commit 56c91a1843 upstream.
Function kernel_kexec() is called with lock system_transition_mutex
held in reboot system call. While inside kernel_kexec(), it will
acquire system_transition_mutex agin. This will lead to dead lock.
The dead lock should be easily triggered, it hasn't caused any
failure report just because the feature 'kexec jump' is almost not
used by anyone as far as I know. An inquiry can be made about who
is using 'kexec jump' and where it's used. Before that, let's simply
remove the lock operation inside CONFIG_KEXEC_JUMP ifdeffery scope.
Fixes: 55f2503c3b ("PM / reboot: Eliminate race between reboot and suspend")
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Pingfan Liu <kernelfans@gmail.com>
Cc: 4.19+ <stable@vger.kernel.org> # 4.19+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit bbeb97464e upstream.
Below race can come, if trace_open and resize of
cpu buffer is running parallely on different cpus
CPUX CPUY
ring_buffer_resize
atomic_read(&buffer->resize_disabled)
tracing_open
tracing_reset_online_cpus
ring_buffer_reset_cpu
rb_reset_cpu
rb_update_pages
remove/insert pages
resetting pointer
This race can cause data abort or some times infinte loop in
rb_remove_pages and rb_insert_pages while checking pages
for sanity.
Take buffer lock to fix this.
Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org
Cc: stable@vger.kernel.org
Fixes: 83f40318da ("ring-buffer: Make removal of ring buffer pages atomic")
Reported-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 34b1a1ce14 upstream
fixup_pi_state_owner() tries to ensure that the state of the rtmutex,
pi_state and the user space value related to the PI futex are consistent
before returning to user space. In case that the user space value update
faults and the fault cannot be resolved by faulting the page in via
fault_in_user_writeable() the function returns with -EFAULT and leaves
the rtmutex and pi_state owner state inconsistent.
A subsequent futex_unlock_pi() operates on the inconsistent pi_state and
releases the rtmutex despite not owning it which can corrupt the RB tree of
the rtmutex and cause a subsequent kernel stack use after free.
It was suggested to loop forever in fixup_pi_state_owner() if the fault
cannot be resolved, but that results in runaway tasks which is especially
undesired when the problem happens due to a programming error and not due
to malice.
As the user space value cannot be fixed up, the proper solution is to make
the rtmutex and the pi_state consistent so both have the same owner. This
leaves the user space value out of sync. Any subsequent operation on the
futex will fail because the 10th rule of PI futexes (pi_state owner and
user space value are consistent) has been violated.
As a consequence this removes the inept attempts of 'fixing' the situation
in case that the current task owns the rtmutex when returning with an
unresolvable fault by unlocking the rtmutex which left pi_state::owner and
rtmutex::owner out of sync in a different and only slightly less dangerous
way.
Fixes: 1b7558e457 ("futexes: fix fault handling in futex_lock_pi")
Reported-by: gzobqq@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c5cade200a upstream
Updating pi_state::owner is done at several places with the same
code. Provide a function for it and use that at the obvious places.
This is also a preparation for a bug fix to avoid yet another copy of the
same code or alternatively introducing a completely unpenetratable mess of
gotos.
Originally-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 04b79c5520 upstream
If that unexpected case of inconsistent arguments ever happens then the
futex state is left completely inconsistent and the printk is not really
helpful. Replace it with a warning and make the state consistent.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 12bb3f7f1b upstream
In case that futex_lock_pi() was aborted by a signal or a timeout and the
task returned without acquiring the rtmutex, but is the designated owner of
the futex due to a concurrent futex_unlock_pi() fixup_owner() is invoked to
establish consistent state. In that case it invokes fixup_pi_state_owner()
which in turn tries to acquire the rtmutex again. If that succeeds then it
does not propagate this success to fixup_owner() and futex_lock_pi()
returns -EINTR or -ETIMEOUT despite having the futex locked.
Return success from fixup_pi_state_owner() in all cases where the current
task owns the rtmutex and therefore the futex and propagate it correctly
through fixup_owner(). Fixup the other callsite which does not expect a
positive return value.
Fixes: c1e2f0eaf0 ("futex: Avoid violating the 10th rule of futex")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3ef240eaff upstream
Oleg provided the following test case:
int main(void)
{
struct sched_param sp = {};
sp.sched_priority = 2;
assert(sched_setscheduler(0, SCHED_FIFO, &sp) == 0);
int lock = vfork();
if (!lock) {
sp.sched_priority = 1;
assert(sched_setscheduler(0, SCHED_FIFO, &sp) == 0);
_exit(0);
}
syscall(__NR_futex, &lock, FUTEX_LOCK_PI, 0,0,0);
return 0;
}
This creates an unkillable RT process spinning in futex_lock_pi() on a UP
machine or if the process is affine to a single CPU. The reason is:
parent child
set FIFO prio 2
vfork() -> set FIFO prio 1
implies wait_for_child() sched_setscheduler(...)
exit()
do_exit()
....
mm_release()
tsk->futex_state = FUTEX_STATE_EXITING;
exit_futex(); (NOOP in this case)
complete() --> wakes parent
sys_futex()
loop infinite because
tsk->futex_state == FUTEX_STATE_EXITING
The same problem can happen just by regular preemption as well:
task holds futex
...
do_exit()
tsk->futex_state = FUTEX_STATE_EXITING;
--> preemption (unrelated wakeup of some other higher prio task, e.g. timer)
switch_to(other_task)
return to user
sys_futex()
loop infinite as above
Just for the fun of it the futex exit cleanup could trigger the wakeup
itself before the task sets its futex state to DEAD.
To cure this, the handling of the exiting owner is changed so:
- A refcount is held on the task
- The task pointer is stored in a caller visible location
- The caller drops all locks (hash bucket, mmap_sem) and blocks
on task::futex_exit_mutex. When the mutex is acquired then
the exiting task has completed the cleanup and the state
is consistent and can be reevaluated.
This is not a pretty solution, but there is no choice other than returning
an error code to user space, which would break the state consistency
guarantee and open another can of problems including regressions.
For stable backports the preparatory commits ac31c7ff86 .. ba31c1a485
are required as well, but for anything older than 5.3.y the backports are
going to be provided when this hits mainline as the other dependencies for
those kernels are definitely not stable material.
Fixes: 778e9a9c3e ("pi-futex: fix exit races and locking problems")
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Stable Team <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20191106224557.041676471@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ac31c7ff86 upstream
attach_to_pi_owner() returns -EAGAIN for various cases:
- Owner task is exiting
- Futex value has changed
The caller drops the held locks (hash bucket, mmap_sem) and retries the
operation. In case of the owner task exiting this can result in a live
lock.
As a preparatory step for seperating those cases, provide a distinct return
value (EBUSY) for the owner exiting case.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.935606117@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit af8cbda2cf upstream
exec() attempts to handle potentially held futexes gracefully by running
the futex exit handling code like exit() does.
The current implementation has no protection against concurrent incoming
waiters. The reason is that the futex state cannot be set to
FUTEX_STATE_DEAD after the cleanup because the task struct is still active
and just about to execute the new binary.
While its arguably buggy when a task holds a futex over exec(), for
consistency sake the state handling can at least cover the actual futex
exit cleanup section. This provides state consistency protection accross
the cleanup. As the futex state of the task becomes FUTEX_STATE_OK after the
cleanup has been finished, this cannot prevent subsequent attempts to
attach to the task in case that the cleanup was not successfull in mopping
up all leftovers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.753355618@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 18f694385c upstream
Instead of relying on PF_EXITING use an explicit state for the futex exit
and set it in the futex exit function. This moves the smp barrier and the
lock/unlock serialization into the futex code.
As with the DEAD state this is restricted to the exit path as exec
continues to use the same task struct.
This allows to simplify that logic in a next step.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.539409004@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4610ba7ad8 upstream
mm_release() contains the futex exit handling. mm_release() is called from
do_exit()->exit_mm() and from exec()->exec_mm().
In the exit_mm() case PF_EXITING and the futex state is updated. In the
exec_mm() case these states are not touched.
As the futex exit code needs further protections against exit races, this
needs to be split into two functions.
Preparatory only, no functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.240518241@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3d4775df0a upstream
The futex exit handling relies on PF_ flags. That's suboptimal as it
requires a smp_mb() and an ugly lock/unlock of the exiting tasks pi_lock in
the middle of do_exit() to enforce the observability of PF_EXITING in the
futex code.
Add a futex_state member to task_struct and convert the PF_EXITPIDONE logic
over to the new state. The PF_EXITING dependency will be cleaned up in a
later step.
This prepares for handling various futex exit issues later.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.149449274@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ba31c1a485 upstream
The futex exit handling is #ifdeffed into mm_release() which is not pretty
to begin with. But upcoming changes to address futex exit races need to add
more functionality to this exit code.
Split it out into a function, move it into futex code and make the various
futex exit functions static.
Preparatory only and no functional change.
Folded build fix from Borislav.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.049705556@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 01341fbd0d ]
In realtime scenario, We do not want to have interference on the
isolated cpu cores. but when invoking alloc_workqueue() for percpu wq
on the housekeeping cpu, it kick a kworker on the isolated cpu.
alloc_workqueue
pwq_adjust_max_active
wake_up_worker
The comment in pwq_adjust_max_active() said:
"Need to kick a worker after thawed or an unbound wq's
max_active is bumped"
So it is unnecessary to kick a kworker for percpu's wq when invoking
alloc_workqueue(). this patch only kick a worker based on the actual
activation of delayed works.
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 38dc717e97 ]
Apparently there has been a longstanding race between udev/systemd and
the module loader. Currently, the module loader sends a uevent right
after sysfs initialization, but before the module calls its init
function. However, some udev rules expect that the module has
initialized already upon receiving the uevent.
This race has been triggered recently (see link in references) in some
systemd mount unit files. For instance, the configfs module creates the
/sys/kernel/config mount point in its init function, however the module
loader issues the uevent before this happens. sys-kernel-config.mount
expects to be able to mount /sys/kernel/config upon receipt of the
module loading uevent, but if the configfs module has not called its
init function yet, then this directory will not exist and the mount unit
fails. A similar situation exists for sys-fs-fuse-connections.mount, as
the fuse sysfs mount point is created during the fuse module's init
function. If udev is faster than module initialization then the mount
unit would fail in a similar fashion.
To fix this race, delay the module KOBJ_ADD uevent until after the
module has finished calling its init routine.
References: https://github.com/systemd/systemd/issues/17586
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-By: Nicolas Morey-Chaisemartin <nmoreychaisemartin@suse.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5e8ed280da ]
If a module fails to load due to an error in prepare_coming_module(),
the following error handling in load_module() runs with
MODULE_STATE_COMING in module's state. Fix it by correctly setting
MODULE_STATE_GOING under "bug_cleanup" label.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 4615fbc378 ]
When an interrupt allocation fails for N interrupts, it is pretty
common for the error handling code to free the same number of interrupts,
no matter how many interrupts have actually been allocated.
This may result in the domain freeing code to be unexpectedly called
for interrupts that have no mapping in that domain. Things end pretty
badly.
Instead, add some checks to irq_domain_free_irqs_hierarchy() to make sure
that thiss does not follow the hierarchy if no mapping exists for a given
interrupt.
Fixes: 6a6544e520 ("genirq/irqdomain: Remove auto-recursive hierarchy support")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201129135551.396777-1-maz@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 345a957fcc ]
do_sched_yield() invokes schedule() with interrupts disabled which is
not allowed. This goes back to the pre git era to commit a6efb709806c
("[PATCH] irqlock patch 2.5.27-H6") in the history tree.
Reenable interrupts and remove the misleading comment which "explains" it.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/87r1pt7y5c.fsf@nanos.tec.linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a57415f5d1 ]
When change sched_rt_{runtime, period}_us, we validate that the new
settings should at least accommodate the currently allocated -dl
bandwidth:
sched_rt_handler()
--> sched_dl_bandwidth_validate()
{
new_bw = global_rt_runtime()/global_rt_period();
for_each_possible_cpu(cpu) {
dl_b = dl_bw_of(cpu);
if (new_bw < dl_b->total_bw) <-------
ret = -EBUSY;
}
}
But under CONFIG_SMP, dl_bw is per root domain , but not per CPU,
dl_b->total_bw is the allocated bandwidth of the whole root domain.
Instead, we should compare dl_b->total_bw against "cpus*new_bw",
where 'cpus' is the number of CPUs of the root domain.
Also, below annotation(in kernel/sched/sched.h) implied implementation
only appeared in SCHED_DEADLINE v2[1], then deadline scheduler kept
evolving till got merged(v9), but the annotation remains unchanged,
meaningless and misleading, update it.
* With respect to SMP, the bandwidth is given on a per-CPU basis,
* meaning that:
* - dl_bw (< 100%) is the bandwidth of the system (group) on each CPU;
* - dl_total_bw array contains, in the i-eth element, the currently
* allocated bandwidth on the i-eth CPU.
[1]: https://lore.kernel.org/lkml/1267385230.13676.101.camel@Palantir/
Fixes: 332ac17ef5 ("sched/deadline: Add bandwidth management for SCHED_DEADLINE tasks")
Signed-off-by: Peng Liu <iwtbavbm@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/db6bbda316048cda7a1bbc9571defde193a8d67e.1602171061.git.iwtbavbm@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit bcee527895 upstream.
When the instances were able to use their own options, the userstacktrace
option was left hardcoded for the top level. This made the instance
userstacktrace option bascially into a nop, and will confuse users that set
it, but nothing happens (I was confused when it happened to me!)
Cc: stable@vger.kernel.org
Fixes: 16270145ce ("tracing: Add trace options for core options to instances")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4c75b0ff4e upstream.
On powerpc, kprobe-direct.tc triggered FTRACE_WARN_ON() in
ftrace_get_addr_new() followed by the below message:
Bad trampoline accounting at: 000000004222522f (wake_up_process+0xc/0x20) (f0000001)
The set of steps leading to this involved:
- modprobe ftrace-direct-too
- enable_probe
- modprobe ftrace-direct
- rmmod ftrace-direct <-- trigger
The problem turned out to be that we were not updating flags in the
ftrace record properly. From the above message about the trampoline
accounting being bad, it can be seen that the ftrace record still has
FTRACE_FL_TRAMP set though ftrace-direct module is going away. This
happens because we are checking if any ftrace_ops has the
FTRACE_FL_TRAMP flag set _before_ updating the filter hash.
The fix for this is to look for any _other_ ftrace_ops that also needs
FTRACE_FL_TRAMP.
Link: https://lkml.kernel.org/r/56c113aa9c3e10c19144a36d9684c7882bf09af5.1606412433.git.naveen.n.rao@linux.vnet.ibm.com
Cc: stable@vger.kernel.org
Fixes: a124692b69 ("ftrace: Enable trampoline when rec count returns back to one")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 310e3a4b5a upstream.
This patch reverts commit 978defee11 ("tracing: Do a WARN_ON()
if start_thread() in hwlat is called when thread exists")
.start hook can be legally called several times if according
tracer is stopped
screen window 1
[root@localhost ~]# echo 1 > /sys/kernel/tracing/events/kmem/kfree/enable
[root@localhost ~]# echo 1 > /sys/kernel/tracing/options/pause-on-trace
[root@localhost ~]# less -F /sys/kernel/tracing/trace
screen window 2
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo hwlat > /sys/kernel/debug/tracing/current_tracer
[root@localhost ~]# echo 1 > /sys/kernel/debug/tracing/tracing_on
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo 2 > /sys/kernel/debug/tracing/tracing_on
triggers warning in dmesg:
WARNING: CPU: 3 PID: 1403 at kernel/trace/trace_hwlat.c:371 hwlat_tracer_start+0xc9/0xd0
Link: https://lkml.kernel.org/r/bd4d3e70-400d-9c82-7b73-a2d695e86b58@virtuozzo.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 978defee11 ("tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8b92c4ff44 upstream.
Patch series "fix parsing of reboot= cmdline", v3.
The parsing of the reboot= cmdline has two major errors:
- a missing bound check can crash the system on reboot
- parsing of the cpu number only works if specified last
Fix both.
This patch (of 2):
This reverts commit 616feab753.
kstrtoint() and simple_strtoul() have a subtle difference which makes
them non interchangeable: if a non digit character is found amid the
parsing, the former will return an error, while the latter will just
stop parsing, e.g. simple_strtoul("123xyx") = 123.
The kernel cmdline reboot= argument allows to specify the CPU used for
rebooting, with the syntax `s####` among the other flags, e.g.
"reboot=warm,s31,force", so if this flag is not the last given, it's
silently ignored as well as the subsequent ones.
Fixes: 616feab753 ("kernel/reboot.c: convert simple_strtoul to kstrtoint")
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201103214025.116799-2-mcroce@linux.microsoft.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[sudip: use reboot_mode instead of mode]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f91072ed1b upstream.
There's a possible race in perf_mmap_close() when checking ring buffer's
mmap_count refcount value. The problem is that the mmap_count check is
not atomic because we call atomic_dec() and atomic_read() separately.
perf_mmap_close:
...
atomic_dec(&rb->mmap_count);
...
if (atomic_read(&rb->mmap_count))
goto out_put;
<ring buffer detach>
free_uid
out_put:
ring_buffer_put(rb); /* could be last */
The race can happen when we have two (or more) events sharing same ring
buffer and they go through atomic_dec() and then they both see 0 as refcount
value later in atomic_read(). Then both will go on and execute code which
is meant to be run just once.
The code that detaches ring buffer is probably fine to be executed more
than once, but the problem is in calling free_uid(), which will later on
demonstrate in related crashes and refcount warnings, like:
refcount_t: addition on 0; use-after-free.
...
RIP: 0010:refcount_warn_saturate+0x6d/0xf
...
Call Trace:
prepare_creds+0x190/0x1e0
copy_creds+0x35/0x172
copy_process+0x471/0x1a80
_do_fork+0x83/0x3a0
__do_sys_wait4+0x83/0x90
__do_sys_clone+0x85/0xa0
do_syscall_64+0x5b/0x1e0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Using atomic decrease and check instead of separated calls.
Tested-by: Michael Petlan <mpetlan@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Wade Mealing <wmealing@redhat.com>
Fixes: 9bb5d40cd9 ("perf: Fix mmap() accounting hole");
Link: https://lore.kernel.org/r/20200916115311.GE2301783@krava
[sudip: used ring_buffer]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c51f8f88d7 upstream.
Non-cryptographic PRNGs may have great statistical properties, but
are usually trivially predictable to someone who knows the algorithm,
given a small sample of their output. An LFSR like prandom_u32() is
particularly simple, even if the sample is widely scattered bits.
It turns out the network stack uses prandom_u32() for some things like
random port numbers which it would prefer are *not* trivially predictable.
Predictability led to a practical DNS spoofing attack. Oops.
This patch replaces the LFSR with a homebrew cryptographic PRNG based
on the SipHash round function, which is in turn seeded with 128 bits
of strong random key. (The authors of SipHash have *not* been consulted
about this abuse of their algorithm.) Speed is prioritized over security;
attacks are rare, while performance is always wanted.
Replacing all callers of prandom_u32() is the quick fix.
Whether to reinstate a weaker PRNG for uses which can tolerate it
is an open question.
Commit f227e3ec3b ("random32: update the net random state on interrupt
and activity") was an earlier attempt at a solution. This patch replaces
it.
Reported-by: Amit Klein <aksecurity@gmail.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tytso@mit.edu
Cc: Florian Westphal <fw@strlen.de>
Cc: Marc Plumb <lkml.mplumb@gmail.com>
Fixes: f227e3ec3b ("random32: update the net random state on interrupt and activity")
Signed-off-by: George Spelvin <lkml@sdf.org>
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
[ willy: partial reversal of f227e3ec3b5c; moved SIPROUND definitions
to prandom.h for later use; merged George's prandom_seed() proposal;
inlined siprand_u32(); replaced the net_rand_state[] array with 4
members to fix a build issue; cosmetic cleanups to make checkpatch
happy; fixed RANDOM32_SELFTEST build ]
[wt: backported to 4.19 -- various context adjustments]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e9696d259d upstream.
kernel/dma/swiotlb.c:swiotlb_init gets called first and tries to
allocate a buffer for the swiotlb. It does so by calling
memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
If the allocation must fail, no_iotlb_memory is set.
Later during initialization swiotlb-xen comes in
(drivers/xen/swiotlb-xen.c:xen_swiotlb_init) and given that io_tlb_start
is != 0, it thinks the memory is ready to use when actually it is not.
When the swiotlb is actually needed, swiotlb_tbl_map_single gets called
and since no_iotlb_memory is set the kernel panics.
Instead, if swiotlb-xen.c:xen_swiotlb_init knew the swiotlb hadn't been
initialized, it would do the initialization itself, which might still
succeed.
Fix the panic by setting io_tlb_start to 0 on swiotlb initialization
failure, and also by setting no_iotlb_memory to false on swiotlb
initialization success.
Fixes: ac2cbab21f ("x86: Don't panic if can not alloc buffer for swiotlb")
Reported-by: Elliott Mitchell <ehem+xen@m5p.com>
Tested-by: Elliott Mitchell <ehem+xen@m5p.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 77f6ab8b77 upstream.
Coredump logics needs to report not only the registers of the dumping
thread, but (since 2.5.43) those of other threads getting killed.
Doing that might require extra state saved on the stack in asm glue at
kernel entry; signal delivery logics does that (we need to be able to
save sigcontext there, at the very least) and so does seccomp.
That covers all callers of do_coredump(). Secondary threads get hit with
SIGKILL and caught as soon as they reach exit_mm(), which normally happens
in signal delivery, so those are also fine most of the time. Unfortunately,
it is possible to end up with secondary zapped when it has already entered
exit(2) (or, worse yet, is oopsing). In those cases we reach exit_mm()
when mm->core_state is already set, but the stack contents is not what
we would have in signal delivery.
At least on two architectures (alpha and m68k) it leads to infoleaks - we
end up with a chunk of kernel stack written into coredump, with the contents
consisting of normal C stack frames of the call chain leading to exit_mm()
instead of the expected copy of userland registers. In case of alpha we
leak 312 bytes of stack. Other architectures (including the regset-using
ones) might have similar problems - the normal user of regsets is ptrace
and the state of tracee at the time of such calls is special in the same
way signal delivery is.
Note that had the zapper gotten to the exiting thread slightly later,
it wouldn't have been included into coredump anyway - we skip the threads
that have already cleared their ->mm. So let's pretend that zapper always
loses the race. IOW, have exit_mm() only insert into the dumper list if
we'd gotten there from handling a fatal signal[*]
As the result, the callers of do_exit() that have *not* gone through get_signal()
are not seen by coredump logics as secondary threads. Which excludes voluntary
exit()/oopsen/traps/etc. The dumper thread itself is unaffected by that,
so seccomp is fine.
[*] originally I intended to add a new flag in tsk->flags, but ebiederman pointed
out that PF_SIGNALED is already doing just what we need.
Cc: stable@vger.kernel.org
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5167c506d6 upstream.
Suspend to IDLE invokes tick_unfreeze() on resume. tick_unfreeze() on the
first resuming CPU resumes timekeeping, which also has the side effect of
resetting the softlockup watchdog on this CPU.
But on the secondary CPUs the watchdog is not reset in the resume /
unfreeze() path, which can result in false softlockup warnings on those
CPUs depending on the time spent in suspend.
Prevent this by clearing the softlock watchdog in the unfreeze path also
on the secondary resuming CPUs.
[ tglx: Massaged changelog ]
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200110083902.27276-1-chunyan.zhang@unisoc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit cb47755725 ]
UBSAN reports:
Undefined behaviour in ./include/linux/time64.h:127:27
signed integer overflow:
17179869187 * 1000000000 cannot be represented in type 'long long int'
Call Trace:
timespec64_to_ns include/linux/time64.h:127 [inline]
set_cpu_itimer+0x65c/0x880 kernel/time/itimer.c:180
do_setitimer+0x8e/0x740 kernel/time/itimer.c:245
__x64_sys_setitimer+0x14c/0x2c0 kernel/time/itimer.c:336
do_syscall_64+0xa1/0x540 arch/x86/entry/common.c:295
Commit bd40a17576 ("y2038: itimer: change implementation to timespec64")
replaced the original conversion which handled time clamping correctly with
timespec64_to_ns() which has no overflow protection.
Fix it in timespec64_to_ns() as this is not necessarily limited to the
usage in itimers.
[ tglx: Added comment and adjusted the fixes tag ]
Fixes: 361a3bf005 ("time64: Add time64.h header and define struct timespec64")
Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1598952616-6416-1-git-send-email-prime.zeng@hisilicon.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 7bdb157cde upstream.
As shown through runtime testing, the "filename" allocation is not
always freed in perf_event_parse_addr_filter().
There are three possible ways that this could happen:
- It could be allocated twice on subsequent iterations through the loop,
- or leaked on the success path,
- or on the failure path.
Clean up the code flow to make it obvious that 'filename' is always
freed in the reallocation path and in the two return paths as well.
We rely on the fact that kfree(NULL) is NOP and filename is initialized
with NULL.
This fixes the leak. No other side effects expected.
[ Dan Carpenter: cleaned up the code flow & added a changelog. ]
[ Ingo Molnar: updated the changelog some more. ]
Fixes: 375637bc52 ("perf/core: Introduce address range filtering")
Signed-off-by: "kiyin(尹亮)" <kiyin@tencent.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "Srivatsa S. Bhat" <srivatsa@csail.mit.edu>
Cc: Anthony Liguori <aliguori@amazon.com>
--
kernel/events/core.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 9f5d1c336a upstream.
Gratian managed to trigger the BUG_ON(!newowner) in fixup_pi_state_owner().
This is one possible chain of events leading to this:
Task Prio Operation
T1 120 lock(F)
T2 120 lock(F) -> blocks (top waiter)
T3 50 (RT) lock(F) -> boosts T1 and blocks (new top waiter)
XX timeout/ -> wakes T2
signal
T1 50 unlock(F) -> wakes T3 (rtmutex->owner == NULL, waiter bit is set)
T2 120 cleanup -> try_to_take_mutex() fails because T3 is the top waiter
and the lower priority T2 cannot steal the lock.
-> fixup_pi_state_owner() sees newowner == NULL -> BUG_ON()
The comment states that this is invalid and rt_mutex_real_owner() must
return a non NULL owner when the trylock failed, but in case of a queued
and woken up waiter rt_mutex_real_owner() == NULL is a valid transient
state. The higher priority waiter has simply not yet managed to take over
the rtmutex.
The BUG_ON() is therefore wrong and this is just another retry condition in
fixup_pi_state_owner().
Drop the locks, so that T3 can make progress, and then try the fixup again.
Gratian provided a great analysis, traces and a reproducer. The analysis is
to the point, but it confused the hell out of that tglx dude who had to
page in all the futex horrors again. Condensed version is above.
[ tglx: Wrote comment and changelog ]
Fixes: c1e2f0eaf0 ("futex: Avoid violating the 10th rule of futex")
Reported-by: Gratian Crisan <gratian.crisan@ni.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87a6w6x7bb.fsf@ni.com
Link: https://lore.kernel.org/r/87sg9pkvf7.fsf@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c1acb4ac1a upstream.
The nesting count of trace_printk allows for 4 levels of nesting. The
nesting counter starts at zero and is incremented before being used to
retrieve the current context's buffer. But the index to the buffer uses the
nesting counter after it was incremented, and not its original number,
which in needs to do.
Link: https://lkml.kernel.org/r/20201029161905.4269-1-hqjagain@gmail.com
Cc: stable@vger.kernel.org
Fixes: 3d9622c12c ("tracing: Add barrier to trace_printk() buffer nesting modification")
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
