glibc 发布 2.21 版本，下载地址：
http://ftp.gnu.org/gnu/libc/glibc-2.21.tar.gz
详细改进内容：
* The following bugs are resolved with this release:
6652, 10672, 12674, 12847, 12926, 13862, 14132, 14138, 14171, 14498,
15215, 15378, 15884, 16009, 16418, 16191, 16469, 16576, 16617, 16618,
16619, 16657, 16740, 16857, 17192, 17266, 17273, 17344, 17363, 17370,
17371, 17411, 17460, 17475, 17485, 17501, 17506, 17508, 17522, 17555,
17570, 17571, 17572, 17573, 17574, 17582, 17583, 17584, 17585, 17589,
17594, 17601, 17608, 17616, 17625, 17630, 17633, 17634, 17635, 17647,
17653, 17657, 17658, 17664, 17665, 17668, 17682, 17702, 17717, 17719,
17722, 17723, 17724, 17725, 17732, 17733, 17744, 17745, 17746, 17747,
17748, 17775, 17777, 17780, 17781, 17782, 17791, 17793, 17796, 17797,
17801, 17803, 17806, 17834, 17844, 17848, 17868, 17869, 17870, 17885,
17892.
* CVE-2015-1472 Under certain conditions wscanf can allocate too little
memory for the to-be-scanned arguments and overflow the allocated
buffer. The implementation now correctly computes the required buffer
size when using malloc.
* A new semaphore algorithm has been implemented in generic C code for all
machines. Previous custom assembly implementations of semaphore were
difficult to reason about or ensure that they were safe. The new version
of semaphore supports machines with 64-bit or 32-bit atomic operations.
The new semaphore algorithm is used by sem_init, sem_open, sem_post,
sem_wait, sem_timedwait, sem_trywait, and sem_getvalue.
* Port to Altera Nios II has been contributed by Mentor Graphics.
* Optimized strcpy, stpcpy, strncpy, stpncpy, strcmp, and strncmp
implementations for powerpc64/powerpc64le.
Implemented by Adhemerval Zanella (IBM).
* Added support for TSX lock elision of pthread mutexes on powerpc32, powerpc64
and powerpc64le. This may improve lock scaling of existing programs on
HTM capable systems. The lock elision code is only enabled with
--enable-lock-elision=yes. Also, the TSX lock elision implementation for
powerpc will issue a transaction abort on every syscall to avoid side
effects being visible outside transactions.
* Optimized strcpy, stpcpy, strchrnul and strrchr implementations for
AArch64. Contributed by ARM Ltd.
* i386 memcpy functions optimized with SSE2 unaligned load/store.
* CVE-2104-7817 The wordexp function could ignore the WRDE_NOCMD flag
under certain input conditions resulting in the execution of a shell for
command substitution when the applicaiton did not request it. The
implementation now checks WRDE_NOCMD immediately before executing the
shell and returns the error WRDE_CMDSUB as expected.
* CVE-2012-3406 printf-style functions could run into a stack overflow when
processing format strings with a large number of format specifiers.
* CVE-2014-9402 The nss_dns implementation of getnetbyname could run into an
infinite loop if the DNS response contained a PTR record of an unexpected
format.
* The minimum GCC version that can be used to build this version of the GNU
C Library is GCC 4.6. Older GCC versions, and non-GNU compilers, can
still be used to compile programs using the GNU C Library.
* The GNU C Library is now built with -Werror by default. This can be
disabled by configuring with --disable-werror.
* New locales: tu_IN, bh_IN, raj_IN, ce_RU.
* The obsolete sigvec function has been removed. This was the original
4.2BSD interface that inspired the POSIX.1 sigaction interface, which
programs have been using instead for about 25 years. Of course, ABI
compatibility for old binaries using sigvec remains intact.
* Merged gettext 0.19.3 into the intl subdirectory. This fixes building
with newer versions of bison.
* Support for MIPS o32 FPXX, FP64A and FP64 ABI Extensions.
The original MIPS o32 hard-float ABI requires an FPU where double-precision
registers overlay two consecutive single-precision registers. MIPS32R2
introduced a new FPU mode (FR=1) where double-precision registers extend the
corresponding single-precision registers which is incompatible with the
o32 hard-float ABI. The MIPS SIMD ASE and the MIPSR6 architecture both
require the use of FR=1 making a transition necessary. New o32 ABI
extensions enable users to migrate over time from the original o32 ABI
through to the updated o32 FP64 ABI. To achieve this the dynamic linker now
tracks the ABI of any loaded object and verifies that new objects are
compatible. Mode transitions will also be requested as required and
unsupportable objects will be rejected. The ABI checks include both soft and
hard float ABIs for o32, n32 and n64.
GCC 5 with GNU binutils 2.25 onwards:
It is strongly recommended that all o32 system libraries are built using the
new o32 FPXX ABI (-mfpxx) to facilitate the transition as this is compatible
with the original and all new o32 ABI extensions. Configure a MIPS GCC
compiler using --with-fp-32=xx to set this by default
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