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Filename Latest commit message Latest commit date
Peter Zijlstra 153fbd1226 futex: Fix more put_pi_state() vs. exit_pi_state_list() races
Dmitry (through syzbot) reported being able to trigger the WARN in
get_pi_state() and a use-after-free on:

	raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);

Both are due to this race:

  exit_pi_state_list()				put_pi_state()

  lock(&curr->pi_lock)
  while() {
	pi_state = list_first_entry(head);
	hb = hash_futex(&pi_state->key);
	unlock(&curr->pi_lock);

						dec_and_test(&pi_state->refcount);

	lock(&hb->lock)
	lock(&pi_state->pi_mutex.wait_lock)	// uaf if pi_state free'd
	lock(&curr->pi_lock);

	....

	unlock(&curr->pi_lock);
	get_pi_state();				// WARN; refcount==0

The problem is we take the reference count too late, and don't allow it
being 0. Fix it by using inc_not_zero() and simply retrying the loop
when we fail to get a refcount. In that case put_pi_state() should
remove the entry from the list.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Gratian Crisan <gratian.crisan@ni.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: dvhart@infradead.org
Cc: syzbot <bot+2af19c9e1ffe4d4ee1d16c56ae7580feaee75765@syzkaller.appspotmail.com>
Cc: syzkaller-bugs@googlegroups.com
Cc: <stable@vger.kernel.org>
Fixes: c74aef2d06 ("futex: Fix pi_state->owner serialization")
Link: http://lkml.kernel.org/r/20171031101853.xpfh72y643kdfhjs@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-01 09:05:00 +01:00
arch Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-10-30 09:31:15 -07:00
block
certs
crypto
Documentation Kbuild fixes for v4.14 (2nd) 2017-10-28 11:01:57 -07:00
drivers MMC host: 2017-10-30 09:41:54 -07:00
firmware
fs Various SMB3 fixes for 4.14 and stable 2017-10-28 08:39:35 -07:00
include PM / QoS: Fix default runtime_pm device resume latency 2017-10-30 10:54:57 +01:00
init
ipc
kernel futex: Fix more put_pi_state() vs. exit_pi_state_list() races 2017-11-01 09:05:00 +01:00
lib Mark 'ioremap_page_range()' as possibly sleeping 2017-10-30 10:09:56 -07:00
mm
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-29 08:11:49 -07:00
samples Fix tracing sample code warning. 2017-10-27 20:35:31 -07:00
scripts Kbuild fixes for v4.14 (2nd) 2017-10-28 11:01:57 -07:00
security Revert "apparmor: add base infastructure for socket mediation" 2017-10-26 19:35:35 +02:00
sound ALSA: hda - fix headset mic problem for Dell machines with alc236 2017-10-24 14:32:24 +02:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-29 08:11:49 -07:00
usr
virt
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS xen: fixes for 4.14-rc7 2017-10-27 20:41:05 -07:00
Makefile Linux 4.14-rc7 2017-10-29 13:58:38 -07:00
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.