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Patrick Steinhardt e75cf4a58b unix exec: avoid atexit handlers when child exits
The `grub_util_exec_redirect_all` helper function can be used to
spawn an executable and redirect its output to some files. After calling
`fork()`, the parent will wait for the child to terminate with
`waitpid()` while the child prepares its file descriptors, environment
and finally calls `execvp()`. If something in the children's setup
fails, it will stop by calling `exit(127)`.

Calling `exit()` will cause any function registered via `atexit()` to be
executed, which is usually the wrong thing to do in a child. And
actually, one can easily observe faulty behaviour on musl-based systems
without modprobe(8) installed: executing `grub-install --help` will call
`grub_util_exec_redirect_all` with "modprobe", which obviously fails if
modprobe(8) is not installed. Due to the child now exiting and invoking
the `atexit()` handlers, it will clean up some data structures of the
parent and cause it to be deadlocked in the `waitpid()` syscall.

The issue can easily be fixed by calling `_exit(127)` instead, which is
especially designed to be called when the atexit-handlers should not be
executed.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
2017-08-30 15:20:13 +02:00
asm-tests asm-tests/i386-pc: Check that movl is 5 bytes. 2016-09-28 20:31:04 +03:00
build-aux Autogenerate ChangeLog from git changelog. 2015-01-24 17:29:50 +01:00
conf Add support for device-tree-based drivers. 2017-05-08 21:19:59 +02:00
docs grub.texi: Fix typo 2017-08-14 11:36:50 +02:00
grub-core unix exec: avoid atexit handlers when child exits 2017-08-30 15:20:13 +02:00
include arc: Do not create spurious variable grub_arc_memory_type_t. 2017-08-30 15:18:24 +02:00
m4 update m4/extern-inline.m4 to upstream version to fix compilation on FreeBSD 2015-03-05 19:25:56 +03:00
po po: Use @SHELL@ rather than /bin/sh. 2017-05-03 12:46:48 +02:00
tests Allow GRUB to mount ext2/3/4 filesystems that have the encryption feature. 2017-06-29 13:29:53 +00:00
themes/starfield Starfield theme. 2012-02-23 17:21:38 +01:00
unicode * unicode: Import Unicode 6.0 data. 2011-12-25 16:17:25 +01:00
util Fail if xorriso failed. 2017-08-07 18:08:39 +02:00
.gitignore .gitignore: Add grub-core/build-grub-module-verifier 2016-11-12 12:07:31 +03:00
ABOUT-NLS automake commit without merge history 2010-05-06 11:34:04 +05:30
acinclude.m4 Fix -nopie/-nopie check. 2017-01-30 19:38:55 +01:00
AUTHORS 2005-09-03 Yoshinori K. Okuji <okuji@enbug.org> 2005-09-03 16:54:27 +00:00
autogen.sh autogen: Use cp instead of ln -s. 2015-11-08 18:45:57 +01:00
BUGS * BUGS: New file. 2011-01-11 00:06:01 +01:00
ChangeLog-2015 Autogenerate ChangeLog from git changelog. 2015-01-24 17:29:50 +01:00
config.h.in Remove libgcc dependency. 2015-03-03 20:50:37 +01:00
configure.ac Set have_exec to y on cygwin so we have grub_mkrescue. 2017-08-14 16:27:53 +02:00
COPYING 2007-07-22 Yoshinori K. Okuji <okuji@enbug.org> 2007-07-21 23:32:33 +00:00
coreboot.cfg * coreboot.cfg: Add missing file. 2013-11-20 00:52:23 +01:00
geninit.sh automake commit without merge history 2010-05-06 11:34:04 +05:30
gentpl.py arm_coreboot: Support EHCI. 2017-05-08 22:15:05 +02:00
INSTALL INSTALL: Fix mention of thumb-clang. 2017-02-02 01:11:52 +01:00
linguas.sh linguas: Don't skip ko.po. 2017-02-04 00:06:57 +01:00
Makefile.am Use core2duo for bootcheck test on 64-bit EFI. 2017-03-15 09:20:14 +01:00
Makefile.util.def Makefile.util.def: add $LIBINTL to grub-macbless flags 2016-03-13 08:11:58 +03:00
NEWS NEWS updates 2016-11-22 20:51:54 +03:00
README README: Remove dead link to the wiki 2015-11-06 04:31:23 +01:00
THANKS 2009-12-11 Robert Millan <rmh.grub@aybabtu.com> 2009-12-11 22:44:47 +00:00
TODO TODO: Remove obsolete link 2016-02-12 17:51:52 +01:00

This is GRUB 2, the second version of the GRand Unified Bootloader.
GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more
robust, more powerful, and more portable.

See the file NEWS for a description of recent changes to GRUB 2.

See the file INSTALL for instructions on how to build and install the
GRUB 2 data and program files.

Please visit the official web page of GRUB 2, for more information.
The URL is <http://www.gnu.org/software/grub/grub.html>.

More extensive documentation is available in the Info manual,
accessible using 'info grub' after building and installing GRUB 2.

There are a number of important user-visible differences from the
first version of GRUB, now known as GRUB Legacy. For a summary, please
see:

  info grub Introduction 'Changes from GRUB Legacy'