GNU C Library NEWS -- history of user-visible changes.
Copyright (C) 1992-2021 Free Software Foundation, Inc.
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Version 2.33

Major new features:

* The dynamic linker accepts the --list-tunables argument which prints
  all the supported tunables.  This option is disable if glibc is
  configured with tunables disabled (--enable-tunables=no).

* The dynamic linker accepts the --argv0 argument and provides opportunity
  to change argv[0] string.

* The dynamic linker loads optimized implementations of shared objects
  from subdirectories under the glibc-hwcaps directory on the library
  search path if the system's capabilities meet the requirements for
  that subdirectory.  Initially supported subdirectories include
  "power9" and "power10" for the powerpc64le-linux-gnu architecture,
  "z13", "z14", "z15" for s390x-linux-gnu, and "x86-64-v2", "x86-64-v3",
  "x86-64-v4" for x86_64-linux-gnu.  In the x86_64-linux-gnu case, the
  subdirectory names correspond to the vendor-independent x86-64
  microarchitecture levels defined in the x86-64 psABI supplement.

* The new --help option of the dynamic linker provides usage and
  information and library search path diagnostics.

* The mallinfo2 function is added to report statistics as per mallinfo,
  but with larger field widths to accurately report values that are
  larger than fit in an integer.

* Add <sys/platform/x86.h> to provide query macros for x86 CPU features.

* Support for the RISC-V ISA running on Linux has been expanded to run on
  32-bit hardware.  This is supported for the following ISA and ABI pairs:

    - rv32imac ilp32
    - rv32imafdc ilp32
    - rv32imafdc ilp32d

  The 32-bit RISC-V port requires at least Linux 5.4, GCC 7.1 and binutils
  2.28.

* A new fortification level _FORTIFY_SOURCE=3 is available.  At this level,
  glibc may use additional checks that may have an additional performance
  overhead.  At present these checks are available only on LLVM 9 and later.
  The latest GCC available at this time (10.2) does not support this level of
  fortification.

Deprecated and removed features, and other changes affecting compatibility:

* The mallinfo function is marked deprecated.  Callers should call
  mallinfo2 instead.

* When dlopen is used in statically linked programs, alternative library
  implementations from HWCAP subdirectories are no longer loaded.
  Instead, the default implementation is used.

* The deprecated <sys/vtimes.h> header and the function vtimes have been
  removed.  To support old binaries, the vtimes function continues to exist
  as a compatibility symbol.  Applications should use the getrlimit or
  prlimit.

* Following a change in the tzdata 2018a release upstream, the zdump
  program is now installed in the /usr/bin subdirectory.  Previously,
  the /usr/sbin subdirectory was used.

* On s390(x), the type float_t is now derived from the macro
  __FLT_EVAL_METHOD__ that is defined by the compiler, instead of being
  hardcoded to double.  This does not affect the ABI of any libraries
  that are part of the GNU C Library, but may affect the ABI of other
  libraries that use this type in their interfaces.  The new definition
  improves consistency with compiler behavior in many scenarios.

* A future version of glibc will stop loading shared objects from the
  "tls" subdirectories on the library search path, the subdirectory that
  corresponds to the AT_PLATFORM system name, and also stop employing
  the legacy AT_HWCAP search mechanism.  Applications should switch to
  the new glibc-hwcaps mechanism instead; if they do not do that, only
  the baseline version (directly from the search path directory) will be
  loaded.

Changes to build and runtime requirements:

* On Linux, the system administrator needs to configure /dev/pts with
  the intended access modes for pseudo-terminals.  glibc no longer
  attemps to adjust permissions of terminal devices.  The previous glibc
  defaults ("tty" group, user read/write and group write) already
  corresponded to what most systems used, so that grantpt did not
  perform any adjustments.

* On Linux, the posix_openpt and getpt functions no longer attempt to
  use legacy (BSD) pseudo-terminals and assume that if /dev/ptmx exists
  (and pseudo-terminals are supported), a devpts file system is mounted
  on /dev/pts.  Current systems already meet these requirements.

* s390x requires GCC 7.1 or newer.  See gcc Bug 98269.

Security related changes:

  CVE-2021-3326: An assertion failure during conversion from the
  ISO-20220-JP-3 character set using the iconv function has been fixed.
  This assertion was triggered by certain valid inputs in which the
  converted output contains a combined sequence of two wide characters
  crossing a buffer boundary.  Reported by Tavis Ormandy.

  CVE-2020-27618: An infinite loop has been fixed in the iconv program when
  invoked with input containing redundant shift sequences in the IBM1364,
  IBM1371, IBM1388, IBM1390, or IBM1399 character sets.

  CVE-2020-29562: An assertion failure has been fixed in the iconv function
  when invoked with UCS4 input containing an invalid character.

  CVE-2019-25013: A buffer overflow has been fixed in the iconv function when
  invoked with EUC-KR input containing invalid multibyte input sequences.

  CVE-2021-33574: The mq_notify function has a potential use-after-free
  issue when using a notification type of SIGEV_THREAD and a thread
  attribute with a non-default affinity mask.

  CVE-2021-3998: Passing a path longer than PATH_MAX to the realpath
  function could result in a memory leak and potential access of
  uninitialized memory.  Reported by Qualys.

  CVE-2021-3999: Passing a buffer of size exactly 1 byte to the getcwd
  function may result in an off-by-one buffer underflow and overflow
  when the current working directory is longer than PATH_MAX and also
  corresponds to the / directory through an unprivileged mount
  namespace.  Reported by Qualys.

The following bugs are resolved with this release:

  [10635] libc: realpath portability patches
  [16124] dynamic-link: ld.so should allow to change argv[0]
  [17924] malloc: 'free' should not set errno
  [18683] libc: Linux faccessat implementation can incorrectly ignore
    AT_EACCESS
  [22899] libc: Use 64-bit readdir() in generic POSIX getcwd()
  [23249] libc: Epyc and other current AMD CPUs do not select the
    "haswell" platform subdirectory
  [24080] dynamic-link: Definition of "haswell" platform is inconsistent
    with GCC
  [24202] libc: m68k setjmp() saves incorrect 'a5' register in --enable-
    stack-protector=all
  [24941] libc: Make grantpt usable after multi-threaded fork in more
    cases
  [24970] libc: realpath mishandles EOVERFLOW; stat not needed anyway
  [24973] locale: iconv encounters segmentation fault when converting
    0x00 0xfe in EUC-KR to UTF-8 (CVE-2019-25013)
  [25399] string: undefined reference to `__warn_memset_zero_len' when
    changing gnuc version
  [25859] libc: glibc parser for /sys/devices/system/cpu/online is
    incorrect
  [25938] dynamic-link: ld.so.cache should store meaning of hwcap mask
    bits
  [25971] libc: s390 bits/hwcap.h out of sync with kernel
  [26053] libc: unlockpt fails with ENOTTY for non-ptmx descriptors
  [26100] libc: Race in syslog(3) with regards to tag printing.
  [26124] libc: Export <cpu-features.h>
  [26130] nscd: Inconsistent nscd cache during pruning
  [26203] libc: GLRO(dl_x86_cpu_features) may not be intialized
  [26224] locale: iconv hangs when converting some invalid inputs from
    several IBM character sets (CVE-2020-27618)
  [26341] libc: realpath cyclically call __alloca(path_max) to consume
    too much stack space
  [26343] manual: invalid documented return type for strerrorname_np(),
    strerrordesc_np(), sigdescr_np(), sigabbrev_np()
  [26376] libc: Namespace violation in stdio.h and sys/stat.h if build
    with optimization.
  [26383] locale: bind_textdomain_codeset doesn't accept //TRANSLIT
    anymore
  [26394] time: [2.33 Regression] FAIL: nptl/tst-join14
  [26534] math: libm.so 2.32 SIGILL in pow() due to FMA4 instruction on
    non-FMA4 system
  [26552] dynamic-link: CPU_FEATURE_USABLE_P should be more conservative
  [26553] libc: mtx_init allows type set to "mtx_recursive" only
  [26555] string: strerrorname_np does not return the documented value
  [26592] libc: pointer arithmetic overflows in realpath
  [26600] network: Transaction ID collisions cause slow DNS lookups in
    getaddrinfo
  [26606] libc: [2.33 Regression] pselect is broken on x32
  [26615] libc: powerpc: libc segfaults when LD_PRELOADed with libgcc
  [26620] glob: fnmatch with collating symbols results in segmentation
    fault
  [26625] libc: [2.33 Regression] CET is disabled
  [26636] libc: 32-bit shmctl(IPC_INFO) crashes when shminfo struct is
    at the end of a memory mapping
  [26637] libc: semctl SEM_STAT_ANY fails to pass the buffer specified
    by the caller to the kernel
  [26639] libc: msgctl IPC_INFO and MSG_INFO return garbage
  [26647] build: [-Werror=array-parameter=] due to different
    declarations for __sigsetjmp
  [26648] libc: mkstemp is likely to fail on systems with non-stricly-
    monotonic clocks
  [26649] stdio: printf should handle non-normal x86 long double numbers
    gracefully (CVE-2020-29573)
  [26686] build: -Warray-parameter instances building with GCC 11
  [26687] build: -Warray-bounds instances building with GCC 11
  [26690] stdio: Aliasing violation in __vfscanf_internal
  [26691] nptl: Use a minimum guard size of 64 KiB on aarch64
  [26726] build: GCC warning calling new_composite_name with an array of
    one element
  [26736] libc: FAIL: misc/tst-sysvshm-linux
  [26737] libc: Random FAIL: rt/tst-shm
  [26791] libc: Missing O_CLOEXEC in sysconf.c
  [26798] dynamic-link: aarch64: variant PCS symbols may be incorrectly
    lazy bound
  [26801] nptl: pthread_mutex_clocklock with CLOCK_MONOTONIC can fail on
    PI mutexes
  [26818] string: aarch64: string tests may run ifunc variants that are
    not safe
  [26821] libc: Memory leak test failures on Fedora 33
  [26824] libc: FAIL: elf/tst-cpu-features-supports with recent trunk:
    FSGSBASE/LM/RDRAND check failure
  [26833] time: adjtime() with delta == NULL segfaults on armv7 32bit
    platform
  [26853] libc: aarch64: Missing unwind information in statically linked
    startup code
  [26923] locale: Assertion failure in iconv when converting invalid
    UCS4 (CVE-2020-29562)
  [26926] dynamic-link: aarch64: library dependencies are not bti
    protected
  [26932] libc: sh: Multiple floating point functions defined as stubs
    only since 2.31
  [26964] nptl: pthread_mutex_timedlock returning EAGAIN after futex is
    locked
  [26988] dynamic-link: aarch64: BTI mprotect address is not page
    aligned
  [27002] build: libc_freeres_fn build failure with GCC 11
  [27004] dynamic-link: ld.so is miscompiled by GCC 11
  [27008] dynamic-link: ld.so.cache should have endianness markup
  [27042] libc: [alpha] anonymous union in struct stat confuses
    detection logic
  [27053] libc: Conformance regression in system(3) (and probably also
    pclose(3))
  [27072] dynamic-link: static pie ifunc resolvers run before hwcap is
    setup
  [27077] network: Do not reload /etc/nsswitch.conf from chroot
  [27083] libc: Unsafe unbounded alloca in addmntent
  [27104] dynamic-link: The COMMON_CPUID_INDEX_MAX handshake does not
    work
  [27130] string: "rep movsb" performance issue
  [27150] libc: alpha: wait4() is unavailable in static linking
  [27177] dynamic-link:
    GLIBC_TUNABLES=glibc.cpu.x86_ibt=on:glibc.cpu.x86_shstk=on doesn't
    work
  [27222] dynamic-link: Incorrect sysdeps/x86/tst-cpu-features-cpuinfo.c
  [27237] malloc: deadlock in malloc/tst-malloc-stats-cancellation
  [27256] locale: Assertion failure in ISO-2022-JP-3 gconv module
    related to combining characters (CVE-2021-3326)


Version 2.32

Major new features:

* Unicode 13.0.0 Support: Character encoding, character type info, and
  transliteration tables are all updated to Unicode 13.0.0, using
  generator scripts contributed by Mike FABIAN (Red Hat).

* New locale added: ckb_IQ (Kurdish/Sorani spoken in Iraq)

* Support for Synopsys ARC HS cores (ARCv2 ISA) running Linux has been
  added. This port requires at least binutils-2.32, gcc-8.3 and Linux-5.1.
  Three ABIs are supported:

     - arc-linux-gnu
     - arc-linux-gnuhf
     - arceb-linux-gnu

  The arc* ABIs are little-endian while arceb is big-endian.  All ABIs use
  64-bit time (y2038 safe) and 64-bit file offsets (LFS default).

* The GNU C Library now loads audit modules listed in the DT_AUDIT and
  DT_DEPAUDIT dynamic section entries of the main executable.

* powerpc64le supports IEEE128 long double libm/libc redirects when
  using -mabi=ieeelongdouble to compile C code on supported GCC
  toolchains.  It is recommended to use GCC 8 or newer when testing
  this option.

* To help detect buffer overflows and other out-of-bounds accesses
  several APIs have been annotated with GCC 'access' attribute.  This
  should help GCC 10 issue better warnings.

* On Linux, functions pthread_attr_setsigmask_np and
  pthread_attr_getsigmask_np have been added.  They allow applications
  to specify the signal mask of a thread created with pthread_create.

* The GNU C Library now provides the header file <sys/single_threaded.h>
  which declares the variable __libc_single_threaded.  Applications are
  encouraged to use this variable for single-thread optimizations,
  instead of weak references to symbols historically defined in
  libpthread.

* The functions sigabbrev_np and sigdescr_np have been added.  The
  sigabbrev_np function returns the abbreviated signal name (e.g. "HUP" for
  SIGHUP) while sigdescr_np returns a string describing the signal number
  (e.g "Hangup" for SIGHUP).  Different than strsignal, sigdescr_np does not
  attempt to translate the return description, both functions return
  NULL for an invalid signal number.

  They should be used instead of sys_siglist or sys_sigabbrev and they
  are both thread and async-signal safe.  These functions are GNU extensions.

* The functions strerrorname_np and strerrordesc_np have been added.  The
  strerroname_np function returns error number name (e.g. "EINVAL" for EINVAL)
  while strerrordesc_np returns a string describing the error number
  (e.g "Invalid argument" for EINVAL).  Different than strerror,
  strerrordesc_np does not attempt to translate the return description, both
  functions return NULL for an invalid error number.

  They should be used instead of sys_errlist and sys_nerr, both are
  thread and async-signal safe.  These functions are GNU extensions.

* AArch64 now supports standard branch protection security hardening
  in glibc when it is built with a GCC that is configured with
  --enable-standard-branch-protection (or if -mbranch-protection=standard
  flag is passed when building both GCC target libraries and glibc,
  in either case a custom GCC is needed).  This includes branch target
  identification (BTI) and pointer authentication for return addresses
  (PAC-RET).  They require armv8.5-a and armv8.3-a architecture
  extensions respectively for the protection to be effective,
  otherwise the used instructions are nops.  User code can use PAC-RET
  without libc support, but BTI requires a libc that is built with BTI
  support, otherwise runtime objects linked into user code will not be
  BTI compatible.

Deprecated and removed features, and other changes affecting compatibility:

* Remove configure option --enable-obsolete-rpc.  Sun RPC is removed
  from glibc.  This includes the rpcgen program, librpcsvc, and the Sun
  RPC header files.  Backward compatibility for old programs is kept
  only for architectures and ABIs that have been added in or before
  glibc 2.31.  New programs need to use TI-RPC
  <http://git.linux-nfs.org/?p=steved/libtirpc.git;a=summary> and
  rpcsvc-proto <https://github.com/thkukuk/rpcsvc-proto>.

* Remove configure option --enable-obsolete-nsl.  libnsl is only built
  as shared library for backward compatibility and the NSS modules "nis"
  and "nisplus" are not built at all and libnsl's headers aren't
  installed.  This compatibility is kept only for architectures and ABIs
  that have been added in or before version 2.28.  Replacement
  implementations based on TI-RPC, which additionally support IPv6, are
  available from <https://github.com/thkukuk/>.  This change does not
  affect the "compat" NSS module, which does not depend on libnsl
  since 2.27 and thus can be used without NIS.

* The deprecated <sys/sysctl.h> header and the sysctl function have been
  removed.  To support old binaries, the sysctl function continues to
  exist as a compatibility symbol (on those architectures which had it),
  but always fails with ENOSYS.  This reflects the removal of the system
  call from all architectures, starting with Linux 5.5.

* The sstk function is no longer available to newly linked binaries.
  Its implementation always returned with a failure, and the function
  was not declared in any header file.

* The legacy signal handling functions siginterrupt, sigpause, sighold,
  sigrelse, sigignore and sigset, and the sigmask macro have been
  deprecated.  Applications should use the sigsuspend, sigprocmask and
  sigaction functions instead.

* ldconfig now defaults to the new format for ld.so.cache. glibc has
  already supported this format for almost 20 years.

* The deprecated arrays sys_siglist, _sys_siglist, and sys_sigabbrev
  are no longer available to newly linked binaries, and their declarations
  have been removed from <string.h>.  They are exported solely as
  compatibility symbols to support old binaries.  All programs should use
  strsignal instead.

* The deprecated symbols sys_errlist, _sys_errlist, sys_nerr, and _sys_nerr
  are no longer available to newly linked binaries, and their declarations
  have been removed from <stdio.h>.  They are exported solely as
  compatibility symbols to support old binaries.  All programs should use
  strerror or strerror_r instead.

* Both strerror and strerror_l now share the same internal buffer in the
  calling thread, meaning that the returned string pointer may be invalided
  or contents might be overwritten on subsequent calls in the same thread or
  if the thread is terminated.  It makes strerror MT-safe.

* Using weak references to libpthread functions such as pthread_create
  or pthread_key_create to detect the singled-threaded nature of a
  program is an obsolescent feature.  Future versions of glibc will
  define pthread_create within libc.so.6 itself, so such checks will
  always flag the program as multi-threaded.  Applications should check
  the __libc_single_threaded variable declared in
  <sys/single_threaded.h> instead.

* The "files" NSS module no longer supports the "key" database (used for
  secure RPC).  The contents of the /etc/publickey file will be ignored,
  regardless of the settings in /etc/nsswitch.conf.  (This method of
  storing RPC keys only supported the obsolete and insecure AUTH_DES
  flavor of secure RPC.)

* The __morecore and __after_morecore_hook malloc hooks and the default
  implementation __default_morecore have been deprecated.  Applications
  should use malloc interposition to change malloc behavior, and mmap to
  allocate anonymous memory.  A future version of glibc may require that
  applications which use the malloc hooks must preload a special shared
  object, to enable the hooks.

* The hesiod NSS module has been deprecated and will be removed in a
  future version of glibc.  System administrators are encouraged to
  switch to other approaches for networked account databases, such as
  LDAP.

Changes to build and runtime requirements:

* powerpc64le requires GCC 7.4 or newer.  This is required for supporting
  long double redirects.

Security related changes:

  CVE-2016-10228: An infinite loop has been fixed in the iconv program when
  invoked with the -c option and when processing invalid multi-byte input
  sequences.  Reported by Jan Engelhardt.

  CVE-2020-10029: Trigonometric functions on x86 targets suffered from stack
  corruption when they were passed a pseudo-zero argument.  Reported by Guido
  Vranken / ForAllSecure Mayhem.

  CVE-2020-1752: A use-after-free vulnerability in the glob function when
  expanding ~user has been fixed.

  CVE-2020-6096: A signed comparison vulnerability in the ARMv7 memcpy and
  memmove functions has been fixed.  Discovered by Jason Royes and Samual
  Dytrych of the Cisco Security Assessment and Penetration Team (See
  TALOS-2020-1019).

The following bugs are resolved with this release:

  [9809] localedata: ckb_IQ: new Kurdish Sorani locale
  [10441] manual: Backtraces code example lacks error checking
  [10815] librt: [timer_create / SIGEV_THREAD] signalmask of
    timer_sigev_thread dangerous
  [14231] stdio: stdio-common tests memory requirements
  [14578] libc: /proc-based emulation for lchmod, fchmodat
  [16272] dynamic-link: dlopen()ing a DT_FILTER library crashes if
    filtee has constructor
  [19519] locale: iconv(1) with -c option hangs on illegal multi-byte
    sequences (CVE-2016-10228)
  [19737] admin: Doc page “20.5.2 Infinity and NaN” has incorrect HTML
    character entities for infinity & pi
  [20338] libc: Parsing of /etc/gshadow can return bad pointers causing
    segfaults in applications
  [20543] libc: Please move from .gnu.linkonce to comdat
  [22489] network: gcc warns about implicit convertion in
    ICMP6_FILTER_SETPASS with -Wsign-conversion
  [22525] localedata: or_IN  LC_COLLATE does not use copy "iso14651_t1"
  [23294] math: Complex _FloatN functions are redirected to the wrong
    function with -mlong-double-64
  [23296] libc: Data race in setting function descriptor during lazy
    binding
  [23668] dynamic-link: ldconfig: Default to the new format for
    ld.so.cache
  [23819] hurd: hurd: Add C11 thread support
  [23990] build: test-container error out on failure to exec child.
  [23991] build: shell-container typo in run_command_array
  [24638] manual: Error in example of parsing a template string
  [24654] manual: Wrong declaration of wcschr in libc manual
  [24943] dynamic-link: Support DT_AUDIT, DT_DEPAUDIT in the dynamic
    linker
  [25051] dynamic-link: aarch64, powerpc64 uses surplus static tls for
    dynamically loaded dsos
  [25098] nptl: nptl: ctype classification functions are not AS-Safe
  [25219] libc: improve out-of-bounds checking with GCC 10 attribute
    access
  [25262] libc: getcontext/setcontext/swapcontext unnecessarily save and
    restore EAX, ECX and EDX
  [25397] dynamic-link: Legacy bitmap doesn't cover jitted code
  [25414] glob: 'glob' use-after-free bug (CVE-2020-1752)
  [25420] network: Race condition in resolv_conf.c can result in caching
    stale configuration forever
  [25487] math: sinl() stack corruption from crafted input
    (CVE-2020-10029)
  [25506] build: configure: broken detection of STT_GNU_IFUNC when GCC
    defaults to PIE
  [25523] libc: MIPS/Linux inline syscall template is miscompiled
  [25620] libc: Signed comparison vulnerability in the ARMv7 memcpy()
    (CVE-2020-6096)
  [25623] libc: test-sysvmsg, test-sysvsem, test-sysvshm fail with 2.31
    on 32 bit and old kernel
  [25635] libc: arm: Wrong sysdep order selection for soft-fp
  [25639] localedata: Some names of days and months wrongly spelt in
    Occitan
  [25657] libc: sigprocmask() and sigisemptyset() manipulate different
    amount of sigset_t bytes
  [25691] stdio: printf: memory leak when printing long multibyte
    strings
  [25715] libc: system() returns wrong errors when posix_spawn fails
  [25733] malloc: mallopt(M_MXFAST) can set global_max_fast to 0
  [25734] locale: mbrtowc with Big5-HKSCS fails to reset conversion
    state for conversions that produce two Unicode code points
  [25765] nptl: Incorrect futex syscall in __pthread_disable_asynccancel
    for linux x86_64 leads to livelock
  [25788] dynamic-link: [i386] -fno-omit-frame-pointer in CFLAGS causes
    test failures, invalid instruction in ld.so
  [25790] glob: Typo in tst-fnmatch.input
  [25810] libc: x32: Incorrect syscall entries with pointer, off_t and
    size_t
  [25819] localedata: Update locale data to Unicode 13.0.0
  [25824] libc: Abnormal function of strnlen in aarch64
  [25887] dynamic-link: Wasted space in _dl_x86_feature_1[1]
  [25896] libc: Incorrect prctl
  [25902] libc: Bad LOADARGS_N
  [25905] dynamic-link: VSX registers are corrupted during PLT
    resolution when glibc is built with --disable-multi-arch and --with-
    cpu=power9
  [25933] string: Off by one error in __strncmp_avx2 when
    length=VEC_SIZE*4 and strings are at page boundaries can cause a
    segfault
  [25942] nptl: Deadlock on stack_cache_lock between __nptl_setxid and
    exiting detached thread
  [25966] libc: Incorrect access of __x86_shared_non_temporal_threshold
    for x32
  [25976] nss: internal_end*ent in nss_compat may clobber errno, hiding
    ERANGE
  [25999] nptl: Use-after-free issue in pthread_getaddr_default_np
  [26073] math: getpayload() has wrong return value
  [26076] dynamic-link: dlmopen crashes after failing to load
    dependencies in audit mode
  [26120] localedata: column width of  of some Korean
    JUNGSEONG/JONGSEONG characters wrong (should be 0)
  [26128] libc: Incorrect bit_cpu_CLFLUSHOPT
  [26133] libc: Incorrect need_arch_feature_F16C
  [26137] libc: strtod() triggers exception FE_INEXACT on reasonable
    input
  [26149] libc: PKU is usable only if OSPKE is set
  [26173] libc: powerpc64*: Add @notoc to calls to functions that do not
    preserve r2
  [26208] libc: Incorrect bit_cpu_CLFSH
  [26210] network: Incorrect use of hidden symbols for global sunrpc
    variables
  [26211] stdio: printf integer overflow calculating allocation size
  [26214] stdio: printf_fp double free
  [26215] stdio: printf_fp memory leak
  [26232] time: FAIL: support/tst-timespec for 32-bit targets
  [26258] nss: nss_compat should not read input files with mmap
  [26332] string: Incorrect cache line size load causes memory
    corruption in memset


Version 2.31

Major new features:

* The GNU C Library now supports a feature test macro _ISOC2X_SOURCE to
  enable features from the draft ISO C2X standard.  Only some features from
  this draft standard are supported by the GNU C Library, and as the draft
  is under active development, the set of features enabled by this macro is
  liable to change.  Features from C2X are also enabled by _GNU_SOURCE, or
  by compiling with "gcc -std=gnu2x".

* The <math.h> functions that round their results to a narrower type now
  have corresponding type-generic macros in <tgmath.h>, as defined in TS
  18661-1:2014 and TS 18661-3:2015 as amended by the resolution of
  Clarification Request 13 to TS 18661-3.

* The function pthread_clockjoin_np has been added, enabling join with a
  terminated thread with a specific clock.  It allows waiting against
  CLOCK_MONOTONIC and CLOCK_REALTIME.  This function is a GNU extension.

* New locale added: mnw_MM (Mon language spoken in Myanmar).

* The DNS stub resolver will optionally send the AD (authenticated data) bit
  in queries if the trust-ad option is set via the options directive in
  /etc/resolv.conf (or if RES_TRUSTAD is set in _res.options).  In this
  mode, the AD bit, as provided by the name server, is available to
  applications which call res_search and related functions.  In the default
  mode, the AD bit is not set in queries, and it is automatically cleared in
  responses, indicating a lack of DNSSEC validation.  (Therefore, the name
  servers and the network path to them are treated as untrusted.)

Deprecated and removed features, and other changes affecting compatibility:

* The totalorder and totalordermag functions, and the corresponding
  functions for other floating-point types, now take pointer arguments to
  avoid signaling NaNs possibly being converted to quiet NaNs in argument
  passing.  This is in accordance with the resolution of Clarification
  Request 25 to TS 18661-1, as applied for C2X.  Existing binaries that pass
  floating-point arguments directly will continue to work.

* The obsolete function stime is no longer available to newly linked
  binaries, and its declaration has been removed from <time.h>.
  Programs that set the system time should use clock_settime instead.

* We plan to remove the obsolete function ftime, and the header <sys/timeb.h>,
  in a future version of glibc.  In this release, the header still exists
  but calling ftime will cause a compiler warning.  All programs should use
  gettimeofday or clock_gettime instead.

* The gettimeofday function no longer reports information about a
  system-wide time zone.  This 4.2-BSD-era feature has been deprecated for
  many years, as it cannot handle the full complexity of the world's
  timezones, but hitherto we have supported it on a best-effort basis.
  Changes required to support 64-bit time_t on 32-bit architectures have
  made this no longer practical.

  As of this release, callers of gettimeofday with a non-null 'tzp' argument
  should expect to receive a 'struct timezone' whose tz_minuteswest and
  tz_dsttime fields are zero.  (For efficiency reasons, this does not always
  happen on a few Linux-based ports.  This will be corrected in a future
  release.)

  All callers should supply a null pointer for the 'tzp' argument to
  gettimeofday.  For accurate information about the time zone associated
  with the current time, use the localtime function.

  gettimeofday itself is obsolescent according to POSIX.  We have no plans
  to remove access to this function, but portable programs should consider
  using clock_gettime instead.

* The settimeofday function can still be used to set a system-wide time
  zone when the operating system supports it.  This is because the Linux
  kernel reused the API, on some architectures, to describe a system-wide
  time-zone-like offset between the software clock maintained by the kernel,
  and the "RTC" clock that keeps time when the system is shut down.

  However, to reduce the odds of this offset being set by accident,
  settimeofday can no longer be used to set the time and the offset
  simultaneously.  If both of its two arguments are non-null, the call
  will fail (setting errno to EINVAL).

  Callers attempting to set this offset should also be prepared for the call
  to fail and set errno to ENOSYS; this already happens on the Hurd and on
  some Linux architectures.  The Linux kernel maintainers are discussing a
  more principled replacement for the reused API.  After a replacement
  becomes available, we will change settimeofday to fail with ENOSYS on all
  platforms when its 'tzp' argument is not a null pointer.

  settimeofday itself is obsolescent according to POSIX.  Programs that set
  the system time should use clock_settime and/or the adjtime family of
  functions instead.  We may cease to make settimeofday available to newly
  linked binaries after there is a replacement for Linux's time-zone-like
  offset API.

* SPARC ISA v7 is no longer supported.  v8 is still supported, but only if
  the optional CAS instruction is implemented (for instance, LEON processors
  are still supported, but SuperSPARC processors are not).

  As the oldest 64-bit SPARC ISA is v9, this only affects 32-bit
  configurations.

* If a lazy binding failure happens during dlopen, during the execution of
  an ELF constructor, the process is now terminated.  Previously, the
  dynamic loader would return NULL from dlopen, with the lazy binding error
  captured in a dlerror message.  In general, this is unsafe because
  resetting the stack in an arbitrary function call is not possible.

* For MIPS hard-float ABIs, the GNU C Library will be configured to need an
  executable stack unless explicitly configured at build time to require
  minimum kernel version 4.8 or newer.  This is because executing
  floating-point branches on a non-executable stack on Linux kernels prior to
  4.8 can lead to application crashes for some MIPS configurations. While
  currently PT_GNU_STACK is not widely used on MIPS, future releases of GCC are
  expected to enable non-executable stack by default  with PT_GNU_STACK by
  default and is thus likely to trigger a crash on older kernels.

  The GNU C Library can be built with --enable-kernel=4.8.0 in order to keep a
  non-executable stack while dropping support for older kernels.

* System call wrappers for time system calls now use the new time64 system
  calls when available. On 32-bit targets, these wrappers attempt to call
  the new system calls first and fall back to the older 32-bit time system
  calls if they are not present.  This may cause issues in environments
  that cannot handle unsupported system calls gracefully by returning
  -ENOSYS. Seccomp sandboxes are affected by this issue.

Changes to build and runtime requirements:

* It is no longer necessary to have recent Linux kernel headers to build
  working (non-stub) system call wrappers on all architectures except 64-bit
  RISC-V.  64-bit RISC-V requires a minimum kernel headers version of 5.0.

* The ChangeLog file is no longer present in the toplevel directory of the
  source tree.  ChangeLog files are located in the ChangeLog.old directory as
  ChangeLog.N where the highest N has the latest entries.

Security related changes:

  CVE-2020-1751: A defect in the PowerPC backtrace function could cause an
  out-of-bounds write when executed in a signal frame context.

  CVE-2019-19126: ld.so failed to ignore the LD_PREFER_MAP_32BIT_EXEC
  environment variable during program execution after a security
  transition, allowing local attackers to restrict the possible mapping
  addresses for loaded libraries and thus bypass ASLR for a setuid
  program.  Reported by Marcin Kościelnicki.

The following bugs are resolved with this release:

  [12031] localedata: iconv -t ascii//translit with Greek characters
  [15813] libc: Multiple issues in __gen_tempname
  [17726] libc: [arm, sparc] profil_counter should be compat symbol
  [18231] libc: ipc_perm struct's mode member has wrong type in sys/ipc.h
  [19767] libc: vdso is not used with static linking
  [19903] hurd: Shared mappings not being inherited by children processes
  [20358] network: RES_USE_DNSSEC sets DO; should also have a way to set AD
  [20839] dynamic-link: Incomplete rollback of dynamic linker state on
    linking failure
  [23132] localedata: Missing transliterations in Miscellaneous Mathematical
    Symbols-A/B Unicode blocks
  [23518] libc: Eliminate __libc_utmp_jump_table
  [24026] malloc: malloc_info() returns wrong numbers
  [24054] localedata: Many locales are missing date_fmt
  [24214] dynamic-link: user defined ifunc resolvers may run in ldd mode
  [24304] dynamic-link: Lazy binding failure during ELF
    constructors/destructors is not fatal
  [24376] libc: RISC-V symbol size confusion with _start
  [24682] localedata: zh_CN first weekday should be Monday per GB/T
    7408-2005
  [24824] libc: test-in-container does not install charmap files compatible
    with localedef
  [24844] regex: regex bad pointer / leakage if malloc fails
  [24867] malloc: Unintended malloc_info formatting changes
  [24879] libc: login: utmp alarm timer can arrive after lock acquisition
  [24880] libc: login: utmp implementation uses struct flock with fcntl64
  [24882] libc: login: pututline uses potentially outdated cache
  [24899] libc: Missing nonstring attributes in <utmp.h>, <utmpx.h>
  [24902] libc: login: Repeating pututxline on EINTR/EAGAIN causes stale
    utmp entries
  [24916] dynamic-link: [MIPS] Highest EI_ABIVERSION value not raised to
    ABSOLUTE ABI
  [24930] dynamic-link: dlopen of PIE executable can result in
    _dl_allocate_tls_init assertion failure
  [24950] localedata: Top-of-tree glibc does not build with top-of-tree GCC
    (stringop-overflow error)
  [24959] time: librt IFUNC resolvers for clock_gettime and clock_*
    functions other  can lead to crashes
  [24967] libc: jemalloc static linking causes runtime failure
  [24986] libc: alpha: new getegid, geteuid and getppid syscalls used
    unconditionally
  [25035] libc: sbrk() failure handled poorly in tunables_strdup
  [25087] dynamic-link: ldconfig mishandles unusual .dynstr placement
  [25097] libc: new -Warray-bounds with GCC 10
  [25112] dynamic-link: dlopen must not make new objects accessible when it
    still can fail with an error
  [25139] localedata: Please add the new mnw_MM locale
  [25149] regex: Array bounds violation in proceed_next_node
  [25157] dynamic-link: Audit cookie for the dynamic loader is not
    initialized correctly
  [25189] libc: glibc's __glibc_has_include causes issues with clang
    -frewrite-includes
  [25194] malloc: malloc.c: do_set_mxfast incorrectly casts the mallopt
    value to an unsigned
  [25204] dynamic-link: LD_PREFER_MAP_32BIT_EXEC not ignored in setuid
    binaries (CVE-2019-19126)
  [25225] libc: ld.so fails to link on x86 if GCC defaults to -fcf-
    protection
  [25226] string: strstr: Invalid result if needle crosses page on s390-z15
    ifunc variant.
  [25232] string: <string.h> does not enable const correctness for strchr et
    al. for Clang++
  [25233] localedata: Consider "." as the thousands separator for sl_SI
    (Slovenian)
  [25241] nptl: __SIZEOF_PTHREAD_MUTEX_T defined twice for x86
  [25251] build: Failure to run tests when CFLAGS contains -DNDEBUG.
  [25271] libc: undeclared identifier PTHREAD_MUTEX_DEFAULT when compiling
    with -std=c11
  [25323] localedata: km_KH: d_t_fmt contains "m" instead of "%M"
  [25324] localedata: lv_LV: d_t_fmt contains suspicious words in the time
    part
  [25396] dynamic-link: Failing dlopen can leave behind dangling GL
    (dl_initfirst) link map pointer
  [25401] malloc: pvalloc must not have __attribute_alloc_size__
  [25423] libc: Array overflow in backtrace on powerpc
  [25425] network: Missing call to __resolv_context_put in
    getaddrinfo.c:gethosts


Version 2.30

Major new features:

* Unicode 12.1.0 Support: Character encoding, character type info, and
  transliteration tables are all updated to Unicode 12.1.0, using
  generator scripts contributed by Mike FABIAN (Red Hat).

* The dynamic linker accepts the --preload argument to preload shared
  objects, in addition to the LD_PRELOAD environment variable.

* The twalk_r function has been added.  It is similar to the existing
  twalk function, but it passes an additional caller-supplied argument
  to the callback function.

* On Linux, the getdents64, gettid, and tgkill functions have been added.

* Minguo (Republic of China) calendar support has been added as an
  alternative calendar for the following locales: zh_TW, cmn_TW, hak_TW,
  nan_TW, lzh_TW.

* The entry for the new Japanese era has been added for ja_JP locale.

* Memory allocation functions malloc, calloc, realloc, reallocarray, valloc,
  pvalloc, memalign, and posix_memalign fail now with total object size
  larger than PTRDIFF_MAX.  This is to avoid potential undefined behavior with
  pointer subtraction within the allocated object, where results might
  overflow the ptrdiff_t type.

* The dynamic linker no longer refuses to load objects which reference
  versioned symbols whose implementation has moved to a different soname
  since the object has been linked.  The old error message, symbol
  FUNCTION-NAME, version SYMBOL-VERSION not defined in file DSO-NAME with
  link time reference, is gone.

* Add new POSIX-proposed pthread_cond_clockwait, pthread_mutex_clocklock,
  pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock and sem_clockwait
  functions.  These behave similarly to their "timed" equivalents, but also
  accept a clockid_t parameter to determine which clock their timeout should
  be measured against.  All functions allow waiting against CLOCK_MONOTONIC
  and CLOCK_REALTIME.  The decision of which clock to be used is made at the
  time of the wait (unlike with pthread_condattr_setclock, which requires
  the clock choice at initialization time).

* On AArch64 the GNU IFUNC resolver call ABI changed: old resolvers still
  work, new resolvers can use a second argument which can be extended in
  the future, currently it contains the AT_HWCAP2 value.

Deprecated and removed features, and other changes affecting compatibility:

* The copy_file_range function fails with ENOSYS if the kernel does not
  support the system call of the same name.  Previously, user space
  emulation was performed, but its behavior did not match the kernel
  behavior, which was deemed too confusing.  Applications which use the
  copy_file_range function can no longer rely on glibc to provide a fallback
  on kernels that do not support the copy_file_range system call, and if
  this function returns ENOSYS, they will need to use their own fallback.
  Support for copy_file_range for most architectures was added in version
  4.5 of the mainline Linux kernel.

* The functions clock_gettime, clock_getres, clock_settime,
  clock_getcpuclockid, clock_nanosleep were removed from the librt library
  for new applications (on architectures which had them).  Instead, the
  definitions in libc will be used automatically, which have been available
  since glibc 2.17.

* The obsolete and never-implemented XSI STREAMS header files <stropts.h>
  and <sys/stropts.h> have been removed.

* Support for the "inet6" option in /etc/resolv.conf and the RES_USE_INET6
  resolver flag (deprecated in glibc 2.25) have been removed.

* The obsolete RES_INSECURE1 and RES_INSECURE2 option flags for the DNS stub
  resolver have been removed from <resolv.h>.

* With --enable-bind-now, installed programs are now linked with the
  BIND_NOW flag.

* Support for the PowerPC SPE ISA extension (powerpc-*-*gnuspe*
  configurations) has been removed, following the deprecation of this
  subarchitecture in version 8 of GCC, and its removal in version 9.

* On 32-bit Arm, support for the port-based I/O emulation and the <sys/io.h>
  header have been removed.

* The Linux-specific <sys/sysctl.h> header and the sysctl function have been
  deprecated and will be removed from a future version of glibc.
  Application should directly access /proc instead.  For obtaining random
  bits, the getentropy function can be used.

Changes to build and runtime requirements:

* GCC 6.2 or later is required to build the GNU C Library.

  Older GCC versions and non-GNU compilers are still supported when
  compiling programs that use the GNU C Library.

Security related changes:

  CVE-2019-7309: x86-64 memcmp used signed Jcc instructions to check
  size.  For x86-64, memcmp on an object size larger than SSIZE_MAX
  has undefined behavior.  On x32, the size_t argument may be passed
  in the lower 32 bits of the 64-bit RDX register with non-zero upper
  32 bits.  When it happened with the sign bit of RDX register set,
  memcmp gave the wrong result since it treated the size argument as
  zero.  Reported by H.J. Lu.

  CVE-2019-9169: Attempted case-insensitive regular-expression match
  via proceed_next_node in posix/regexec.c leads to heap-based buffer
  over-read.  Reported by Hongxu Chen.

The following bugs are resolved with this release:

  [2872] locale: Transliteration Cyrillic -> ASCII fails
  [6399] libc: gettid() should have a wrapper
  [16573] malloc: mtrace hangs when MALLOC_TRACE is defined
  [16976] glob: fnmatch unbounded stack VLA for collating symbols
  [17396] localedata: globbing for locale by [[.collating-element.]]
  [18035] dynamic-link: pldd does no longer work, enters infinite loop
  [18465] malloc: memusagestat is built using system C library
  [18830] locale: iconv -c -f ascii with >buffer size worth of input before
    invalid input drops valid char
  [20188] nptl: libpthread IFUNC resolver for vfork can lead to crash
  [20568] locale: Segfault with wide characters and setlocale/fgetwc/UTF-8
  [21897] localedata: Afar locales: Fix mon, abmon, and abday
  [22964] localedata: The Japanese Era name will be changed on May 1, 2019
  [23352] malloc: __malloc_check_init still defined in public header
    malloc.h.
  [23403] nptl: Wrong alignment of TLS variables
  [23501] libc: nftw() doesn't return dangling symlink's inode
  [23733] malloc: Check the count before calling tcache_get()
  [23741] malloc: Missing __attribute_alloc_size__ in many allocation
    functions
  [23831] localedata: nl_NL missing LC_NUMERIC thousands_sep
  [23844] nptl: pthread_rwlock_trywrlock results in hang
  [23983] argparse: Missing compat versions of argp_failure and argp_error
    for long double = double
  [23984] libc: Missing compat versions of err.h and error.h functions for
    long double = double
  [23996] localedata: Dutch salutations
  [24040] libc: riscv64: unterminated call chain in __thread_start
  [24047] network: libresolv should use IP_RECVERR/IPV6_RECVERR to avoid
    long timeouts
  [24051] stdio: puts and putchar output to _IO_stdout instead of stdout
  [24059] nss: nss_files: get_next_alias calls fgets_unlocked without
    checking for NULL.
  [24114] regex: regexec buffer read overrun in "grep -i
    '\(\(\)*.\)*\(\)\(\)\1'"
  [24122] libc: Segfaults if 0 returned from la_version
  [24153] stdio: Some input functions do not react to stdin assignment
  [24155] string: x32 memcmp can treat positive length as 0 (if sign bit in
    RDX is set) (CVE-2019-7309)
  [24161] nptl: __run_fork_handlers self-deadlocks in malloc/tst-mallocfork2
  [24164] libc: Systemtap probes need to use "nr" constraint on 32-bit Arm,
    not the default "nor"
  [24166] dynamic-link: Dl_serinfo.dls_serpath[1] in dlfcn.h causes UBSAN
    false positives, change to modern flexible array
  [24180] nptl: pthread_mutex_trylock does not use the correct order of
    instructions while maintaining the robust mutex list due to missing
    compiler barriers.
  [24194] librt: Non-compatibility symbols for clock_gettime etc. cause
    unnecessary librt dependencies
  [24200] localedata: Revert first_weekday removal in en_IE locale
  [24211] nptl: Use-after-free in Systemtap probe in pthread_join
  [24215] nptl: pthread_timedjoin_np should be a cancellation point
  [24216] malloc: Check for large bin list corruption when inserting
    unsorted chunk
  [24228] stdio: old x86 applications that use legacy libio crash on exit
  [24231] dynamic-link: [sparc64] R_SPARC_H34 implementation falls through
    to R_SPARC_H44
  [24293] localedata: Missing Minguo calendar support for TW locales
  [24296] localedata: Orthographic mistakes in 'day' and 'abday' sections in
    tt_RU (Tatar) locale
  [24307] localedata: Update locale data to Unicode 12.0.0
  [24323] dynamic-link: dlopen should not be able open PIE objects
  [24335] build: "Obsolete types detected" with Linux 5.0 headers
  [24369] localedata: Orthographic mistakes in 'mon' and 'abmon' sections in
    tt_RU (Tatar) locale
  [24370] localedata: Add lang_name for tt_RU locale
  [24372] locale: Binary locale files are not architecture independent
  [24394] time: strptime %Ey mis-parses final year of era
  [24476] dynamic-link: __libc_freeres triggers bad free in libdl if dlerror
    was not used
  [24506] dynamic-link: FAIL: elf/tst-pldd with --enable-hardcoded-path-in-
    tests
  [24531] malloc: Malloc tunables give tcache assertion failures
  [24532] libc: conform/arpa/inet.h failures due to linux kernel 64-bit
    time_t changes
  [24535] localedata: Update locale data to Unicode 12.1.0
  [24537] build: nptl/tst-eintr1 test case can hit task limits on some
    kernels and break testing
  [24544] build: elf/tst-pldd doesn't work if you install with a --prefix
  [24556] build: [GCC 9] error: ‘%s’ directive argument is null
    [-Werror=format-overflow=]
  [24570] libc: alpha: compat msgctl uses __IPC_64
  [24584] locale: Data race in __wcsmbs_clone_conv
  [24588] stdio: Remove codecvt vtables from libio
  [24603] math: sysdeps/ieee754/dbl-64/branred.c is slow when compiled with
    -O3 -march=skylake
  [24614] localedata: nl_NL LC_MONETARY doesn't match CLDR 35
  [24632] stdio: Old binaries which use freopen with default stdio handles
    crash
  [24640] libc: __ppc_get_timebase_freq() always return 0 when using static
    linked glibc
  [24652] localedata: szl_PL spelling correction
  [24695] nss: nss_db: calling getpwent after endpwent crashes
  [24696] nss: endgrent() clobbers errno=ERRNO for 'group: db files' entry
    in /etc/nsswitch.conf
  [24699] libc: mmap64 with very large offset broken on MIPS64 n32
  [24740] libc: getdents64 type confusion
  [24741] dynamic-link: ld.so should not require that a versioned symbol is
    always implemented in the same library
  [24744] libc: Remove copy_file_range emulation
  [24757] malloc: memusagestat is linked against system libpthread
  [24794] libc: Partial test suite run builds corrupt test-in-container
    testroot


Version 2.29

Major new features:

* The getcpu wrapper function has been added, which returns the currently
