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Jann Horn 06e62a46bb fork: don't copy inconsistent signal handler state to child
Before this change, if a multithreaded process forks while one of its
threads is changing a signal handler using sigaction(), the memcpy() in
copy_sighand() can race with the struct assignment in do_sigaction().  It
isn't clear whether this can cause corruption of the userspace signal
handler pointer, but it definitely can cause inconsistency between
different fields of struct sigaction.

Take the appropriate spinlock to avoid this.

I have tested that this patch prevents inconsistency between sa_sigaction
and sa_flags, which is possible before this patch.

Link: http://lkml.kernel.org/r/20180702145108.73189-1-jannh@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:51 -07:00
Documentation kernel/hung_task.c: allow to set checking interval separately from timeout 2018-08-22 10:52:47 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
arch module: use relative references for __ksymtab entries 2018-08-22 10:52:47 -07:00
block for-4.19/block-20180812 2018-08-14 10:23:25 -07:00
certs Replace magic for trusting the secondary keyring with #define 2018-08-16 09:57:20 -07:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
drivers bcache: use routines from lib/crc64.c for CRC64 calculation 2018-08-22 10:52:48 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs fat: propagate 64-bit inode timestamps 2018-08-22 10:52:50 -07:00
include signal: make get_signal() return bool 2018-08-22 10:52:51 -07:00
init init/main.c: log init process file name 2018-08-22 10:52:49 -07:00
ipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
kernel fork: don't copy inconsistent signal handler state to child 2018-08-22 10:52:51 -07:00
lib lib/test_hexdump.c: fix failure on big endian cpu 2018-08-22 10:52:48 -07:00
mm bdi: use irqsave variant of refcount_dec_and_lock() 2018-08-22 10:52:46 -07:00
net The main things are support for cephx v2 authentication protocol and 2018-08-20 18:26:55 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts checkpatch: DT bindings should be a separate patch 2018-08-22 10:52:49 -07:00
security init: allow initcall tables to be emitted using relative references 2018-08-22 10:52:47 -07:00
sound DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
tools proc: test /proc/thread-self symlink 2018-08-22 10:52:45 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'linus/master' into rdma.git for-next 2018-08-16 14:21:29 -06:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS - New Drivers 2018-08-20 15:38:44 -07:00
Makefile Updates for v4.19: 2018-08-20 18:32:00 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.