing the first 100
    frames. This makes it easier to see how deeply recursive stacks
    started, and is especially valuable for debugging stack
  * runtime: On Linux platforms that support transparent huge
    pages, the Go runtime now manages which parts of the heap may
    be backed by huge pages more explicitly. This leads to better
    utilization of memory: small heaps should see less memory used
    (up to 50% in pathological cases) while large heaps should see
    fewer broken huge pages for dense parts of the heap, improving
    CPU usage and latency by up to 1%.
  * runtime: As a result of runtime-internal garbage collection
    tuning, applications may see up to a 40% reduction in
    application tail latency and a small decrease in memory
    use. Some applications may also observe a small loss in
    throughput. The memory use decrease should be proportional to
    the loss in throughput, such that the previous release's
    throughput/memory tradeoff may be recovered (with little change
    to latency) by increasing GOGC and/or GOMEMLIMIT slightly.
  * runtime: Calls from C to Go on threads created in C require
    some setup to prepare for Go execution. On Unix platforms, this
    setup is now preserved across multiple calls from the same
    thread. This significantly reduces the overhead of subsequent C
    to Go calls from ~1-3 microseconds per call to ~100-200
    nanoseconds per call.
  * compiler: Profile-guide optimization (PGO), added as a preview
    in Go 1.20, is now ready for general use. PGO enables
    additional optimizations on code identified as hot by profiles
    of production workloads. As mentioned in the Go command
    section, PGO is enabled by default for binaries that contain a
    default.pgo profile in the main package directory. Performance
    improvements vary depending on application behavior, with most
    programs from a representative set of Go programs seeing
    between 2 and 7% improvement from enabling PGO. See the PGO
    user guide for detailed documentation.
  * compiler: PGO builds can now devirtualize some interface method
    calls, adding a concrete call to the most common callee. This
    enables further optimization, such as inlining the callee.
  * compiler: Go 1.21 improves build speed by up to 6%, largely
    thanks to building the compiler itself with PGO.
  * assembler: On amd64, frameless nosplit assembly functions are
    no longer automatically marked as NOFRAME. Instead, the NOFRAME
    attribute must be explicitly specified if desired, which is
    already the behavior on other architectures supporting frame
    pointers. With this, the runtime now maintains the frame
    pointers for stack transitions.
  * assembler: The verifier that checks for incorrect uses of R15
    when dynamic linking on amd64 has been improved.
  * linker: On windows/amd64, the linker (with help from the
    compiler) now emits SEH unwinding data by default, which
    improves the integration of Go applications with Windows
    debuggers and other tools.
  * linker: In Go 1.21 the linker (with help from the compiler) is
    now capable of deleting dead (unreferenced) global map
    variables, if the number of entries in the variable initializer
    is sufficiently large, and if the initializer expressions are
    side-effect free.
  * core library: The new log/slog package provides structured
    logging with levels. Structured logging emits key-value pairs
    to enable fast, accurate processing of large amounts of log
    data. The package supports integration with popular log
    analysis tools and services.
  * core library: The new testing/slogtest package can help to
    validate slog.Handler implementations.
  * core library: The new slices package provides many common
    operations on slices, using generic functions that work with
    slices of any element type.
  * core library: The new maps package provides several common
    operations on maps, using generic functions that work with maps
    of any key or element type.
  * core library: The new cmp package defines the type constraint
    Ordered and two new generic functions Less and Compare that are
    useful with ordered types.
  * Minor changes to the library: As always, there are various
    minor changes and updates to the library, made with the Go 1
    promise of compatibility in mind. There are also various
    performance improvements, not enumerated here.
  * archive/tar: The implementation of the io/fs.FileInfo interface
    returned by Header.FileInfo now implements a String method that
    calls io/fs.FormatFileInfo.
  * archive/zip: The implementation of the io/fs.FileInfo interface
    returned by FileHeader.FileInfo now implements a String method
    that calls io/fs.FormatFileInfo.
  * archive/zip: The implementation of the io/fs.DirEntry interface
    returned by the io/fs.ReadDirFile.ReadDir method of the
    io/fs.File returned by Reader.Open now implements a String
    method that calls io/fs.FormatDirEntry.
  * bytes: The Buffer type has two new methods: Available and
    AvailableBuffer. These may be used along with the Write method
    to append directly to the Buffer.
  * context: The new WithoutCancel function returns a copy of a
    context that is not canceled when the original context is
  * context: The new WithDeadlineCause and WithTimeoutCause
    functions provide a way to set a context cancellation cause
    when a deadline or timer expires. The cause may be retrieved
    with the Cause function.
  * context: The new AfterFunc function registers a function to run
    after a context has been cancelled.
  * context: An optimization means that the results of calling
    Background and TODO and converting them to a shared type can be
    considered equal. In previous releases they were always
    different. Comparing Context values for equality has never been
    well-defined, so this is not considered to be an incompatible
  * crypto/ecdsa: PublicKey.Equal and PrivateKey.Equal now execute
    in constant time.
  * crypto/elliptic: All of the Curve methods have been deprecated,
    along with GenerateKey, Marshal, and Unmarshal. For ECDH
    operations, the new crypto/ecdh package should be used
    instead. For lower-level operations, use third-party modules
    such as filippo.io/nistec.
  * crypto/rand: The crypto/rand package now uses the getrandom
    system call on NetBSD 10.0 and later.
  * crypto/rsa: The performance of private RSA operations
    (decryption and signing) is now better than Go 1.19 for
    GOARCH=amd64 and GOARCH=arm64. It had regressed in Go 1.20.
  * crypto/rsa: Due to the addition of private fields to
    PrecomputedValues, PrivateKey.Precompute must be called for
    optimal performance even if deserializing (for example from
    JSON) a previously-precomputed private key.
  * crypto/rsa: PublicKey.Equal and PrivateKey.Equal now execute in
    constant time.
  * crypto/rsa: The GenerateMultiPrimeKey function and the
    PrecomputedValues.CRTValues field have been
    deprecated. PrecomputedValues.CRTValues will still be populated
    when PrivateKey.Precompute is called, but the values will not
    be used during decryption operations.
  * crypto/sha256: SHA-224 and SHA-256 operations now use native
    instructions when available when GOARCH=amd64, providing a
    performance improvement on the order of 3-4x.
  * crypto/tls: Servers now skip verifying client certificates
    (including not running Config.VerifyPeerCertificate) for
    resumed connections, besides checking the expiration time. This
    makes session tickets larger when client certificates are in
    use. Clients were already skipping verification on resumption,
    but now check the expiration time even if
    Config.InsecureSkipVerify is set.
  * crypto/tls: Applications can now control the content of session
  * crypto/tls: The new SessionState type describes a resumable
  * crypto/tls: The SessionState.Bytes method and ParseSessionState
    function serialize and deserialize a SessionState.
  * crypto/tls: The Config.WrapSession and Config.UnwrapSession
    hooks convert a SessionState to and from a ticket on the server
  * crypto/tls: The Config.EncryptTicket and Config.DecryptTicket
    methods provide a default implementation of WrapSession and
  * crypto/tls: The ClientSessionState.ResumptionState method and
    NewResumptionState function may be used by a ClientSessionCache
    implementation to store and resume sessions on the client side.
  * crypto/tls: To reduce the potential for session tickets to be
    used as a tracking mechanism across connections, the server now
    issues new tickets on every resumption (if they are supported
    and not disabled) and tickets don't bear an identifier for the
    key that encrypted them anymore. If passing a large number of
    keys to Conn.SetSessionTicketKeys, this might lead to a
    noticeable performance cost.
  * crypto/tls: Both clients and servers now implement the Extended
    Master Secret extension (RFC 7627). The deprecation of
    ConnectionState.TLSUnique has been reverted, and is now set for
    resumed connections that support Extended Master Secret.
  * crypto/tls: The new QUICConn type provides support for QUIC
    implementations, including 0-RTT support. Note that this is not
    itself a QUIC implementation, and 0-RTT is still not supported
    in TLS.
  * crypto/tls: The new VersionName function returns the name for a
    TLS version number.
  * crypto/tls: The TLS alert codes sent from the server for client
    authentication failures have been improved. Previously, these
    failures always resulted in a "bad certificate" alert. Now,
    certain failures will result in more appropriate alert codes,
    as defined by RFC 5246 and RFC 8446:
  * crypto/tls: For TLS 1.3 connections, if the server is
    configured to require client authentication using
    RequireAnyClientCert or RequireAndVerifyClientCert, and the
    client does not provide any certificate, the server will now
    return the "certificate required" alert.
  * crypto/tls: If the client provides a certificate that is not
    signed by the set of trusted certificate authorities configured
    on the server, the server will return the "unknown certificate
    authority" alert.
  * crypto/tls: If the client provides a certificate that is either
    expired or not yet valid, the server will return the "expired
    certificate" alert.
  * crypto/tls: In all other scenarios related to client
    authentication failures, the server still returns "bad
  * crypto/x509: RevocationList.RevokedCertificates has been
    deprecated and replaced with the new RevokedCertificateEntries
    field, which is a slice of RevocationListEntry.
    RevocationListEntry contains all of the fields in
    pkix.RevokedCertificate, as well as the revocation reason code.
  * crypto/x509: Name constraints are now correctly enforced on
    non-leaf certificates, and not on the certificates where they
    are expressed.
  * debug/elf: The new File.DynValue method may be used to retrieve
    the numeric values listed with a given dynamic tag.
  * debug/elf: The constant flags permitted in a DT_FLAGS_1 dynamic
    tag are now defined with type DynFlag1. These tags have names
    starting with DF_1.
  * debug/elf: The package now defines the constant COMPRESS_ZSTD.
  * debug/elf: The package now defines the constant
  * debug/pe: Attempts to read from a section containing
    uninitialized data using Section.Data or the reader returned by
    Section.Open now return an error.
  * embed: The io/fs.File returned by FS.Open now has a ReadAt
    method that implements io.ReaderAt.
  * embed: Calling FS.Open.Stat will return a type that now
    implements a String method that calls io/fs.FormatFileInfo.
  * errors: The new ErrUnsupported error provides a standardized
    way to indicate that a requested operation may not be performed
    because it is unsupported. For example, a call to os.Link when
    using a file system that does not support hard links.
  * flag: The new BoolFunc function and FlagSet.BoolFunc method
    define a flag that does not require an argument and calls a
    function when the flag is used. This is similar to Func but for
    a boolean flag.
  * flag: A flag definition (via Bool, BoolVar, Int, IntVar, etc.)
    will panic if Set has already been called on a flag with the
    same name. This change is intended to detect cases where
    changes in initialization order cause flag operations to occur
    in a different order than expected. In many cases the fix to
    this problem is to introduce a explicit package dependence to
    correctly order the definition before any Set operations.
  * go/ast: The new IsGenerated predicate reports whether a file
    syntax tree contains the special comment that conventionally
    indicates that the file was generated by a tool.
  * go/ast: The new File.GoVersion field records the minimum Go
    version required by any //go:build or // +build directives.
  * go/build: The package now parses build directives (comments
    that start with //go:) in file headers (before the package
    declaration). These directives are available in the new Package
    fields Directives, TestDirectives, and XTestDirectives.
  * go/build/constraint: The new GoVersion function returns the
    minimum Go version implied by a build expression.
  * go/token: The new File.Lines method returns the file's
    line-number table in the same form as accepted by
  * go/types: The new Package.GoVersion method returns the Go
    language version used to check the package.
  * hash/maphash: The hash/maphash package now has a pure Go
    implementation, selectable with the purego build tag.
  * html/template: The new error ErrJSTemplate is returned when an
    action appears in a JavaScript template literal. Previously an
    unexported error was returned.
  * io/fs: The new FormatFileInfo function returns a formatted
    version of a FileInfo. The new FormatDirEntry function returns
    a formatted version of a DirEntry. The implementation of
    DirEntry returned by ReadDir now implements a String method
    that calls FormatDirEntry, and the same is true for the
    DirEntry value passed to WalkDirFunc.
  * math/big: The new Int.Float64 method returns the nearest
    floating-point value to a multi-precision integer, along with
    an indication of any rounding that occurred.
  * net: On Linux, the net package can now use Multipath TCP when
    the kernel supports it. It is not used by default. To use
    Multipath TCP when available on a client, call the
    Dialer.SetMultipathTCP method before calling the Dialer.Dial or
    Dialer.DialContext methods. To use Multipath TCP when available
    on a server, call the ListenConfig.SetMultipathTCP method
    before calling the ListenConfig.Listen method. Specify the
    network as "tcp" or "tcp4" or "tcp6" as usual. If Multipath TCP
    is not supported by the kernel or the remote host, the
    connection will silently fall back to TCP. To test whether a
    particular connection is using Multipath TCP, use the
    TCPConn.MultipathTCP method.
  * net: In a future Go release we may enable Multipath TCP by
    default on systems that support it.
  * net/http: The new ResponseController.EnableFullDuplex method
    allows server handlers to concurrently read from an HTTP/1
    request body while writing the response. Normally, the HTTP/1
    server automatically consumes any remaining request body before
    starting to write the response, to avoid deadlocking clients
    which attempt to write a complete request before reading the
    response. The EnableFullDuplex method disables this behavior.
  * net/http: The new ErrSchemeMismatch error is returned by Client
    and Transport when the server responds to an HTTPS request with
    an HTTP response.
  * net/http: The net/http package now supports
    errors.ErrUnsupported, in that the expression
    errors.Is(http.ErrNotSupported, errors.ErrUnsupported) will
    return true.
  * os: Programs may now pass an empty time.Time value to the
    Chtimes function to leave either the access time or the
    modification time unchanged.
  * os: On Windows the File.Chdir method now changes the current
    directory to the file, rather than always returning an error.
  * os: On Unix systems, if a non-blocking descriptor is passed to
    NewFile, calling the File.Fd method will now return a
    non-blocking descriptor. Previously the descriptor was
    converted to blocking mode.
  * os: On Windows calling Truncate on a non-existent file used to
    create an empty file. It now returns an error indicating that
    the file does not exist.
  * os: On Windows calling TempDir now uses GetTempPath2W when
    available, instead of GetTempPathW. The new behavior is a
    security hardening measure that prevents temporary files
    created by processes running as SYSTEM to be accessed by
    non-SYSTEM processes.
  * os: On Windows the os package now supports working with files
    whose names, stored as UTF-16, can't be represented as valid
  * os: On Windows Lstat now resolves symbolic links for paths
    ending with a path separator, consistent with its behavior on
    POSIX platforms.
  * os: The implementation of the io/fs.DirEntry interface returned
    by the ReadDir function and the File.ReadDir method now
    implements a String method that calls io/fs.FormatDirEntry.
  * os: The implementation of the io/fs.FS interface returned by
    the DirFS function now implements the io/fs.ReadFileFS and the
    io/fs.ReadDirFS interfaces.
  * path/filepath: The implementation of the io/fs.DirEntry
    interface passed to the function argument of WalkDir now
    implements a String method that calls io/fs.FormatDirEntry.
  * reflect: In Go 1.21, ValueOf no longer forces its argument to
    be allocated on the heap, allowing a Value's content to be
    allocated on the stack. Most operations on a Value also allow
    the underlying value to be stack allocated.
  * reflect: The new Value method Value.Clear clears the contents
    of a map or zeros the contents of a slice. This corresponds to
    the new clear built-in added to the language.
  * reflect: The SliceHeader and StringHeader types are now
    deprecated. In new code prefer unsafe.Slice, unsafe.SliceData,
    unsafe.String, or unsafe.StringData.
  * regexp: Regexp now defines MarshalText and UnmarshalText
    methods. These implement encoding.TextMarshaler and
    encoding.TextUnmarshaler and will be used by packages such as
  * runtime: Textual stack traces produced by Go programs, such as
    those produced when crashing, calling runtime.Stack, or
    collecting a goroutine profile with debug=2, now include the
    IDs of the goroutines that created each goroutine in the stack
  * runtime: Crashing Go applications can now opt-in to Windows
    Error Reporting (WER) by setting the environment variable
    GOTRACEBACK=wer or calling debug.SetTraceback("wer") before the
    crash. Other than enabling WER, the runtime will behave as with
    GOTRACEBACK=crash. On non-Windows systems, GOTRACEBACK=wer is
  * runtime: GODEBUG=cgocheck=2, a thorough checker of cgo pointer
    passing rules, is no longer available as a debug
    option. Instead, it is available as an experiment using
    GOEXPERIMENT=cgocheck2. In particular this means that this mode
    has to be selected at build time instead of startup time.
  * runtime: GODEBUG=cgocheck=1 is still available (and is still
    the default).
  * runtime: A new type Pinner has been added to the runtime
    package. Pinners may be used to "pin" Go memory such that it
    may be used more freely by non-Go code. For instance, passing
    Go values that reference pinned Go memory to C code is now
    allowed. Previously, passing any such nested reference was
    disallowed by the cgo pointer passing rules. See the docs for
    more details.
  * runtime/metrics: A few previously-internal GC metrics, such as
    live heap size, are now available. GOGC and GOMEMLIMIT are also
    now available as metrics.
  * runtime/trace: Collecting traces on amd64 and arm64 now incurs
    a substantially smaller CPU cost: up to a 10x improvement over
    the previous release.
  * runtime/trace: Traces now contain explicit stop-the-world
    events for every reason the Go runtime might stop-the-world,
    not just garbage collection.
  * sync: The new OnceFunc, OnceValue, and OnceValues functions
    capture a common use of Once to lazily initialize a value on
    first use.
  * syscall: On Windows the Fchdir function now changes the current
    directory to its argument, rather than always returning an
  * syscall: On FreeBSD SysProcAttr has a new field Jail that may
    be used to put the newly created process in a jailed
  * syscall: On Windows the syscall package now supports working
    with files whose names, stored as UTF-16, can't be represented
    as valid UTF-8. The UTF16ToString and UTF16FromString functions
    now convert between UTF-16 data and WTF-8 strings. This is
    backward compatible as WTF-8 is a superset of the UTF-8 format
    that was used in earlier releases.
  * syscall: Several error values match the new
    errors.ErrUnsupported, such that errors.Is(err,
    errors.ErrUnsupported) returns true.
    EPLAN9 (Plan 9 only)
    ERROR_NOT_SUPPORTED (Windows only)
    EWINDOWS (Windows only)
  * testing: The new -test.fullpath option will print full path
    names in test log messages, rather than just base names.
  * testing: The new Testing function reports whether the program
    is a test created by go test.
  * testing/fstest: Calling Open.Stat will return a type that now
    implements a String method that calls io/fs.FormatFileInfo.
  * unicode: The unicode package and associated support throughout
    the system has been upgraded to Unicode 15.0.0.
  * Darwin port: As announced in the Go 1.20 release notes, Go 1.21
    requires macOS 10.15 Catalina or later; support for previous
    versions has been discontinued.
  * Windows port: As announced in the Go 1.20 release notes, Go
    1.21 requires at least Windows 10 or Windows Server 2016;
    support for previous versions has been discontinued.
  * WebAssembly port: The new go:wasmimport directive can now be
    used in Go programs to import functions from the WebAssembly
  * WebAssembly port: The Go scheduler now interacts much more
    efficiently with the JavaScript event loop, especially in
    applications that block frequently on asynchronous events.
  * WebAssembly System Interface port: Go 1.21 adds an experimental
    port to the WebAssembly System Interface (WASI), Preview 1
    (GOOS=wasip1, GOARCH=wasm).
  * WebAssembly System Interface port: As a result of the addition
    of the new GOOS value "wasip1", Go files named *_wasip1.go will
    now be ignored by Go tools except when that GOOS value is being
    used. If you have existing filenames matching that pattern, you
    will need to rename them.
  * ppc64/ppc64le port: On Linux, GOPPC64=power10 now generates
    PC-relative instructions, prefixed instructions, and other new
    Power10 instructions. On AIX, GOPPC64=power10 generates Power10
    instructions, but does not generate PC-relative instructions.
  * ppc64/ppc64le port: When building position-independent binaries
    for GOPPC64=power10 GOOS=linux GOARCH=ppc64le, users can expect
    reduced binary sizes in most cases, in some cases
    3.5%. Position-independent binaries are built for ppc64le with
    the following -buildmode values: c-archive, c-shared, shared,
    pie, plugin.
  * loong64 port: The linux/loong64 port now supports
    -buildmode=c-archive, -buildmode=c-shared and -buildmode=pie.



  • go-1.21-41.1
  • go1.21-1.21.3-2.1