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GNU C Library NEWS -- history of user-visible changes.
Copyright (C) 1992-2022 Free Software Foundation, Inc.
See the end for copying conditions.
Please send GNU C library bug reports via <https://sourceware.org/bugzilla/>
using `glibc' in the "product" field.
Version 2.35.1
The following bugs are resolved with this release:
[28850] linux: __get_nprocs_sched reads uninitialized memory from the stack
[28853] libc: tst-spawn6 changes current foreground process group
(breaks test isolation)
[28860] build: --enable-kernel=5.1.0 build fails because of missing
__convert_scm_timestamps
[28865] linux: _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are inaccurate
without /sys and /proc
Version 2.35
Major new features:
* Unicode 14.0.0 Support: Character encoding, character type info, and
transliteration tables are all updated to Unicode 14.0.0, using
generator scripts contributed by Mike FABIAN (Red Hat).
* Bump r_version in the debugger interface to 2 and add a new field,
r_next, support multiple namespaces.
* Support for the C.UTF-8 locale has been added to glibc. The locale
supports full code-point sorting for all valid Unicode code points. A
limitation in the framework for fnmatch, regexec, and regcomp requires
a compromise to save space and only ASCII-based range expressions are
supported for now (see bug 28255). The full size of the locale is
only ~400KiB, with 346KiB coming from LC_CTYPE information for
Unicode. This locale harmonizes downstream C.UTF-8 already shipping
in various downstream distributions. The locale is not built into
glibc, and must be installed.
* <math.h> functions that round their results to a narrower type, and
corresponding <tgmath.h> macros, are added from TS 18661-1:2014, TS
18661-3:2015 and draft ISO C2X:
- fsqrt, fsqrtl, dsqrtl and corresponding fMsqrtfN, fMsqrtfNx,
fMxsqrtfN and fMxsqrtfNx functions.
- ffma, ffmal, dfmal and corresponding fMfmafN, fMfmafNx, fMxfmafN and
fMxfmafNx functions.
* <math.h> functions for floating-point maximum and minimum,
corresponding to new operations in IEEE 754-2019, and corresponding
<tgmath.h> macros, are added from draft ISO C2X: fmaximum,
fmaximum_num, fmaximum_mag, fmaximum_mag_num, fminimum, fminimum_num,
fminimum_mag, fminimum_mag_num and corresponding functions for float,
long double, _FloatN and _FloatNx.
* <math.h> macros for single-precision float constants are added as a
GNU extension: M_Ef, M_LOG2Ef, M_LOG10Ef, M_LN2f, M_LN10f, M_PIf,
M_PI_2f, M_PI_4f, M_1_PIf, M_2_PIf, M_2_SQRTPIf, M_SQRT2f and
M_SQRT1_2f.
* The __STDC_IEC_60559_BFP__ and __STDC_IEC_60559_COMPLEX__ macros are
predefined as specified in TS 18661-1:2014.
* The exp10 functions in <math.h> now have a corresponding type-generic
macro in <tgmath.h>.
* The ISO C2X macro _PRINTF_NAN_LEN_MAX has been added to <stdio.h>.
* printf-family functions now support the %b format for output of
integers in binary, as specified in draft ISO C2X, and the %B variant
of that format recommended by draft ISO C2X.
* A new DSO sorting algorithm has been added in the dynamic linker that uses
topological sorting by depth-first search (DFS), solving performance issues
of the existing sorting algorithm when encountering particular circular
object dependency cases.
* A new tunable, glibc.rtld.dynamic_sort, can be used to select between
the two DSO sorting algorithms. The default setting of '2' uses the
new DFS-based algorithm. The setting '1' switches to the old
algorithm used in glibc 2.33 and earlier.
* ABI support for a new function '__memcmpeq'. '__memcmpeq' is meant
to be used by compilers for optimizing usage of 'memcmp' when its
return value is only used for its boolean status.
* Support for automatically registering threads with the Linux rseq
system call has been added. This system call is implemented starting
from Linux 4.18. The Restartable Sequences ABI accelerates user-space
operations on per-cpu data. It allows user-space to perform updates
on per-cpu data without requiring heavy-weight atomic operations.
Automatically registering threads allows all libraries, including
libc, to make immediate use of the rseq support by using the
documented ABI, via the __rseq_flags, __rseq_offset, and __rseq_size
variables. The GNU C Library manual has details on integration of
Restartable Sequences.
* A symbolic link to the dynamic linker is now installed under
/usr/bin/ld.so (or more precisely, '${bindir}/ld.so').
* All programs and the testsuite in glibc are now built as position independent
executables (PIE) by default on toolchains and architectures that support it.
Further, if the toolchain and architecture supports it, even static programs
are built as PIE and the resultant glibc can be used to build static PIE
executables. A new option --disable-default-pie has been added to disable
this behavior and get a non-PIE build. This option replaces
--enable-static-pie, which no longer has any effect on the build
configuration.
* On Linux, a new tunable, glibc.malloc.hugetlb, can be used to
either make malloc issue madvise plus MADV_HUGEPAGE on mmap and sbrk
or to use huge pages directly with mmap calls with the MAP_HUGETLB
flags). The former can improve performance when Transparent Huge Pages
is set to 'madvise' mode while the latter uses the system reserved
huge pages.
* The printf family of functions now handles the flagged %#m conversion
specifier, printing errno as an error constant (similar to strerrorname_np).
* The function _dl_find_object has been added. In-process unwinders
can use it to efficiently locate unwinding information for a code
address.
* Support for OpenRISC running on Linux has been added. This port requires
as least binutils 2.35, GCC 11, and Linux 5.4. Currently only soft-float
ABI is supported:
- or1k-linux-gnu
The OpenRISC ABI is 32-bit big-endian and uses 64-bit time (y2038 safe) and
64-bit file offsets (LFS default).
* A new configure option, --with-rtld-early-cflags, can be used to
specify additional compiler flags for building the early startup code
of the dynamic linker. On targets which have CPU compatibility
checks, this can help to ensure that proper diagnostics are printed if
the dynamic loader runs on an incompatible CPU.
* On Linux, the epoll_pwait2 function has been added. It is similar to
epoll_wait with the difference the timeout has nanoseconds resolution.
* The function posix_spawn_file_actions_addtcsetpgrp_np has been added,
enabling posix_spawn and posix_spawnp to set the controlling terminal in
the new process in a race free manner. This function is a GNU extension.
* Source fortification (_FORTIFY_SOURCE) level 3 is now available for
applications compiling with glibc and gcc 12 and later. Level 3 leverages
the __builtin_dynamic_object_size function to deliver additional
fortification balanced against additional runtime cost (checking non-constant
bounds).
Deprecated and removed features, and other changes affecting compatibility:
* On x86-64, the LD_PREFER_MAP_32BIT_EXEC environment variable support
has been removed since the first PT_LOAD segment is no longer executable
due to defaulting to -z separate-code.
* The r_version update in the debugger interface makes the glibc binary
incompatible with GDB binaries built without the following commits:
c0154a4a21a gdb: Don't assume r_ldsomap when r_version > 1 on Linux
4eb629d50d4 gdbserver: Check r_version < 1 for Linux debugger interface
when audit modules or dlmopen are used.
* Intel MPX support (lazy PLT, ld.so profile, and LD_AUDIT) has been removed.
* The --enable-static-pie option is no longer available. The glibc build
configuration script now automatically detects static-pie support in the
toolchain and architecture and enables it if available.
* The catchsegv script and associated libSegFault.so shared object have
been removed. There are widely-deployed out-of-process alternatives for
catching coredumps and backtraces.
* Support for prelink will be removed in the next release; this includes
removal of the LD_TRACE_PRELINKING, and LD_USE_LOAD_BIAS, environment
variables and their functionality in the dynamic loader.
Changes to build and runtime requirements:
* The audit module interface version LAV_CURRENT is increased to enable
proper bind-now support. The loader now advertises via the la_symbind
flags that PLT trace is not possible. New audit modules require the
new dynamic loader supporing the latest LAV_CURRENT version. Old audit
modules are still loaded for all targets except aarch64.
* The audit interface on aarch64 is extended to support both the indirect
result location register (x8) and NEON Q register. Old audit modules are
rejected by the loader. Audit modules must be rebuilt to use the newer
structure sizes and the latest module interface version for LAV_CURRENT.
Security related changes:
CVE-2022-23219: Passing an overlong file name to the clnt_create
legacy function could result in a stack-based buffer overflow when
using the "unix" protocol. Reported by Martin Sebor.
CVE-2022-23218: Passing an overlong file name to the svcunix_create
legacy function could result in a stack-based buffer overflow.
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:
[12889] nptl: Race condition in pthread_kill
[14232] nptl: tst-cancel7 and tst-cancelx7 race condition
[14913] libc: [mips] Clean up MIPS 64-bit register-dump.h output
[15310] dynamic-link: _dl_sort_fini is O(n^3) causing slow exit when
many dsos
[15333] libc: Use 64-bit stat functions in installed programs
[15533] dynamic-link: LD_AUDIT introduces an avoidable performance
degradation
[15971] dynamic-link: No interface for debugger access to libraries
loaded with dlmopen
[17318] locale: [RFE] Provide a C.UTF-8 locale by default
[17645] dynamic-link: RFE: Improve performance of dynamic loader for
deeply nested DSO dependencies.
[19193] nptl: pthread_kill, pthread_cancel return ESRCH for a thread
ID whose lifetime has not ended
[22542] network: buffer overflow in sunrpc clnt_create
(CVE-2022-23219)
[22716] malloc: [PATCH] mtrace.pl: use TRACE_PRELINKING instead of
TRACE_LOADED_OBJECTS
[25947] malloc: memory leak in muntrace
[26045] math: fmaxf(inf, nan) does not always work
[26108] math: exp10() has problems with <tgmath.h>
[26779] build: benign use after realloc at localealias.c:329
[27609] dynamic-link: [2.32/2.33/2.34 Regression] In elf/dl-open.c
(_dl_open) we might use __LM_ID_CALLER to index GL(dl_ns)[]
[27945] build: build-many-glibcs.py doesn't configure GCC with
--enable-initfini-array
[27991] build: x86: sysdeps/x86/configure.ac breaks when
libc_cv_include_x86_isa_level is loaded from cache
[28036] nptl: Incorrect types for pthread_mutexattr_set/getrobust_np
in __REDIRECT_NTH macro
[28061] dynamic-link: A failing dlmopen called by an auditor crashed
[28062] dynamic-link: Suppress audit calls when a (new) namespace is
empty
[28126] libc: nftw aborts for paths longer than PATH_MAX
[28129] dynamic-link: Unnecessary check DT_DEBUG in ld.so
[28153] libc: [test] gmon/tst-gmon-gprof* may have a f3 line when
built with ld.lld
[28182] libc: _TIME_BITS=64 in C++ has issues with fcntl, ioctl, prctl
[28185] math: Inaccurate j0f function (again)
[28199] locale: iconvconfig prefix flag behaves differently in glibc
2.34
[28203] dynamic-link: aarch64: elf_machine_{load_address,dynamic}
should drop _GLOBAL_OFFSET_TABLE_[0] in favor of __ehdr_start for
robustness
[28213] librt: NULL pointer dereference in mq_notify (CVE-2021-38604)
[28223] libc: mips: clone does not align stack
[28253] dynamic-link: Missing colon in LD_SHOW_AUXV output after
AT_MINSIGSTKSZ
[28256] malloc: Conditional jump or move depends on uninitialised
value(s) in __GI___tunables_init
[28260] build: io/tst-closefrom, misc/tst-close_range, posix/tst-
spawn5 fail if stray fds are open
[28310] libc: Do not use affinity mask for sysconf
(_SC_NPROCESSORS_CONF)
[28338] time: undefined behavior in __tzfile_compute with oddball TZif
file
[28340] dynamic-link: ld.so crashes while loading a DSO with a read-
only dynamic section
[28349] libc: Segfault for ping -R on qemux86 caused by recvmsg()
[28350] libc: ping receives SIGABRT on lib32-qemux86-64 caused by
recvmsg()
[28353] network: Race condition on __opensock
[28357] dynamic-link: deadlock between pthread_create and ctors
[28358] math: f64xdivf128 and f64xmulf128 spurious underflows
[28361] nptl: Fix for bug 12889 causes setxid deadlock
[28368] build: -Waddress instances in stdio-common/vfprintf-internal.c
[28390] localedata: Update locale data to Unicode 14.0.0
[28397] math: tgmath.h should not define fmaxmag, fminmag macros for
C2X
[28400] libc: [2.35 Regression] string/test-strncasecmp: cannot set
locale "en_US.UTF-8"
[28407] nptl: pthread_kill assumes that kill (getpid ()) is equivalent
to tgkill (getpid (), gettid())
[28455] dynamic-link: -Wl,--enable-new-dtags doesn't work
[28457] dynamic-link: Missing reldepmod4.so dependency for
globalmod1.so
[28469] time: linux: struct timex is not correctly set for 32-bit
systems with TIMESIZE=64
[28470] regex: Buffer read overrun in regular expression searching
[28475] string: Incorrect access attribute on memfrob
[28524] libc: Conversion from ISO-2022-JP-3 with iconv may emit
spurious NUL character on state reset
[28532] libc: powerpc64[le]: CFI for assembly templated syscalls is
incorrect
[28550] dynamic-link: FAIL: tst-dso-
ordering9_112-ecbda(GLIBC_TUNABLES=glibc.rtld.dynamic_sort=1)
execution test
[28554] build: Undefined generate-md5
[28572] libc: Misaligned accesses in test-memcpy and test-mempcpy on
hppa
[28607] nptl: Masked signals are delivered on thread exit
[28624] libc: openjdk 8/9 assume uni processor and gets stuck due to
lack of cpu counting /proc fallback with glibc 2.34
[28646] string: [2.35 Regression] mock -r fedora-36-x86_64
/tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build
[28648] dynamic-link: Running ld.so on statically linked binaries
crashes
[28656] dynamic-link: LD_PREFER_MAP_32BIT_EXEC no longer works due to
binutils changes
[28676] dynamic-link: p_align on PT_LOAD segment in DSO isn't honored
[28678] nptl: nptl/tst-create1 hangs sporadically
[28688] dynamic-link: PT_LOAD p_align check is too strict
[28700] nss: "dns [!UNAVAIL=return] files" default for hosts database
is not useful
[28707] time: assert in tzfile.c __tzfile_read striking with truncated
timezones generated by tzcode-2021d and later
[28713] math: GCC 12 miscompiles libm
[28732] dynamic-link: FAIL: elf/tst-dl_find_object
[28738] build: LIBC_LINKER_FEATURE doesn't work on linker -z option
[28745] dynamic-link: _dl_find_object miscompilation on powerpc64le
[28746] libc: _FORTIFY_SOURCE does not work for stpcpy
[28749] libc: Inconsistency detected by ld.so: rtld.c: 1632: dl_main:
Assertion `GL(dl_rtld_map).l_libname' failed!
[28755] string: overflow bug in wcsncmp_avx2 and wcsncmp_evex
[28757] nptl: GDB printer tests failed with new GDB
[28765] math: x86_64 libmvec atan2 accuracy
[28766] manual: Document libmvec accuracy
[28768] network: Buffer overflow in svcunix_create with long pathnames
(CVE-2022-23218)
[28769] libc: Off-by-one buffer overflow/underflow in getcwd()
(CVE-2021-3999)
[28770] libc: Unexpected return value from realpath() for too long
results (CVE-2021-3998)
[28771] libc: %ebx optimization macros are incompatible with .altmacro
in Systemtap probes
[28780] build: --disable-default-pie doesn't work on static programs
[28782] libc: x86-64 ISA level for glibc itself is always
x86-64-baseline
[28792] glob: possible wrong behaviour with patterns with double [
with no closing ]
[28837] libc: FAIL: socket/tst-socket-timestamp-compat
[28847] locale: Empty mon_decimal_point in LC_MONETARY results in non-
empty mon_decimal_point_wc
Version 2.34
Major new features:
* In order to support smoother in-place-upgrades and to simplify
the implementation of the runtime all functionality formerly
implemented in the libraries libpthread, libdl, libutil, libanl has
been integrated into libc. New applications do not need to link with
-lpthread, -ldl, -lutil, -lanl anymore. For backwards compatibility,
empty static archives libpthread.a, libdl.a, libutil.a, libanl.a are
provided, so that the linker options keep working. Applications which
have been linked against glibc 2.33 or earlier continue to load the
corresponding shared objects (which are now empty). The integration
of those libraries into libc means that additional symbols become
available by default. This can cause applications that contain weak
references to take unexpected code paths that would only have been
used in previous glibc versions when e.g. preloading libpthread.so.0,
potentially exposing application bugs.
* When _DYNAMIC_STACK_SIZE_SOURCE or _GNU_SOURCE are defined,
PTHREAD_STACK_MIN is no longer constant and is redefined to
sysconf(_SC_THREAD_STACK_MIN). This supports dynamic sized register
sets for modern architectural features like Arm SVE.
* Add _SC_MINSIGSTKSZ and _SC_SIGSTKSZ. When _DYNAMIC_STACK_SIZE_SOURCE
or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ are no longer
constant on Linux. MINSIGSTKSZ is redefined to sysconf(_SC_MINSIGSTKSZ)
and SIGSTKSZ is redefined to sysconf (_SC_SIGSTKSZ). This supports
dynamic sized register sets for modern architectural features like
Arm SVE.
* The dynamic linker implements the --list-diagnostics option, printing
a dump of information related to IFUNC resolver operation and
glibc-hwcaps subdirectory selection.
* On Linux, the function execveat has been added. It operates similar to
execve and it is is already used to implement fexecve without requiring
/proc to be mounted. However, different than fexecve, if the syscall is not
supported by the kernel an error is returned instead of trying a fallback.
* The ISO C2X function timespec_getres has been added.
* The feature test macro __STDC_WANT_IEC_60559_EXT__, from draft ISO
C2X, is supported to enable declarations of functions defined in Annex F
of C2X. Those declarations are also enabled when
__STDC_WANT_IEC_60559_BFP_EXT__, as specified in TS 18661-1, is
defined, and when _GNU_SOURCE is defined.
* On powerpc64*, glibc can now be compiled without scv support using the
--disable-scv configure option.
* Add support for 64-bit time_t on configurations like x86 where time_t
is traditionally 32-bit. Although time_t still defaults to 32-bit on
these configurations, this default may change in future versions.
This is enabled with the _TIME_BITS preprocessor macro set to 64 and is
only supported when LFS (_FILE_OFFSET_BITS=64) is also enabled. It is
only enabled for Linux and the full support requires a minimum kernel
version of 5.1.
* The main gconv-modules file in glibc now contains only a small set of
essential converter modules and the rest have been moved into a supplementary
configuration file gconv-modules-extra.conf in the gconv-modules.d directory
in the same GCONV_PATH. Similarly, external converter modules directories
may have supplementary configuration files in a gconv-modules.d directory
with names ending with .conf to logically classify the converter modules in
that directory.
* On Linux, a new tunable, glibc.pthread.stack_cache_size, can be used
to configure the size of the thread stack cache.
* The function _Fork has been added as an async-signal-safe fork replacement
since Austin Group issue 62 droped the async-signal-safe requirement for
fork (and it will be included in the future POSIX standard). The new _Fork
function does not run any atfork function neither resets any internal state
or lock (such as the malloc one), and only sets up a minimal state required
to call async-signal-safe functions (such as raise or execve). This function
is currently a GNU extension.
* On Linux, the close_range function has been added. It allows efficiently
closing a range of file descriptors on recent kernels (version 5.9).
* The function closefrom has been added. It closes all file descriptors
greater than or equal to a given integer. This function is a GNU extension,
although it is also present in other systems.
* The posix_spawn_file_actions_addclosefrom_np function has been added,
enabling posix_spawn and posix_spawnp to close all file descriptors greater
than or equal to a given integer. This function is a GNU extension,
although Solaris also provides a similar function.
* When invoked explicitly, the dynamic linker now uses the kernel to
execute programs that do not have any dynamic dependency (that is,
they are statically linked). This feature is Linux-specific.
* The audit libraries will avoid unnecessary slowdown if it is not required
PLT tracking (by not implementing the la_pltenter or la_pltexit callbacks).
Deprecated and removed features, and other changes affecting compatibility:
* The function pthread_mutex_consistent_np has been deprecated; programs
should use the equivalent standard function pthread_mutex_consistent
instead.
* The function pthread_mutexattr_getrobust_np has been deprecated;
programs should use the equivalent standard function
pthread_mutexattr_getrobust instead.
* The function pthread_mutexattr_setrobust_np has been deprecated;
programs should use the equivalent standard function
pthread_mutexattr_setrobust instead.
* The function pthread_yield has been deprecated; programs should use
the equivalent standard function sched_yield instead.
* The function inet_neta declared in <arpa/inet.h> has been deprecated.
* Various rarely-used functions declared in <resolv.h> and
<arpa/nameser.h> have been deprecated. Applications are encouraged to
use dedicated DNS processing libraries if applicable. For <resolv.h>,
this affects the functions dn_count_labels, fp_nquery, fp_query,
fp_resstat, hostalias, loc_aton, loc_ntoa, p_cdname, p_cdnname,
p_class, p_fqname, p_fqnname, p_option, p_query, p_rcode, p_time,
p_type, putlong, putshort, res_hostalias, res_isourserver,
res_nameinquery, res_queriesmatch, res_randomid, sym_ntop, sym_ntos,
sym_ston. For <arpa/nameser.h>, the functions ns_datetosecs,
ns_format_ttl, ns_makecanon, ns_parse_ttl, ns_samedomain, ns_samename,
ns_sprintrr, ns_sprintrrf, ns_subdomain have been deprecated.
* Various symbols previously defined in libresolv have been moved to libc
in order to prepare for libresolv moving entirely into libc (see earlier
entry for merging libraries into libc). The symbols __dn_comp,
__dn_expand, __dn_skipname, __res_dnok, __res_hnok, __res_mailok,
__res_mkquery, __res_nmkquery, __res_nquery, __res_nquerydomain,
__res_nsearch, __res_nsend, __res_ownok, __res_query, __res_querydomain,
__res_search, __res_send formerly in libresolv have been renamed and no
longer have a __ prefix. They are now available in libc.
* The pthread cancellation handler is now installed with SA_RESTART and
pthread_cancel will always send the internal SIGCANCEL on a cancellation
request. It should not be visible to applications since the cancellation
handler should either act upon cancellation (if asynchronous cancellation
is enabled) or ignore the cancellation internal signal. However there are
buggy kernel interfaces (for instance some CIFS versions) that could still
see a spurious EINTR error when cancellation interrupts a blocking syscall.
* Previously, glibc installed its various shared objects under versioned
file names such as libc-2.33.so. The ABI sonames (e.g., libc.so.6)
were provided as symbolic links. Starting with glibc 2.34, the shared
objects are installed under their ABI sonames directly, without
symbolic links. This increases compatibility with distribution
package managers that delete removed files late during the package
upgrade or downgrade process.
* The symbols mallwatch and tr_break are now deprecated and no longer used in
mtrace. Similar functionality can be achieved by using conditional
breakpoints within mtrace functions from within gdb.
* The __morecore and __after_morecore_hook malloc hooks and the default
implementation __default_morecore have been removed from the API. Existing
applications will continue to link against these symbols but the interfaces
no longer have any effect on malloc.
* Debugging features in malloc such as the MALLOC_CHECK_ environment variable
(or the glibc.malloc.check tunable), mtrace() and mcheck() have now been
disabled by default in the main C library. Users looking to use these
features now need to preload a new debugging DSO libc_malloc_debug.so to get
this functionality back.
* The deprecated functions malloc_get_state and malloc_set_state have been
moved from the core C library into libc_malloc_debug.so. Legacy applications
that still use these functions will now need to preload libc_malloc_debug.so
in their environment using the LD_PRELOAD environment variable.
* The deprecated memory allocation hooks __malloc_hook, __realloc_hook,
__memalign_hook and __free_hook are now removed from the API. Compatibility
symbols are present to support legacy programs but new applications can no
longer link to these symbols. These hooks no longer have any effect on glibc
functionality. The malloc debugging DSO libc_malloc_debug.so currently
supports hooks and can be preloaded to get this functionality back for older
programs. However this is a transitional measure and may be removed in a
future release of the GNU C Library. Users may port away from these hooks by
writing and preloading their own malloc interposition library.
Changes to build and runtime requirements:
* On Linux, the shm_open, sem_open, and related functions now expect the
file shared memory file system to be mounted at /dev/shm. These functions
no longer search among the system's mount points for a suitable
replacement if /dev/shm is not available.
Security related changes:
CVE-2021-27645: The nameserver caching daemon (nscd), when processing
a request for netgroup lookup, may crash due to a double-free,
potentially resulting in degraded service or Denial of Service on the
local system. Reported by Chris Schanzle.
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-2021-35942: The wordexp function may overflow the positional
parameter number when processing the expansion resulting in a crash.
Reported by Philippe Antoine.
The following bugs are resolved with this release:
[4737] libc: fork is not async-signal-safe
[5781] math: Slow dbl-64 sin/cos/sincos for special values
[10353] libc: Methods for deleting all file descriptors greater than
given integer (closefrom)
[14185] glob: fnmatch() fails when '*' wildcard is applied on the file
name containing multi-byte character(s)
[14469] math: Inaccurate j0f function
[14470] math: Inaccurate j1f function
[14471] math: Inaccurate y0f function
[14472] math: Inaccurate y1f function
[14744] nptl: kill -32 $pid or kill -33 $pid on a process cancels a
random thread
[15271] dynamic-link: dlmopen()ed shared library with LM_ID_NEWLM
crashes if it fails dlsym() twice
[15648] nptl: multiple definition of `__lll_lock_wait_private'
[16063] nptl: Provide a pthread_once variant in libc directly
[17144] libc: syslog is not thread-safe if NO_SIGPIPE is not defined
[17145] libc: syslog with LOG_CONS leaks console file descriptor
[17183] manual: description of ENTRY struct in <search.h> in glibc
manual is incorrect
[18435] nptl: pthread_once hangs when init routine throws an exception
[18524] nptl: Missing calloc error checking in
__cxa_thread_atexit_impl
[19329] dynamic-link: dl-tls.c assert failure at concurrent
pthread_create and dlopen
[19366] nptl: returning from a thread should disable cancellation
[19511] nptl: 8MB memory leak in pthread_create in case of failure
when non-root user changes priority
[20802] dynamic-link: getauxval NULL pointer dereference after static
dlopen
[20813] nptl: pthread_exit is inconsistent between libc and libpthread
[22057] malloc: malloc_usable_size is broken with mcheck
[22668] locale: LC_COLLATE: the last character of ellipsis is not
ordered correctly
[23323] libc: [RFE] CSU startup hardening.
[23328] malloc: Remove malloc hooks and ensure related APIs return no
data.
[23462] dynamic-link: Static binary with dynamic string tokens ($LIB,
$PLATFORM, $ORIGIN) crashes
[23489] libc: "gcc -lmcheck" aborts on free when using posix_memalign
[23554] nptl: pthread_getattr_np reports wrong stack size with
MULTI_PAGE_ALIASING
[24106] libc: Bash interpreter in ldd script is taken from host
[24773] dynamic-link: dlerror in an secondary namespace does not use
the right free implementation
[25036] localedata: Update collation order for Swedish
[25383] libc: where_is_shmfs/__shm_directory/SHM_GET_NAME may cause
shm_open to pick wrong directory
[25680] dynamic-link: ifuncmain9picstatic and ifuncmain9picstatic
crash in IFUNC resolver due to stack canary (--enable-stack-
protector=all)
[26874] build: -Warray-bounds in _IO_wdefault_doallocate
[26983] math: [x86_64] x86_64 tgamma has too large ULP error
[27111] dynamic-link: pthread_create and tls access use link_map
objects that may be concurrently freed by dlclose
[27132] malloc: memusagestat is linked to system librt, leading to
undefined symbols on major version upgrade
[27136] dynamic-link: dtv setup at thread creation may leave an entry
uninitialized
[27249] libc: libSegFault.so does not output signal number properly
[27304] nptl: pthread_cond_destroy does not pass private flag to futex
system calls
[27318] dynamic-link: glibc fails to load binaries when built with
-march=sandybridge: CPU ISA level is lower than required
[27343] nss: initgroups() SIGSEGVs when called on a system without
nsswich.conf (in a chroot)
[27346] dynamic-link: x86: PTWRITE feature check is missing
[27389] network: NSS chroot hardening causes regressions in chroot
deployments
[27403] dynamic-link: aarch64: tlsdesc htab is not freed on dlclose
[27444] libc: sysconf reports unsupported option (-1) for
_SC_LEVEL1_ICACHE_LINESIZE on X86 since v2.33
[27462] nscd: double-free in nscd (CVE-2021-27645)
[27468] malloc: aarch64: realloc crash with heap tagging: FAIL:
malloc/tst-malloc-thread-fail
[27498] dynamic-link: __dl_iterate_phdr lacks unwinding information
[27511] libc: S390 memmove assumes Vector Facility when MIE Facility 3
is present
[27522] glob: glob, glob64 incorrectly marked as __THROW
[27555] dynamic-link: Static tests fail with --enable-stack-
protector=all
[27559] libc: fstat(AT_FDCWD) succeeds (it shouldn't) and returns
information for the current directory
[27577] dynamic-link: elf/ld.so --help doesn't work
[27605] libc: tunables can't control xsave/xsavec selection in
dl_runtime_resolve_*
[27623] libc: powerpc: Missing registers in sc[v] clobbers list
[27645] libc: [linux] sysconf(_SC_NPROCESSOR...) breaks down on
containers
[27646] dynamic-link: Linker error for non-existing NSS symbols (e.g.
_nss_files_getcanonname_r) from within a dlmopen namespace.
[27648] libc: FAIL: misc/tst-select
[27650] stdio: vfscanf returns too early if a match is longer than
INT_MAX
[27651] libc: Performance regression after updating to 2.33
[27655] string: Wrong size calculation in string/test-strnlen.c
[27706] libc: select fails to update timeout on error
[27709] libc: arm: FAIL: debug/tst-longjmp_chk2
[27721] dynamic-link: x86: ld_audit ignores bind now for TLSDESC and
tries resolving them lazily
[27744] nptl: Support different libpthread/ld.so load orders in
libthread_db
[27749] libc: Data race __run_exit_handlers
[27761] libc: getconf: Segmentation fault when passing '-vq' as
argument
[27832] nss: makedb.c:797:7: error: 'writev' specified size 4294967295
exceeds maximum object size 2147483647
[27870] malloc: MALLOC_CHECK_ causes realloc(valid_ptr, TOO_LARGE) to
not set ENOMEM
[27872] build: Obsolete configure option --enable-stackguard-
randomization
[27873] build: tst-cpu-features-cpuinfo fail when building on AMD cpu
[27882] localedata: Use U+00AF MACRON in more EBCDIC charsets
[27892] libc: powerpc: scv ABI error handling fails to check
IS_ERR_VALUE
[27896] nptl: mq_notify does not handle separately allocated thread
attributes (CVE-2021-33574)
[27901] libc: TEST_STACK_ALIGN doesn't work
[27902] libc: The x86-64 clone wrapper fails to align child stack
[27914] nptl: Install SIGSETXID handler with SA_ONSTACK
[27939] libc: aarch64: clone does not align the stack
[27968] libc: s390x: clone does not align the stack
[28011] libc: Wild read in wordexp (parse_param) (CVE-2021-35942)
[28024] string: s390(31bit): Wrong result of memchr (MEMCHR_Z900_G5)
with n >= 0x80000000
[28028] malloc: malloc: tcache shutdown sequence does not work if the
thread never allocated anything
[28033] libc: Need to check RTM_ALWAYS_ABORT for RTM
[28064] string: x86_64:wcslen implementation list has wcsnlen
[28067] libc: FAIL: posix/tst-spawn5
[28068] malloc: FAIL: malloc/tst-mallocalign1-mcheck
[28071] time: clock_gettime, gettimeofday, time lost vDSO acceleration
on older kernels
[28075] nis: Out-of-bounds static buffer read in nis_local_domain
[28089] build: tst-tls20 fails when linker defaults to --as-needed
[28090] build: elf/tst-cpu-features-cpuinfo-static fails on certain
AMD64 cpus
[28091] network: ns_name_skip may return 0 for domain names without
terminator
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.
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()
[23091] hurd: missing waitid support
[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