niansa-misc/musl
1
0
Fork 0
mirror of git://git.musl-libc.org/musl synced 2025-03-06 20:48:29 +01:00
Code Issues Projects Releases Packages Wiki Activity
musl - an implementation of the standard library for Linux-based systems
4769 commits 2 branches 77 tags 7.8 MiB
C 93.1%
Assembly 4.8%
C++ 1.3%
Awk 0.4%
Makefile 0.3%
Other 0.1%
Find a file
Rich Felker d64148a874 fix potential unsynchronized access to killlock state at thread exit 
as reported by Alexey Izbyshev, when the second-to-last thread exits
causing a return to single-threaded (no locks needed) state, it
creates a situation where the last remaining thread may obtain the
killlock that's already held by the exiting thread. this means it may
erroneously use the tid of the exiting thread, and may corrupt the
lock state due to double-unlock.

commit 8d81ba8c0b, which (re)introduced
the switch back to single-threaded state, documents the intent that
the first lock after switching back should provide the necessary
synchronization. this is correct, but only works if the switch back is
made after there is no further need for synchronization with locks
(other than the thread list lock, which can't be bypassed) held by the
exiting thread.

in order to hit the bug, the remaining thread must first take a
different lock, causing it to perform an actual lock one last time,
consume the need_locks==-1 state, and transition to need_locks==0.
after that, the next attempt to lock the exiting thread's killlock
will bypass locking.

fix this by reordering the unlocking of killlock at thread exit time,
along with changes to the state protected by it, to occur earlier,
before the switch to single-threaded state. there are really no
constraints on where it's done, except that it occur after there is no
longer any possibility of application code executing in the exiting
thread, so do it as early as possible.
2022-10-19 14:01:32 -04:00
arch re-enable vdso clock_gettime on arm (32-bit) with workaround 2022-09-19 13:21:54 -04:00
compat/time32 remove LFS64 symbol aliases; replace with dynamic linker remapping 2022-10-19 14:01:31 -04:00
crt remove unnecessary and problematic _Noreturn from crt/ldso startup 2019-06-25 19:05:40 -04:00
dist add another example option to dist/config.mak 2012-04-24 16:49:11 -04:00
include remove LFS64 programming interfaces (macro-only) from _GNU_SOURCE 2022-10-19 14:01:31 -04:00
ldso remove LFS64 symbol aliases; replace with dynamic linker remapping 2022-10-19 14:01:31 -04:00
src fix potential unsynchronized access to killlock state at thread exit 2022-10-19 14:01:32 -04:00
tools fix incorrect escaping in add-cfi.*.awk scripts 2020-01-20 15:57:29 -05:00
.gitignore remove obsolete gitignore rules 2016-07-06 00:21:25 -04:00
.mailmap update contributor name 2019-12-07 12:21:35 -05:00
configure configure: disable TBAA optimization because most compilers are buggy 2022-10-19 14:01:31 -04:00
COPYRIGHT add optimized aarch64 memcpy and memset 2020-06-26 17:49:51 -04:00
dynamic.list fix regression in access to optopt object 2018-11-19 13:20:41 -05:00
INSTALL fix typo in INSTALL 2020-11-29 00:46:38 -05:00
Makefile make mallocng the default malloc implementation 2020-06-30 15:38:27 -04:00
README update version reference in the README file 2014-06-25 14:16:53 -04:00
VERSION release 1.2.3 2022-04-07 13:12:40 -04:00
WHATSNEW release 1.2.3 2022-04-07 13:12:40 -04:00

README 

    musl libc

musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.

The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.

For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:

    http://www.musl-libc.org/