cgroup: Take css_set_lock from cgroup_css_sets_empty()

As indicated in the comment above cgroup_css_sets_empty it needs the
css_set_lock. But neither of the 2 call points have it, so rather then fixing
the callers just take the lock inside cgroup_css_sets_empty().

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Change-Id: If7aea71824f6d0e3f2cc6c1ce236c3ae6be2037b
cgroup: Fix use after free of cgrp (cgrp->css_sets)

Running a 3.4 kernel + Fedora-18 (systemd) userland on my Allwinner A10
(arm cortex a8), I'm seeing repeated, reproducable list_del list corruption
errors when build with CONFIG_DEBUG_LIST, and the backtrace always shows
free_css_set_work as the function making the problematic list_del call.

I've tracked this doen to a use after free of the cgrp struct, specifically
of the cgrp->css_sets list_head, which gets cleared by free_css_set_work.

Since free_css_set_work runs form a workqueue, it is possible for it to not be
done with clearing the list when the cgrp gets free-ed. To avoid this the code
adding the links increases cgrp->count, and the freeing code running from the
workqueue decreases cgrp->count *after* doing list_del, and then if the count
goes to 0 calls cgroup_wakeup_rmdir_waiter().

However cgroup_rmdir() is missing a check for cgrp->count != 0, causing it
to still continue with the rmdir (which leads to the free-ing of the cgrp),
before free_css_set_work is done. Sometimes the free-ed memory is re-used
before free_css_set_work gets around to unlinking link->cgrp_link_list,
triggering the list_del list corruption messages.

This patch fixes this by properly checking for cgrp->count != 0 and waiting
for the cgroup_rmdir_waitq in that case.

Change-Id: I9dbc02a0a75d5dffa1b65d67456e00139dea57c3
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
remove cpu-boost in favor of the new cpufreq calculation
sched: Fix migration thread runtime bogosity

commit 8f6189684eb4e85e6c593cd710693f09c944450a upstream.

Make stop scheduler class do the same accounting as other classes,

Migration threads can be caught in the act while doing exec balancing,
leading to the below due to use of unmaintained ->se.exec_start.  The
load that triggered this particular instance was an apparently out of
control heavily threaded application that does system monitoring in
what equated to an exec bomb, with one of the VERY frequently migrated
tasks being ps.

%CPU   PID USER     CMD
99.3    45 root     [migration/10]
97.7    53 root     [migration/12]
97.0    57 root     [migration/13]
90.1    49 root     [migration/11]
89.6    65 root     [migration/15]
88.7    17 root     [migration/3]
80.4    37 root     [migration/8]
78.1    41 root     [migration/9]
44.2    13 root     [migration/2]

Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344051854.6739.19.camel@marge.simpson.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2 in futex_requeue(..., requeue_pi=1)

If uaddr == uaddr2, then we have broken the rule of only requeueing
from a non-pi futex to a pi futex with this call. If we attempt this,
then dangling pointers may be left for rt_waiter resulting in an
exploitable condition.

This change brings futex_requeue() into line with
futex_wait_requeue_pi() which performs the same check as per commit
6f7b0a2a5 (futex: Forbid uaddr == uaddr2 in futex_wait_requeue_pi())

[ tglx: Compare the resulting keys as well, as uaddrs might be
  	different depending on the mapping ]

Fixes CVE-2014-3153.

Reported-by: Pinkie Pie
Signed-off-by: Will Drewry <wad@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
futex: Validate atomic acquisition in futex_lock_pi_atomic()

We need to protect the atomic acquisition in the kernel against rogue
user space which sets the user space futex to 0, so the kernel side
acquisition succeeds while there is existing state in the kernel
associated to the real owner.

Verify whether the futex has waiters associated with kernel state. If
it has, return -EINVAL. The state is corrupted already, so no point in
cleaning it up. Subsequent calls will fail as well. Not our problem.

[ tglx: Use futex_top_waiter() and explain why we do not need to try
  	restoring the already corrupted user space state. ]

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Drewry <wad@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
futex: Always cleanup owner tid in unlock_pi

If the owner died bit is set at futex_unlock_pi, we currently do not
cleanup the user space futex. So the owner TID of the current owner
(the unlocker) persists. That's observable inconsistant state,
especially when the ownership of the pi state got transferred.

Clean it up unconditionally.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: stable@vger.kernel.org
futex: Make lookup_pi_state more robust

The current implementation of lookup_pi_state has ambigous handling of
the TID value 0 in the user space futex. We can get into the kernel
even if the TID value is 0, because either there is a stale waiters
bit or the owner died bit is set or we are called from the requeue_pi
path or from user space just for fun.

The current code avoids an explicit sanity check for pid = 0 in case
that kernel internal state (waiters) are found for the user space
address. This can lead to state leakage and worse under some
circumstances.

Handle the cases explicit:

     Waiter | pi_state | pi->owner | uTID      | uODIED | ?

[1]  NULL   | ---      | ---       | 0         | 0/1    | Valid
[2]  NULL   | ---      | ---       | >0        | 0/1    | Valid

[3]  Found  | NULL     | --        | Any       | 0/1    | Invalid

[4]  Found  | Found    | NULL      | 0         | 1      | Valid
[5]  Found  | Found    | NULL      | >0        | 1      | Invalid

[6]  Found  | Found    | task      | 0         | 1      | Valid

[7]  Found  | Found    | NULL      | Any       | 0      | Invalid

[8]  Found  | Found    | task      | ==taskTID | 0/1    | Valid
[9]  Found  | Found    | task      | 0         | 0      | Invalid
[10] Found  | Found    | task      | !=taskTID | 0/1    | Invalid

[1]  Indicates that the kernel can acquire the futex atomically. We
     came came here due to a stale FUTEX_WAITERS/FUTEX_OWNER_DIED bit.

[2]  Valid, if TID does not belong to a kernel thread. If no matching
     thread is found then it indicates that the owner TID has died.

[3]  Invalid. The waiter is queued on a non PI futex

[4]  Valid state after exit_robust_list(), which sets the user space
     value to FUTEX_WAITERS | FUTEX_OWNER_DIED.

[5]  The user space value got manipulated between exit_robust_list()
     and exit_pi_state_list()

[6]  Valid state after exit_pi_state_list() which sets the new owner in
     the pi_state but cannot access the user space value.

[7]  pi_state->owner can only be NULL when the OWNER_DIED bit is set.

[8]  Owner and user space value match

[9]  There is no transient state which sets the user space TID to 0
     except exit_robust_list(), but this is indicated by the
     FUTEX_OWNER_DIED bit. See [4]

[10] There is no transient state which leaves owner and user space
     TID out of sync.

Backport to 3.13
  conflicts: kernel/futex.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: stable@vger.kernel.org