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Florian Weimer 035c012e32 Reduce the statically linked startup code [BZ #23323]
It turns out the startup code in csu/elf-init.c has a perfect pair of
ROP gadgets (see Marco-Gisbert and Ripoll-Ripoll, "return-to-csu: A
New Method to Bypass 64-bit Linux ASLR").  These functions are not
needed in dynamically-linked binaries because DT_INIT/DT_INIT_ARRAY
are already processed by the dynamic linker.  However, the dynamic
linker skipped the main program for some reason.  For maximum
backwards compatibility, this is not changed, and instead, the main
map is consulted from __libc_start_main if the init function argument
is a NULL pointer.

For statically linked binaries, the old approach based on linker
symbols is still used because there is nothing else available.

A new symbol version __libc_start_main@@GLIBC_2.34 is introduced because
new binaries running on an old libc would not run their ELF
constructors, leading to difficult-to-debug issues.
2021-02-25 12:13:02 +01:00
argp argp: Avoid undefined behaviour when invoking qsort(). 2021-02-04 16:44:29 -03:00
assert Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
benchtests benchtests: Updated json bench-variant attribute 2021-02-10 08:50:26 +05:30
bits sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] 2021-02-01 11:00:52 -08:00
catgets Update copyright dates not handled by scripts/update-copyrights. 2021-01-02 12:17:34 -08:00
ChangeLog.old Prepare for glibc 2.33 release 2021-02-01 14:15:33 -03:00
conform Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
crypt Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
csu Reduce the statically linked startup code [BZ #23323] 2021-02-25 12:13:02 +01:00
ctype Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
debug libSegFault: Fix printing signal number [BZ #27249] 2021-02-01 20:04:08 +00:00
dirent Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
dlfcn Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
elf Reduce the statically linked startup code [BZ #23323] 2021-02-25 12:13:02 +01:00
gmon Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
gnulib Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
grp Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
gshadow Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
hesiod Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
htl pthread: Refactor semaphore code 2021-02-08 14:10:42 -03:00
hurd Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
iconv Update copyright dates not handled by scripts/update-copyrights. 2021-01-02 12:17:34 -08:00
iconvdata gconv: Fix assertion failure in ISO-2022-JP-3 module (bug 27256) 2021-01-27 14:02:47 +01:00
include linux: Consolidate statvfs implementations 2021-02-11 08:00:41 -03:00
inet Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
intl Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
io Update STATX_ATTR_DAX value from Linux 5.10. 2021-01-11 14:57:08 +00:00
libio Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
locale Update automatically-generated copyright dates 2021-01-02 12:17:34 -08:00
localedata POSIX locale: Fix typo in comment 2021-01-09 12:14:44 +01:00
login Update copyright dates not handled by scripts/update-copyrights. 2021-01-02 12:17:34 -08:00
mach Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
malloc added rt to malloc/Depend [BZ #27132] 2021-02-23 10:04:45 +01:00
manual tunables: Simplify TUNABLE_SET interface 2021-02-10 19:08:33 +05:30
math math/test-tgmath2: Fix fabs failure when no long double 2021-01-15 11:24:04 +09:00
mathvec Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
misc misc: Sync cdefs.h with gnulib 2021-02-09 16:57:52 -03:00
nis Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
nptl nptl: Move elision implementations into libc 2021-02-23 14:59:34 +01:00
nptl_db Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
nscd Update copyright dates not handled by scripts/update-copyrights. 2021-01-02 12:17:34 -08:00
nss nsswitch: return result when nss database is locked [BZ #27343] 2021-02-05 13:07:10 -05:00
po Update translations 2021-02-01 14:15:16 -03:00
posix posix: Falling back to non wide mode in case of encoding error [BZ #14185] 2021-02-23 15:58:04 -03:00
pwd Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resolv Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
resource setrlimit/getrlimit: Use __nonnull to avoid null pointer 2021-02-10 08:36:17 -03:00
rt Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
scripts Use Linux 5.11 in build-many-glibcs.py. 2021-02-22 16:11:21 +00:00
setjmp Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
shadow Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
signal sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] 2021-02-01 11:00:52 -08:00
socket Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
soft-fp Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
stdio-common printf: Add smoke tests for long double 2021-02-05 09:52:52 +05:30
stdlib stdlib: Add testcase for BZ #26241 2021-01-20 11:13:53 -03:00
string string: Work around GCC PR 98512 in rawmemchr 2021-02-19 13:29:00 +01:00
sunrpc sunrpc: Fix typo in xdr_string comment 2021-02-08 13:55:03 +01:00
support elf: Fix tests that rely on ld.so.cache for cross-compiling 2021-01-29 14:08:18 -03:00
sysdeps Reduce the statically linked startup code [BZ #23323] 2021-02-25 12:13:02 +01:00
sysvipc Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
termios Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
time tst: time: Provide Y2038 tests for mktime (tst-mktime4.c) 2021-02-16 20:41:45 +01:00
timezone Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
wcsmbs Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
wctype Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
.gitattributes Assume __NR_openat is always defined 2016-03-23 23:35:08 +01:00
.gitignore Add *.pyc to .gitignore 2015-05-18 15:26:26 +05:30
abi-tags Remove the bulk of the NaCl port. 2017-05-20 08:09:10 -04:00
aclocal.m4 LIBC_SLIBDIR_RTLDDIR: substitute arguments in single quotes 2018-01-25 17:20:28 +01:00
config.h.in configure: Check for static PIE support 2021-01-21 15:54:50 +00:00
config.make.in install: Replace scripts/output-format.sed with objdump -f [BZ #26559] 2021-01-11 12:03:36 -08:00
configure configure: Remove obsolete AC_CHECK_TOOL_PREFIX 2021-02-21 18:35:30 -05:00
configure.ac configure: Replace obsolete AC_TRY_LINK with AC_LINK_IFELSE 2021-02-21 18:39:01 -05:00
COPYING
COPYING.LIB
extra-lib.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
gen-locales.mk Improve gen-locales.mk and gen-locale.sh to make test files with @ options work 2018-02-27 17:01:57 +01:00
INSTALL Update INSTALL with package versions that are known to work 2021-01-25 13:13:17 -03:00
libc-abis riscv: support GNU indirect function 2021-01-10 21:25:13 -05:00
libof-iterator.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
LICENSES Prefer https to http for gnu.org and fsf.org URLs 2019-09-07 02:43:31 -07:00
MAINTAINERS Add MAINTAINERS 2017-05-11 13:38:30 -04:00
Makeconfig Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
Makefile Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
Makefile.help Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules Makerules: Do not require startup files for format.lds probe object 2021-01-12 12:22:47 +01:00
NEWS NEWS: Add missing bug closures 2021-02-23 13:36:06 +01:00
o-iterator.mk
README Documentation for the RISC-V 32-bit port 2020-08-27 08:17:44 -07:00
Rules Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
shlib-versions Remove --enable-obsolete-nsl configure flag 2020-07-08 17:25:57 +02:00
test-skeleton.c Update copyright dates with scripts/update-copyrights 2021-01-02 12:17:34 -08:00
version.h Fix version.h for glibc 2.34 development 2021-02-02 08:22:25 -03:00

This directory contains the sources of the GNU C Library.
See the file "version.h" for what release version you have.

The GNU C Library is the standard system C library for all GNU systems,
and is an important part of what makes up a GNU system.  It provides the
system API for all programs written in C and C-compatible languages such
as C++ and Objective C; the runtime facilities of other programming
languages use the C library to access the underlying operating system.

In GNU/Linux systems, the C library works with the Linux kernel to
implement the operating system behavior seen by user applications.
In GNU/Hurd systems, it works with a microkernel and Hurd servers.

The GNU C Library implements much of the POSIX.1 functionality in the
GNU/Hurd system, using configurations i[4567]86-*-gnu.

When working with Linux kernels, this version of the GNU C Library
requires Linux kernel version 3.2 or later.

Also note that the shared version of the libgcc_s library must be
installed for the pthread library to work correctly.

The GNU C Library supports these configurations for using Linux kernels:

	aarch64*-*-linux-gnu
	alpha*-*-linux-gnu
	arc*-*-linux-gnu
	arm-*-linux-gnueabi
	csky-*-linux-gnuabiv2
	hppa-*-linux-gnu
	i[4567]86-*-linux-gnu
	x86_64-*-linux-gnu	Can build either x86_64 or x32
	ia64-*-linux-gnu
	m68k-*-linux-gnu
	microblaze*-*-linux-gnu
	mips-*-linux-gnu
	mips64-*-linux-gnu
	powerpc-*-linux-gnu	Hardware or software floating point, BE only.
	powerpc64*-*-linux-gnu	Big-endian and little-endian.
	s390-*-linux-gnu
	s390x-*-linux-gnu
	riscv32-*-linux-gnu
	riscv64-*-linux-gnu
	sh[34]-*-linux-gnu
	sparc*-*-linux-gnu
	sparc64*-*-linux-gnu

If you are interested in doing a port, please contact the glibc
maintainers; see https://www.gnu.org/software/libc/ for more
information.

See the file INSTALL to find out how to configure, build, and install
the GNU C Library.  You might also consider reading the WWW pages for
the C library at https://www.gnu.org/software/libc/.

The GNU C Library is (almost) completely documented by the Texinfo manual
found in the `manual/' subdirectory.  The manual is still being updated
and contains some known errors and omissions; we regret that we do not
have the resources to work on the manual as much as we would like.  For
corrections to the manual, please file a bug in the `manual' component,
following the bug-reporting instructions below.  Please be sure to check
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Please see https://www.gnu.org/software/libc/bugs.html for bug reporting
information.  We are now using the Bugzilla system to track all bug reports.
This web page gives detailed information on how to report bugs properly.

The GNU C Library is free software.  See the file COPYING.LIB for copying
conditions, and LICENSES for notices about a few contributions that require
these additional notices to be distributed.  License copyright years may be
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