commit a88afa46b8 upstream.
When the kernel is configured to use the Thumb-2 instruction set
"suspend-to-memory" fails to resume. Observed on a Colibri iMX6ULL
(i.MX 6ULL) and Apalis iMX6 (i.MX 6Q).
It looks like the CPU resumes unconditionally in ARM instruction mode
and then chokes on the presented Thumb-2 code it should execute.
Fix this by using the arm instruction set for all code in
suspend-imx6.S.
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Fixes: df595746fa ("ARM: imx: add suspend in ocram support for i.mx6q")
Acked-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0549cd67b0 upstream.
This is inline with the specification described in blkif.h:
* discard-granularity: should be set to the physical block size if
node is not present.
* discard-alignment, discard-secure: should be set to 0 if node not
present.
This was detected as QEMU would only create the discard-granularity
node but not discard-alignment, and thus the setup done in
blkfront_setup_discard would fail.
Fix blkfront_setup_discard to not fail on missing nodes, and also fix
blkif_set_queue_limits to set the discard granularity to the physical
block size if none is specified in xenbus.
Fixes: ed30bf317c ('xen-blkfront: Handle discard requests.')
Reported-by: Arthur Borsboom <arthurborsboom@gmail.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Tested-By: Arthur Borsboom <arthurborsboom@gmail.com>
Link: https://lore.kernel.org/r/20210119105727.95173-1-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 27af8e2c90 upstream.
We have the following potential deadlock condition:
========================================================
WARNING: possible irq lock inversion dependency detected
5.10.0-rc2+ #25 Not tainted
--------------------------------------------------------
swapper/3/0 just changed the state of lock:
ffff8880063bd618 (&host->lock){-...}-{2:2}, at: ata_bmdma_interrupt+0x27/0x200
but this lock took another, HARDIRQ-READ-unsafe lock in the past:
(&trig->leddev_list_lock){.+.?}-{2:2}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&trig->leddev_list_lock);
local_irq_disable();
lock(&host->lock);
lock(&trig->leddev_list_lock);
<Interrupt>
lock(&host->lock);
*** DEADLOCK ***
no locks held by swapper/3/0.
the shortest dependencies between 2nd lock and 1st lock:
-> (&trig->leddev_list_lock){.+.?}-{2:2} ops: 46 {
HARDIRQ-ON-R at:
lock_acquire+0x15f/0x420
_raw_read_lock+0x42/0x90
led_trigger_event+0x2b/0x70
rfkill_global_led_trigger_worker+0x94/0xb0
process_one_work+0x240/0x560
worker_thread+0x58/0x3d0
kthread+0x151/0x170
ret_from_fork+0x1f/0x30
IN-SOFTIRQ-R at:
lock_acquire+0x15f/0x420
_raw_read_lock+0x42/0x90
led_trigger_event+0x2b/0x70
kbd_bh+0x9e/0xc0
tasklet_action_common.constprop.0+0xe9/0x100
tasklet_action+0x22/0x30
__do_softirq+0xcc/0x46d
run_ksoftirqd+0x3f/0x70
smpboot_thread_fn+0x116/0x1f0
kthread+0x151/0x170
ret_from_fork+0x1f/0x30
SOFTIRQ-ON-R at:
lock_acquire+0x15f/0x420
_raw_read_lock+0x42/0x90
led_trigger_event+0x2b/0x70
rfkill_global_led_trigger_worker+0x94/0xb0
process_one_work+0x240/0x560
worker_thread+0x58/0x3d0
kthread+0x151/0x170
ret_from_fork+0x1f/0x30
INITIAL READ USE at:
lock_acquire+0x15f/0x420
_raw_read_lock+0x42/0x90
led_trigger_event+0x2b/0x70
rfkill_global_led_trigger_worker+0x94/0xb0
process_one_work+0x240/0x560
worker_thread+0x58/0x3d0
kthread+0x151/0x170
ret_from_fork+0x1f/0x30
}
... key at: [<ffffffff83da4c00>] __key.0+0x0/0x10
... acquired at:
_raw_read_lock+0x42/0x90
led_trigger_blink_oneshot+0x3b/0x90
ledtrig_disk_activity+0x3c/0xa0
ata_qc_complete+0x26/0x450
ata_do_link_abort+0xa3/0xe0
ata_port_freeze+0x2e/0x40
ata_hsm_qc_complete+0x94/0xa0
ata_sff_hsm_move+0x177/0x7a0
ata_sff_pio_task+0xc7/0x1b0
process_one_work+0x240/0x560
worker_thread+0x58/0x3d0
kthread+0x151/0x170
ret_from_fork+0x1f/0x30
-> (&host->lock){-...}-{2:2} ops: 69 {
IN-HARDIRQ-W at:
lock_acquire+0x15f/0x420
_raw_spin_lock_irqsave+0x52/0xa0
ata_bmdma_interrupt+0x27/0x200
__handle_irq_event_percpu+0xd5/0x2b0
handle_irq_event+0x57/0xb0
handle_edge_irq+0x8c/0x230
asm_call_irq_on_stack+0xf/0x20
common_interrupt+0x100/0x1c0
asm_common_interrupt+0x1e/0x40
native_safe_halt+0xe/0x10
arch_cpu_idle+0x15/0x20
default_idle_call+0x59/0x1c0
do_idle+0x22c/0x2c0
cpu_startup_entry+0x20/0x30
start_secondary+0x11d/0x150
secondary_startup_64_no_verify+0xa6/0xab
INITIAL USE at:
lock_acquire+0x15f/0x420
_raw_spin_lock_irqsave+0x52/0xa0
ata_dev_init+0x54/0xe0
ata_link_init+0x8b/0xd0
ata_port_alloc+0x1f1/0x210
ata_host_alloc+0xf1/0x130
ata_host_alloc_pinfo+0x14/0xb0
ata_pci_sff_prepare_host+0x41/0xa0
ata_pci_bmdma_prepare_host+0x14/0x30
piix_init_one+0x21f/0x600
local_pci_probe+0x48/0x80
pci_device_probe+0x105/0x1c0
really_probe+0x221/0x490
driver_probe_device+0xe9/0x160
device_driver_attach+0xb2/0xc0
__driver_attach+0x91/0x150
bus_for_each_dev+0x81/0xc0
driver_attach+0x1e/0x20
bus_add_driver+0x138/0x1f0
driver_register+0x91/0xf0
__pci_register_driver+0x73/0x80
piix_init+0x1e/0x2e
do_one_initcall+0x5f/0x2d0
kernel_init_freeable+0x26f/0x2cf
kernel_init+0xe/0x113
ret_from_fork+0x1f/0x30
}
... key at: [<ffffffff83d9fdc0>] __key.6+0x0/0x10
... acquired at:
__lock_acquire+0x9da/0x2370
lock_acquire+0x15f/0x420
_raw_spin_lock_irqsave+0x52/0xa0
ata_bmdma_interrupt+0x27/0x200
__handle_irq_event_percpu+0xd5/0x2b0
handle_irq_event+0x57/0xb0
handle_edge_irq+0x8c/0x230
asm_call_irq_on_stack+0xf/0x20
common_interrupt+0x100/0x1c0
asm_common_interrupt+0x1e/0x40
native_safe_halt+0xe/0x10
arch_cpu_idle+0x15/0x20
default_idle_call+0x59/0x1c0
do_idle+0x22c/0x2c0
cpu_startup_entry+0x20/0x30
start_secondary+0x11d/0x150
secondary_startup_64_no_verify+0xa6/0xab
This lockdep splat is reported after:
commit e918188611 ("locking: More accurate annotations for read_lock()")
To clarify:
- read-locks are recursive only in interrupt context (when
in_interrupt() returns true)
- after acquiring host->lock in CPU1, another cpu (i.e. CPU2) may call
write_lock(&trig->leddev_list_lock) that would be blocked by CPU0
that holds trig->leddev_list_lock in read-mode
- when CPU1 (ata_ac_complete()) tries to read-lock
trig->leddev_list_lock, it would be blocked by the write-lock waiter
on CPU2 (because we are not in interrupt context, so the read-lock is
not recursive)
- at this point if an interrupt happens on CPU0 and
ata_bmdma_interrupt() is executed it will try to acquire host->lock,
that is held by CPU1, that is currently blocked by CPU2, so:
* CPU0 blocked by CPU1
* CPU1 blocked by CPU2
* CPU2 blocked by CPU0
*** DEADLOCK ***
The deadlock scenario is better represented by the following schema
(thanks to Boqun Feng <boqun.feng@gmail.com> for the schema and the
detailed explanation of the deadlock condition):
CPU 0: CPU 1: CPU 2:
----- ----- -----
led_trigger_event():
read_lock(&trig->leddev_list_lock);
<workqueue>
ata_hsm_qc_complete():
spin_lock_irqsave(&host->lock);
write_lock(&trig->leddev_list_lock);
ata_port_freeze():
ata_do_link_abort():
ata_qc_complete():
ledtrig_disk_activity():
led_trigger_blink_oneshot():
read_lock(&trig->leddev_list_lock);
// ^ not in in_interrupt() context, so could get blocked by CPU 2
<interrupt>
ata_bmdma_interrupt():
spin_lock_irqsave(&host->lock);
Fix by using read_lock_irqsave/irqrestore() in led_trigger_event(), so
that no interrupt can happen in between, preventing the deadlock
condition.
Apply the same change to led_trigger_blink_setup() as well, since the
same deadlock scenario can also happen in power_supply_update_bat_leds()
-> led_trigger_blink() -> led_trigger_blink_setup() (workqueue context),
and potentially prevent other similar usages.
Link: https://lore.kernel.org/lkml/20201101092614.GB3989@xps-13-7390/
Fixes: eb25cb9956 ("leds: convert IDE trigger to common disk trigger")
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5f46400f7a upstream.
In commit 3499ba8198 ("xen: Fix event channel callback via INTX/GSI")
I reworked the triggering of xenbus_probe().
I tried to simplify things by taking out the workqueue based startup
triggered from wake_waiting(); the somewhat poorly named xenbus IRQ
handler.
I missed the fact that in the XS_LOCAL case (Dom0 starting its own
xenstored or xenstore-stubdom, which happens after the kernel is booted
completely), that IRQ-based trigger is still actually needed.
So... put it back, except more cleanly. By just spawning a xenbus_probe
thread which waits on xb_waitq and runs the probe the first time it
gets woken, just as the workqueue-based hack did.
This is actually a nicer approach for *all* the back ends with different
interrupt methods, and we can switch them all over to that without the
complex conditions for when to trigger it. But not in -rc6. This is
the minimal fix for the regression, although it's a step in the right
direction instead of doing a partial revert and actually putting the
workqueue back. It's also simpler than the workqueue.
Fixes: 3499ba8198 ("xen: Fix event channel callback via INTX/GSI")
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/4c9af052a6e0f6485d1de43f2c38b1461996db99.camel@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: Salvatore Bonaccorso <carnil@debian.org>
Cc: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1f7becf1b7 upstream.
The injection process of smi has two steps:
Qemu KVM
Step1:
cpu->interrupt_request &= \
~CPU_INTERRUPT_SMI;
kvm_vcpu_ioctl(cpu, KVM_SMI)
call kvm_vcpu_ioctl_smi() and
kvm_make_request(KVM_REQ_SMI, vcpu);
Step2:
kvm_vcpu_ioctl(cpu, KVM_RUN, 0)
call process_smi() if
kvm_check_request(KVM_REQ_SMI, vcpu) is
true, mark vcpu->arch.smi_pending = true;
The vcpu->arch.smi_pending will be set true in step2, unfortunately if
vcpu paused between step1 and step2, the kvm_run->immediate_exit will be
set and vcpu has to exit to Qemu immediately during step2 before mark
vcpu->arch.smi_pending true.
During VM migration, Qemu will get the smi pending status from KVM using
KVM_GET_VCPU_EVENTS ioctl at the downtime, then the smi pending status
will be lost.
Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>
Signed-off-by: Shengen Zhuang <zhuangshengen@huawei.com>
Message-Id: <20210118084720.1585-1-jianjay.zhou@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6808965568 upstream.
of_match_node() calls __of_match_node() which loops though the entries of
matches array. It stops when condition:
(matches->name[0] || matches->type[0] || matches->compatible[0]) is
false. Thus, add a null entry at the end of at91_soc_allowed_list[]
array.
Fixes: caab13b496 ("drivers: soc: atmel: Avoid calling at91_soc_init on non AT91 SoCs")
Cc: stable@vger.kernel.org #4.12+
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 36af2d5c44 upstream.
Commit 8765c5ba19 ("ACPI / scan: Rework modalias creation when
"compatible" is present") may create two "MODALIAS=" in one uevent
file if specific conditions are met.
This breaks systemd-udevd, which assumes each "key" in one uevent file
to be unique. The internal implementation of systemd-udevd overwrites
the first MODALIAS with the second one, so its kmod rule doesn't load
the driver for the first MODALIAS.
So if both the ACPI modalias and the OF modalias are present, use the
latter to ensure that there will be only one MODALIAS.
Link: https://github.com/systemd/systemd/pull/18163
Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Fixes: 8765c5ba19 ("ACPI / scan: Rework modalias creation when "compatible" is present")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: 4.1+ <stable@vger.kernel.org> # 4.1+
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b98e762e3d upstream.
When setting up a device, we can krealloc the config->socks array to add
new sockets to the configuration. However if we happen to get a IO
request in at this point even though we aren't setup we could hit a UAF,
as we deref config->socks without any locking, assuming that the
configuration was setup already and that ->socks is safe to access it as
we have a reference on the configuration.
But there's nothing really preventing IO from occurring at this point of
the device setup, we don't want to incur the overhead of a lock to
access ->socks when it will never change while the device is running.
To fix this UAF scenario simply freeze the queue if we are adding
sockets. This will protect us from this particular case without adding
any additional overhead for the normal running case.
Cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1e249cb5b7 upstream.
When lazytime is enabled and an inode is being written due to its
in-memory updated timestamps having expired, either due to a sync() or
syncfs() system call or due to dirtytime_expire_interval having elapsed,
the VFS needs to inform the filesystem so that the filesystem can copy
the inode's timestamps out to the on-disk data structures.
This is done by __writeback_single_inode() calling
mark_inode_dirty_sync(), which then calls ->dirty_inode(I_DIRTY_SYNC).
However, this occurs after __writeback_single_inode() has already
cleared the dirty flags from ->i_state. This causes two bugs:
- mark_inode_dirty_sync() redirties the inode, causing it to remain
dirty. This wastefully causes the inode to be written twice. But
more importantly, it breaks cases where sync_filesystem() is expected
to clean dirty inodes. This includes the FS_IOC_REMOVE_ENCRYPTION_KEY
ioctl (as reported at
https://lore.kernel.org/r/20200306004555.GB225345@gmail.com), as well
as possibly filesystem freezing (freeze_super()).
- Since ->i_state doesn't contain I_DIRTY_TIME when ->dirty_inode() is
called from __writeback_single_inode() for lazytime expiration,
xfs_fs_dirty_inode() ignores the notification. (XFS only cares about
lazytime expirations, and it assumes that i_state will contain
I_DIRTY_TIME during those.) Therefore, lazy timestamps aren't
persisted by sync(), syncfs(), or dirtytime_expire_interval on XFS.
Fix this by moving the call to mark_inode_dirty_sync() to earlier in
__writeback_single_inode(), before the dirty flags are cleared from
i_state. This makes filesystems be properly notified of the timestamp
expiration, and it avoids incorrectly redirtying the inode.
This fixes xfstest generic/580 (which tests
FS_IOC_REMOVE_ENCRYPTION_KEY) when run on ext4 or f2fs with lazytime
enabled. It also fixes the new lazytime xfstest I've proposed, which
reproduces the above-mentioned XFS bug
(https://lore.kernel.org/r/20210105005818.92978-1-ebiggers@kernel.org).
Alternatively, we could call ->dirty_inode(I_DIRTY_SYNC) directly. But
due to the introduction of I_SYNC_QUEUED, mark_inode_dirty_sync() is the
right thing to do because mark_inode_dirty_sync() now knows not to move
the inode to a writeback list if it is currently queued for sync.
Fixes: 0ae45f63d4 ("vfs: add support for a lazytime mount option")
Cc: stable@vger.kernel.org
Depends-on: 5afced3bf2 ("writeback: Avoid skipping inode writeback")
Link: https://lore.kernel.org/r/20210112190253.64307-2-ebiggers@kernel.org
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5fcd57505c upstream.
The only use of I_DIRTY_TIME_EXPIRE is to detect in
__writeback_single_inode() that inode got there because flush worker
decided it's time to writeback the dirty inode time stamps (either
because we are syncing or because of age). However we can detect this
directly in __writeback_single_inode() and there's no need for the
strange propagation with I_DIRTY_TIME_EXPIRE flag.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5c02406428 upstream.
Otherwise a malicious user could (ab)use the "recalculate" feature
that makes dm-integrity calculate the checksums in the background
while the device is already usable. When the system restarts before all
checksums have been calculated, the calculation continues where it was
interrupted even if the recalculate feature is not requested the next
time the dm device is set up.
Disable recalculating if we use internal_hash or journal_hash with a
key (e.g. HMAC) and we don't have the "legacy_recalculate" flag.
This may break activation of a volume, created by an older kernel,
that is not yet fully recalculated -- if this happens, the user should
add the "legacy_recalculate" flag to constructor parameters.
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Daniel Glockner <dg@emlix.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.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 179e8e47c0 upstream.
The recent commit to fix a memory leak introduced an inadvertant NULL
pointer dereference. The `wacom_wac->pen_fifo` variable was never
intialized, resuling in a crash whenever functions tried to use it.
Since the FIFO is only used by AES pens (to buffer events from pen
proximity until the hardware reports the pen serial number) this would
have been easily overlooked without testing an AES device.
This patch converts `wacom_wac->pen_fifo` over to a pointer (since the
call to `devres_alloc` allocates memory for us) and ensures that we assign
it to point to the allocated and initalized `pen_fifo` before the function
returns.
Link: https://github.com/linuxwacom/input-wacom/issues/230
Fixes: 37309f47e2 ("HID: wacom: Fix memory leakage caused by kfifo_alloc")
CC: stable@vger.kernel.org # v4.19+
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Tested-by: Ping Cheng <ping.cheng@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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>
commit 757fed1d08 upstream.
This reverts commit dde3c6b72a.
syzbot report a double-free bug. The following case can cause this bug.
- mm/slab_common.c: create_cache(): if the __kmem_cache_create() fails,
it does:
out_free_cache:
kmem_cache_free(kmem_cache, s);
- but __kmem_cache_create() - at least for slub() - will have done
sysfs_slab_add(s)
-> sysfs_create_group() .. fails ..
-> kobject_del(&s->kobj); .. which frees s ...
We can't remove the kmem_cache_free() in create_cache(), because other
error cases of __kmem_cache_create() do not free this.
So, revert the commit dde3c6b72a ("mm/slub: fix a memory leak in
sysfs_slab_add()") to fix this.
Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com
Fixes: dde3c6b72a ("mm/slub: fix a memory leak in sysfs_slab_add()")
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
