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A mirror of the official Linux kernel repository just in case
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Stephen Smalley 0c461cb727 selinux: fix off-by-one in setprocattr 
SELinux tries to support setting/clearing of /proc/pid/attr attributes
from the shell by ignoring terminating newlines and treating an
attribute value that begins with a NUL or newline as an attempt to
clear the attribute.  However, the test for clearing attributes has
always been wrong; it has an off-by-one error, and this could further
lead to reading past the end of the allocated buffer since commit
bb646cdb12 ("proc_pid_attr_write():
switch to memdup_user()").  Fix the off-by-one error.

Even with this fix, setting and clearing /proc/pid/attr attributes
from the shell is not straightforward since the interface does not
support multiple write() calls (so shells that write the value and
newline separately will set and then immediately clear the attribute,
requiring use of echo -n to set the attribute), whereas trying to use
echo -n "" to clear the attribute causes the shell to skip the
write() call altogether since POSIX says that a zero-length write
causes no side effects. Thus, one must use echo -n to set and echo
without -n to clear, as in the following example:
$ echo -n unconfined_u:object_r:user_home_t:s0 > /proc/$$/attr/fscreate
$ cat /proc/$$/attr/fscreate
unconfined_u:object_r:user_home_t:s0
$ echo "" > /proc/$$/attr/fscreate
$ cat /proc/$$/attr/fscreate

Note the use of /proc/$$ rather than /proc/self, as otherwise
the cat command will read its own attribute value, not that of the shell.

There are no users of this facility to my knowledge; possibly we
should just get rid of it.

UPDATE: Upon further investigation it appears that a local process
with the process:setfscreate permission can cause a kernel panic as a
result of this bug.  This patch fixes CVE-2017-2618.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: added the update about CVE-2017-2618 to the commit description]
Cc: stable@vger.kernel.org # 3.5: d6ea83ec68
Signed-off-by: Paul Moore <paul@paul-moore.com>

Signed-off-by: James Morris <james.l.morris@oracle.com>
2017-02-08 19:09:53 +11:00
arch ARC: [arcompact] brown paper bag bug in unaligned access delay slot fixup 2017-02-07 10:02:01 -08:00
block blk-mq: Remove unused variable 2017-01-18 15:14:15 -07:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto crypto: algif_aead - Fix kernel panic on list_del 2017-02-03 17:45:48 +08:00
Documentation media fixes for v4.10-rc8 2017-02-06 14:37:55 -08:00
drivers Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-02-07 12:10:57 -08:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs mm: fix KPF_SWAPCACHE in /proc/kpageflags 2017-02-07 12:08:32 -08:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-02-07 12:10:57 -08:00
init kbuild: modversions: add infrastructure for emitting relative CRCs 2017-02-03 08:28:25 -08:00
ipc ipc/sem.c: fix incorrect sem_lock pairing 2017-01-10 18:31:55 -08:00
kernel Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-02-04 12:18:01 -08:00
lib mm: do not export ioremap_page_range symbol for external module 2017-01-24 16:26:14 -08:00
mm mm, fs: check for fatal signals in do_generic_file_read() 2017-02-03 14:13:19 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-02-07 12:10:57 -08:00
samples bpf: fix samples xdp_tx_iptunnel and tc_l2_redirect with fake KBUILD_MODNAME 2017-01-20 12:04:07 -05:00
scripts kbuild: modversions: add infrastructure for emitting relative CRCs 2017-02-03 08:28:25 -08:00
security selinux: fix off-by-one in setprocattr 2017-02-08 19:09:53 +11:00
sound ASoC: Fixes for v4.10 2017-01-11 19:49:27 +01:00
tools Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-02-02 12:54:45 -08:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt KVM/ARM updates for 4.10-rc4 2017-01-17 15:04:59 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
.mailmap mailmap: add codeaurora.org names for nameless email commits 2017-01-10 18:31:55 -08:00
COPYING
CREDITS CREDITS: Remove outdated address information 2016-12-21 15:21:29 -08:00
Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS virtio, vhost: last minute fixes 2017-02-03 15:43:30 -08:00
Makefile Linux 4.10-rc7 2017-02-05 15:10:58 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.