| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: target: Disable interrupts while holding delayed_cmd_lock
target_do_delayed_work() takes dev->delayed_cmd_lock with a plain
spin_lock(). It runs from system_percpu_wq, so interrupts stay enabled
while the lock is held. Every other acquisition of that lock uses
spin_lock_irqsave(): target_handle_task_attr() and
transport_complete_ordered_sync() in target_core_transport.c, and
target_non_ordered_release() in target_core_device.c.
That was safe while every caller of transport_complete_task_attr() ran
in process context: target_complete_ok_work() from target_completion_wq,
transport_complete_qf() from dev->qf_work_queue, and
transport_generic_request_failure() from the submit and execute paths.
Since commit 06933066d88a ("scsi: target: Add support for completing
commands from backend context") that is no longer true. With
complete_type=1 on a fabric that sets direct_compl_supp,
target_complete() runs target_complete_ok_work() inline in the backend's
completion context, which target_complete_cmd_with_sense() documents as
"May be called from interrupt context". For iblock that is the bio
end_io.
target_complete_ok_work() starts with transport_complete_task_attr(),
which takes delayed_cmd_lock in two ways:
- Every ORDERED command is put on dev->delayed_cmd_list by
target_handle_task_attr() and dispatched from there by
target_do_delayed_work(), which marks it SCF_TASK_ORDERED_SYNC. Its
completion therefore goes through transport_complete_ordered_sync().
- A SIMPLE command that completes while an ORDERED command is pending
drops the last reference to the killed dev->non_ordered, and
percpu_ref_put() then runs target_non_ordered_release() in the
completing context.
Both take the lock and, if commands are waiting, call
schedule_work(&dev->delayed_cmd_work), which queues on system_percpu_wq,
i.e. on the CPU that took the completion. Further completions for the
same queue are typically delivered there too, so one arriving while the
work holds the lock spins on it forever.
Reaching this needs complete_type=1, which is not the default
(vhost-scsi, the only fabric with direct_compl_supp, defaults to
TARGET_QUEUE_COMPL), a backend whose I/O completes from interrupt
context, and ORDERED commands from the initiator. Linux virtio_scsi
guests send only VIRTIO_SCSI_S_SIMPLE and never take the ordered path;
any guest that uses the ORDERED task attribute, which vhost-scsi
accepts, does.
target_do_delayed_work() is a work item and always runs in process
context, so spin_lock_irq() is sufficient.
Found by inspection; no runtime report. A single ORDERED command goes
through both acquisitions, so with CONFIG_PROVE_LOCKING the first one
completed through direct completion should produce an inconsistent lock
state report on delayed_cmd_lock (hardirq or softirq, depending on where
the backend completes). |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: don't hold ci->m_lock while waiting for a lease break ack
When a cifs.ko client caches a read-handle (RH) lease via deferred close
and a conflicting open arrives, ksmbd breaks the lease and waits for the
acknowledgment in wait_for_break_ack() for up to OPLOCK_WAIT_TIME (35s).
__smb_break_all_levII_oplock() runs that wait while holding ci->m_lock
for read.
cifs.ko reacts to a handle-lease break by closing the deferred handle
rather than sending a lease break acknowledgment. That close path
(close_id_del_oplock() -> opinfo_del()) takes ci->m_lock for write and
is exactly what would wake the waiter, but it blocks on the read lock
held by the waiting thread. The break is then resolved only by the 35s
timeout, so xfstests generic/001 takes ~78s with leases enabled versus
~4s with oplocks only.
Collect the target opinfos (each pinned with a reference) while holding
ci->m_lock, then break them after releasing it, matching how
smb_grant_oplock() already breaks a conflicting lease using only a
reference. The reference keeps the opinfo (and its conn and lease)
alive across the unlocked window, and a close racing the break is
handled by the existing OPLOCK_CLOSING state check. Apply the same fix
to the parent lease break paths. |
| Deadlock in Windows Routing and Remote Access Service (RRAS) allows an unauthorized attacker to deny service over a network. |
| In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Don't run ops.dequeue() with a DSQ lock held
ops.dequeue() is invoked with the source user DSQ's lock still held on
the consume and move paths (scx_consume_dispatch_q(),
move_task_between_dsqs()). A BPF scheduler which locks the source user
DSQ from ops.dequeue() - e.g. by iterating it with bpf_iter_scx_dsq -
self-deadlocks.
ops.dequeue() can only call the "any" kfuncs and none of them can lock a
builtin DSQ, so the global and bypass paths can't deadlock; however,
all DSQ locks share one lockdep class, so iterating any user DSQ from
ops.dequeue() on those paths trips the recursion check.
Move the invocation after the DSQ unlock on all three paths.
SCX_TASK_IN_CUSTODY is cleared under the lock serializing the transfer
so that the callback is invoked exactly once. |
| In the Linux kernel, the following vulnerability has been resolved:
mm/slab: do not wake up kswapd in __kfree_rcu_sheaf()
Since kfree_rcu() can be called under pi_lock (a raw spinlock in the
scheduler), kfree_rcu() itself should never allocate memory with
__GFP_KSWAPD_RECLAIM as waking up kswapd ends up acquiring pi_lock,
which leads to a deadlock.
Reproducing the issue even intentionally was not straightforward.
The set_cpus_allowed_force() path that is called under pi_lock is
exercised very rarely, and competing tasks that allocate memory will
most likely wake kswapd up.
Therefore the existence of the deadlock was verified with a modified
kernel that has a lockdep map for waking up kswapd:
======================================================
WARNING: possible circular locking dependency detected
7.2.0-rc1-slab-for-next+ #10 Not tainted
------------------------------------------------------
git/6660 is trying to acquire lock:
ffff8e524533c550 (&p->pi_lock){-.-.}-{2:2}, at: _raw_spin_lock_irqsave+0x12/0x20
but task is already holding lock:
ffff8e57bffff1a0 (&pgdat->kswapd_wait){....}-{3:3}, at: _raw_spin_lock_irqsave+0x12/0x20
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&pgdat->kswapd_wait){....}-{3:3}:
__lock_acquire+0x5a4/0xc50
lock_acquire.part.0+0xb7/0x240
lock_acquire+0x70/0x170
__raw_spin_lock_irqsave+0x44/0x80
_raw_spin_lock_irqsave+0x12/0x20
__wake_up_common_lock+0x31/0xa0
__wake_up+0x20/0x40
kswapd_wakeup_wake+0x7e/0x110
wakeup_kswapd+0x295/0x320
wake_all_kswapds+0xac/0x1a0
__alloc_pages_slowpath.constprop.0+0x282/0xf80
__alloc_frozen_pages_noprof+0x32a/0x360
alloc_slab_page+0x2e/0x160
allocate_slab+0x82/0x420
new_slab+0x52/0xb0
refill_objects+0x13d/0x190
refill_sheaf+0x5d/0xd0
__pcs_replace_empty_main+0x230/0xb10
[...]
-> #1 (kswapd_wakeup){-.-.}-{0:0}:
__lock_acquire+0x5a4/0xc50
lock_sync.part.0+0x75/0x100
lock_sync+0x36/0x70
might_wakeup_kswapd+0x61/0xa0
__kfree_rcu_sheaf+0x33/0xd90
kvfree_call_rcu+0x1d4/0x3b0
set_cpus_allowed_force+0x163/0x220
cpuset_cpus_allowed_fallback+0x18b/0x240
select_fallback_rq+0x1e6/0x250
[...]
-> #0 (&p->pi_lock){-.-.}-{2:2}:
check_prev_add+0xe6/0xe00
validate_chain+0x51e/0x6e0
__lock_acquire+0x5a4/0xc50
lock_acquire.part.0+0xb7/0x240
lock_acquire+0x70/0x170
__raw_spin_lock_irqsave+0x44/0x80
_raw_spin_lock_irqsave+0x12/0x20
try_to_wake_up+0x77/0xa90
default_wake_function+0x27/0x60
autoremove_wake_function+0x23/0xb0
__wake_up_common+0xb8/0x170
__wake_up_common_lock+0x51/0xa0
__wake_up+0x20/0x40
kswapd_wakeup_wake+0x7e/0x110
wakeup_kswapd+0x295/0x320
wake_all_kswapds+0xac/0x1a0
__alloc_pages_slowpath.constprop.0+0x282/0xf80
__alloc_frozen_pages_noprof+0x32a/0x360
alloc_slab_page+0x2e/0x160
allocate_slab+0x82/0x420
new_slab+0x52/0xb0
refill_objects+0x13d/0x190
refill_sheaf+0x5d/0xd0
__pcs_replace_empty_main+0x230/0xb10
[...]
other info that might help us debug this:
Chain exists of:
&p->pi_lock --> kswapd_wakeup --> &pgdat->kswapd_wait
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&pgdat->kswapd_wait);
lock(kswapd_wakeup);
lock(&pgdat->kswapd_wait);
lock(&p->pi_lock);
*** DEADLOCK ***
3 locks held by git/6660:
#0: ffff8e519f0e9e20 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: lookup_slow+0x2d/0x60
#1: ffffffff8a31c460 (kswapd_wakeup){-.-.}-
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: connect the session socket without rfcomm_mutex
An RFCOMM connect() issued while a BR/EDR link is being authenticated
makes lockdep report a circular dependency, and the reported cycle is a
real AB/BA between rfcomm_mutex and hdev->lock.
rfcomm_security_cfm() is called from the HCI event path, which already
holds hdev->lock:
hci_rx_work()
hci_event_packet()
hci_cc_read_enc_key_size() [hdev->lock]
hci_encrypt_cfm() [hci_cb_list_lock]
rfcomm_security_cfm() [rfcomm_mutex]
while an RFCOMM connect() from userspace takes the same two locks the
other way round:
rfcomm_sock_connect()
rfcomm_dlc_open() [rfcomm_mutex]
__rfcomm_dlc_open()
rfcomm_session_create()
kernel_connect()
l2cap_sock_connect()
l2cap_chan_connect() [hdev->lock]
WARNING: possible circular locking dependency detected
kworker/u131:1/1128 is trying to acquire lock:
rfcomm_mutex, at: rfcomm_security_cfm+0x31/0x3e0 [rfcomm]
but task is already holding lock:
hci_cb_list_lock, at: hci_cc_read_enc_key_size+0x1d2/0xcc0
Chain exists of:
rfcomm_mutex --> &hdev->lock --> hci_cb_list_lock
hci_auth_complete_evt() and hci_encrypt_change_evt() reach the callback
the same way.
Both orders have to be seen in the same boot, which is why a BR/EDR
connection alone is not enough to show it: a session set up by the
remote side is created by rfcomm_accept_connection() in krfcommd, which
calls kernel_accept() and never takes hdev->lock under rfcomm_mutex.
Connecting a device that authenticates and encrypts the link and then
calling connect() on an RFCOMM socket towards any address - the connect
does not have to succeed, the order is recorded before the page timeout
- reports it every time.
Only the session socket has to be connected with the lock held, and it
does not: nothing else can see the socket before it is put on the
session list. So connect it first and take rfcomm_mutex afterwards,
which removes the rfcomm_mutex -> hdev->lock order for good, rather
than keeping the HCI event path out of rfcomm_mutex.
rfcomm_session_create() becomes rfcomm_session_connect(), which returns
the connected socket without touching the session list, and
rfcomm_dlc_open() adds the session once it holds the lock again. If
another opener added a session for the same pair while this socket was
connecting, that session is used and this socket is dropped.
__rfcomm_dlc_open() now takes the session it should use, and its state
check runs after the lock is re-acquired, so a DLC that was opened or
closed in the meantime is still handled.
Over an existing ACL link the connection can complete before the
session reaches the list, and the wakeup from the socket callback is
then lost, so krfcommd is woken once the session is visible.
Connecting without the lock opens a window in which the socket can be
closed. The DLC is not on a session yet, so rfcomm_dlc_close() finds
nothing to do and returns without touching it, and rfcomm_dlc_open()
would then attach a DLC whose owner is gone. rfcomm_dlc_close() now
marks such a DLC with RFCOMM_CLOSED, and rfcomm_dlc_open() checks the
mark once it holds rfcomm_mutex again and drops the socket instead of
attaching the DLC. The mark is cleared when an open starts, so a DLC
that is reused is not affected. This covers both callers of
rfcomm_dlc_open(), the socket and the tty layer. |
| In the Linux kernel, the following vulnerability has been resolved:
blk-cgroup: save IRQ state in blkg_tryget_closest()
bio_set_dev() associates the bio with a blkg through bio_associate_blkg().
If the blkg lookup misses, blkg_tryget_closest() takes q->queue_lock with
spin_lock_irq() and releases it with spin_unlock_irq(), which
unconditionally enables local interrupts.
Callers may call bio_set_dev() with interrupts already disabled, e.g.
dm-thin's pool_map() does so while holding pool->lock taken with
spin_lock_irq(). The nested spin_unlock_irq() then enables interrupts
while pool->lock is still held, so an I/O completion softirq can run on
the same CPU, re-acquire pool->lock (thin_endio(), or overwrite_endio()
-> complete_mapping_preparation()) and deadlock. lockdep reports this
as inconsistent SOFTIRQ-ON-W to IN-SOFTIRQ-W usage.
Commit 3a762de55b4e ("block: save irq state in blkg_lookup_create()")
fixed the same problem while the lock lived in blkg_lookup_create(), but
commit 9327a865e395 ("blk-cgroup: don't nest queue_lock under rcu in
blkg_lookup_create()") moved the locking into blkg_tryget_closest() and
reverted it to spin_lock_irq().
Save and restore the caller's IRQ state instead. |
| In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix CPU hotplug hang when a dying CPU's tasks sit in the BPF scheduler
A CPU going down has to empty its own rq. Its hotplug thread waits in
sched_cpu_wait_empty() until nothing else is left, and the only thing that
wakes it is balance_push(), which runs from __schedule() on the dying CPU
and pushes off the migratable tasks the CPU picks.
sched_ext breaks this. A task sitting on a user DSQ or held by the BPF
scheduler is still counted on its rq, but an inactive CPU no longer calls
ops.dispatch() and can't pull the task back. The dying CPU goes idle with
the task still counted, and one of two things happens:
- Another CPU consumes the task. The rq empties without a __schedule() on
the dying CPU, so the hotplug thread is never woken and cpu_down() hangs
holding cpu_hotplug_lock.
- The task is affine only to the dying CPU. Nothing can move it, and the
offline stalls until the watchdog ejects the BPF scheduler.
When the rq goes offline, re-enqueue every task on it that isn't already on
the local DSQ. An enqueue on an offline rq lands on the local DSQ, so the
dying CPU itself picks the tasks and balance_push() pushes them off, the
same as for the other sched classes. From then on no sched_ext path on
another CPU can pull a task off the rq.
ops.dispatch() currently stops as soon as the CPU goes inactive, and CPU
hotplug then waits for an RCU grace period before taking the rq offline. A
BPF-held task affine only to the dying CPU and preempted inside an RCU
read-side critical section would block that grace period, and the rq would
never go offline. Test SCX_RQ_ONLINE directly so that ops.dispatch() keeps
running until the rq goes offline. Only the dying CPU's own hotplug thread
clears the flag during teardown, and task_can_run_on_remote_rq() still keeps
other rqs' tasks off the CPU. |
| Improper synchronization in the OpenVPN ovpn-dco-win for Windows versions 0.6.5 through 1.3.5 and 2.4.0 through 2.8.7 allows local attackers to trigger a deadlock via a crafted write to the ovpn-dco device, causing the host to become unresponsive. |
| In the Linux kernel, the following vulnerability has been resolved:
cxgb4/ch_ktls: disable softirqs around tid_list erases
chcr_ktls_cpl_act_open_rpl() inserts into tid_list from the receive path
using xa_insert_bh(). The array is shared by the adapter's connections
and initialized with XA_FLAGS_LOCK_BH. However, chcr_ktls_dev_del() and
the chcr_ktls_dev_add() error path use xa_erase(), which takes the XArray
lock without disabling softirqs.
When cleanup runs with softirqs enabled, a receive softirq for another
connection on the same CPU can interrupt the erase and spin on the lock
held by the interrupted task. Use xa_erase_bh() at both sites to match
the insertion path. |
| In the Linux kernel, the following vulnerability has been resolved:
x86/mm: Drop unnecessary PMD page copy when freeing
On a box with a discrete GPU, lockdep reports a possible deadlock as
soon as kswapd shrinks the TTM page pool. The immediate cause is an
x86 commit that added an mmap_read_lock() to kernel page protection
munging code.
The huge vmap code holds the same lock over a GFP_KERNEL allocation,
which is a no-no now that reclaim can take it. That allocation is in a
page table *free* path and ends up being for dubious purposes[1].
Basically, it tries to avoid hardware setting Accessed=1 in page table
entries that are unreachable by the hardware, a non-issue.
Remove the PMD copy. Detach the original PMD page at the PUD, flush
the mid-level caches, and free the PTE tables straight from the
detached PMD page. With no allocation left, the locking issue is gone.
Lockdep splat/analysis:
WARNING: possible circular locking dependency detected
7.3.0-rc3-f6e7b42bf05b+ #183 Tainted: G U
------------------------------------------------------
kswapd0/269 is trying to acquire lock:
((init_mm).mmap_lock){++++}-{4:4}, at: change_page_attr_set_clr+0x29a/0x4a0
but task is already holding lock:
(pool_shrink_rwsem){.+.+}-{4:4}, at: ttm_pool_shrink+0xb2/0x330 [ttm]
Chain exists of:
(init_mm).mmap_lock --> fs_reclaim --> pool_shrink_rwsem
The cycle is built from three edges:
1) pool_shrink_rwsem -> (init_mm).mmap_lock
The TTM shrinker restores the caching attribute of every page it
frees, while holding pool_shrink_rwsem:
ttm_pool_shrink()
-> ttm_pool_dispose_list()
-> ttm_pool_free_page()
-> set_pages_wb()
-> change_page_attr_set_clr() [ init_mm mmap read lock ]
2) fs_reclaim -> pool_shrink_rwsem
The same shrinker, called from reclaim.
3) (init_mm).mmap_lock -> fs_reclaim
ioremap() installing a huge PUD mapping over an existing PMD table:
ioremap_page_range()
-> vmap_range_noflush()
-> vmap_try_huge_pud() [ init_mm mmap read lock ]
-> pud_free_pmd_page()
-> __get_free_page(GFP_KERNEL) [ enters reclaim ]
[ dhansen: Lots of changelog munging/trimming and merged comments from my
version of the fix. ] |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: ufs: core: Keep internal commands dispatchable during error handling
Commit 08b12cda6c44 ("scsi: ufs: core: Switch to scsi_get_internal_cmd()")
switched UFS internal commands to allocate requests on
hba->host->pseudo_sdev->request_queue, which shares the host tagset with
regular LUNs.
During error recovery, ufshcd_err_handling_prepare() calls
blk_mq_quiesce_tagset(&hba->host->tag_set), marking all queues in the
tagset as quiesced, including pseudo_sdev->request_queue. When
ufshcd_verify_dev_init() subsequently issues internal commands (e.g. NOP
OUT UPIU) via blk_execute_rq(), blk_mq_run_hw_queue() skips running the
quiesced queue, resulting in an unrecoverable circular wait deadlock.
Keep quiescing the tagset and unquiesce the pseudo SCSI device on top of
that, so internal commands stay dispatchable while the logical units remain
quiesced. Re-quiesce the pseudo device before unquiescing the tagset so
that quiesce_depth stays balanced.
Clock scaling and ufshcd_pause_command_processing() are unaffected: they
keep quiescing the whole tagset, internal commands included. |
| In the Linux kernel, the following vulnerability has been resolved:
md/raid1,raid10: fix error-path detection with md_cloned_bio()
Detect the error path using md_cloned_bio() instead of relying
on r1_bio in raid1 or r10_bio->read_slot in raid10, which may be
NULL or -1 after splitting and resubmitting a failed bio.
As a result, the error path may not be recognized and memory
allocations can incorrectly use GFP_NOIO instead of
(GFP_NOIO | __GFP_HIGH), which can lead to a deadlock under
memory pressure. |
| In the Linux kernel, the following vulnerability has been resolved:
md/raid5: avoid R5_Overlap races while breaking stripe batches
KCSAN report a race in break_stripe_batch_list() vs. raid5_make_request()
on sh->dev[i].flags (plain word write vs. atomic bit op)..
and .. one possible scenario is:
CPU1 CPU2
break_stripe_batch_list(sh1)
-> handle sh2
-> lock(sh2)
-> sh2->batch_head = NULL
-> unlock(sh2)
-> test_and_clear_bit(R5_Overlap, sh2->dev[i].flags)
-> wake_up_bit(sh2->dev[i].flags)
raid5_make_request()
-> add_all_stripe_bios(sh2)
-> lock(sh2)
-> stripe_bio_overlaps(sh2) returns true
batch_head is NULL, so new bio overlap
exist bio on sh2 -> true
-> set_bit(R5_Overlap, sh2->dev[i].flags)
-> unlock(sh2)
-> wait_on_bit(sh2->dev[i].flags)
-> sh2->dev[i].flags = sh1->dev[i].flags & ~R5_Overlap
No wait_up_bit(), CPU2 could be wait_on_bit() forever...
Fix by :
- Expand the protect zone.
- Use batch_head's device flag's snaphot when no held head_sh->stripe_lock.
- Move sh/head_sh->batch_head = NULL to the end of protected zone , and ,
any concurrent add_all_stripe_bios() grabs sh->stripe_lock now either:
- see batch_head != null, and , is rejected by stripe_bio_overlaps()
under the lock (no R5_Overlap wait ) , or ,
- sees batch_head == NULL, only after dev[i].flags has already been
set and the prior R5_Overlap waiters worken.
KCSAN report:
================================================
BUG: KCSAN: data-race in break_stripe_batch_list / raid5_make_request
write (marked) to 0xffff8e89c8117548 of 8 bytes by task 4042 on cpu 0:
raid5_make_request+0xea0/0x2930
md_handle_request+0x4a2/0xa40
md_submit_bio+0x109/0x1a0
__submit_bio+0x2ec/0x390
submit_bio_noacct_nocheck+0x457/0x710
submit_bio_noacct+0x2a7/0xc20
submit_bio+0x56/0x250
blkdev_direct_IO+0x54c/0xda0
blkdev_write_iter+0x38f/0x570
aio_write+0x22b/0x490
io_submit_one+0xa51/0xf70
__x64_sys_io_submit+0xf7/0x220
x64_sys_call+0x1907/0x1c60
do_syscall_64+0x130/0x570
entry_SYSCALL_64_after_hwframe+0x76/0x7e
read to 0xffff8e89c8117548 of 8 bytes by task 4010 on cpu 5:
break_stripe_batch_list+0x249/0x480
handle_stripe_clean_event+0x720/0x9b0
handle_stripe+0x32fb/0x4500
handle_active_stripes.isra.0+0x6e0/0xa50
raid5d+0x7e0/0xba0
md_thread+0x15a/0x2d0
kthread+0x1e3/0x220
ret_from_fork+0x37a/0x410
ret_from_fork_asm+0x1a/0x30
value changed: 0x0000000000000019 -> 0x0000000000000099 --> R5_Overlap |
| In the Linux kernel, the following vulnerability has been resolved:
RDMA/erdma: Use IRQ-safe XArray helpers for QP and CQ tables
Locked QP and CQ lookups from EQ interrupts can deadlock with
create-path XArray updates. If an interrupt arrives while the create
path holds the plain xa_lock, the lookup spins forever trying to
acquire the same lock.
Use IRQ-safe XArray helpers for all QP and CQ create-path updates,
including the GSI QP store and error paths. Initialize both arrays with
XA_FLAGS_LOCK_IRQ so sleeping allocations preserve interrupt state. |
| In the Linux kernel, the following vulnerability has been resolved:
io_uring/rw: end write accounting from ->ki_complete
Commit b000145e9907 moved both the fsnotify calls and the write
accounting out of the kiocb completion handler and into the
io_req_rw_complete() task_work. However, only the fsnotify part actually
needed to move as it may sleep. Ending the write accounting is just a
percpu_up_read() on the superblock writers sem.
Deferring it is a problem, because it makes dropping SB_FREEZE_WRITE
protection depend on the ring owner getting to running task_work. But
the task may be blocked in freeze_super(), causing it to never get to
that:
task io-wq worker
--------------------------------------------------------------
io_write()
io_kiocb_start_write() (takes sb_writers, hidden from
lockdep by __sb_writers_release)
write_iter() -> -EIOCBQUEUED
ioctl(FS_IOC_SHUTDOWN)
bdev_freeze()
freeze_super()
percpu_down_write() <- waits for the reader above
io_write()
kiocb_start_write()
percpu_down_read() <- queued
behind the
writer
<bio completes>
io_complete_rw()
queues io_req_rw_complete() <- never runs, task is in D state
End the write from io_complete_rw() instead, and leave only the fsnotify
calls in task_work. |
| In the Linux kernel, the following vulnerability has been resolved:
md/raid1,raid10: fix deadlock in read error recovery path
raid1d and raid10d may resubmit a split md cloned bio while handling
a read error. In this case, resubmitting the bio can lead to a deadlock
if the array is suspended before md_handle_request() acquires an
active_io reference via percpu_ref_tryget_live().
Since the cloned bio already holds an active_io reference,
trying to acquire another reference via percpu_ref_tryget_live()
can lead to a deadlock while the array is suspended.
Fix this by using percpu_ref_get() for md cloned bios. |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix deadlock cloning inline extent when using flushoncommit
In commit b48c980b6a7e ("btrfs: fix deadlock between reflink and
transaction commit when using flushoncommit") a deadlock was fixed
between reflinks and transaction commits when the fs is mounted with the
flushoncommit option. This happened when we had to copy an inline extent's
data to the destination file. However the issue was fixed only for the
case where the destination offset is 0, it missed the case when the offset
is greater than zero.
Fix this by ensuring we get i_size update whenever we copied an inline
extent's data into the destination file.
Syzbot reported this with the following trace:
INFO: task kworker/u8:3:57 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:3 state:D stack:21600 pid:57 tgid:57 ppid:2 task_flags:0x4208160 flags:0x00080000
Workqueue: writeback wb_workfn (flush-btrfs-129)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5402 [inline]
__schedule+0x16f9/0x5500 kernel/sched/core.c:7204
__schedule_loop kernel/sched/core.c:7283 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7298
wait_extent_bit fs/btrfs/extent-io-tree.c:905 [inline]
btrfs_lock_extent_bits+0x59c/0x700 fs/btrfs/extent-io-tree.c:2008
btrfs_lock_extent fs/btrfs/extent-io-tree.h:152 [inline]
btrfs_invalidate_folio+0x440/0xc00 fs/btrfs/inode.c:7718
extent_writepage fs/btrfs/extent_io.c:1848 [inline]
extent_write_cache_pages fs/btrfs/extent_io.c:2552 [inline]
btrfs_writepages+0x12f3/0x2410 fs/btrfs/extent_io.c:2684
do_writepages+0x32e/0x550 mm/page-writeback.c:2571
__writeback_single_inode+0x133/0x10e0 fs/fs-writeback.c:1764
writeback_sb_inodes+0x97f/0x1980 fs/fs-writeback.c:2056
wb_writeback+0x445/0xb00 fs/fs-writeback.c:2241
wb_do_writeback fs/fs-writeback.c:2388 [inline]
wb_workfn+0x3fd/0xf20 fs/fs-writeback.c:2428
process_one_work+0x98b/0x1630 kernel/workqueue.c:3318
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: task syz.0.145:8523 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.145 state:D stack:22752 pid:8523 tgid:8522 ppid:5850 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5402 [inline]
__schedule+0x16f9/0x5500 kernel/sched/core.c:7204
__schedule_loop kernel/sched/core.c:7283 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7298
wb_wait_for_completion+0x3e8/0x790 fs/fs-writeback.c:227
__writeback_inodes_sb_nr+0x24c/0x2d0 fs/fs-writeback.c:2847
try_to_writeback_inodes_sb+0x9a/0xc0 fs/fs-writeback.c:2895
btrfs_start_delalloc_flush fs/btrfs/transaction.c:2182 [inline]
btrfs_commit_transaction+0x813/0x2fc0 fs/btrfs/transaction.c:2371
btrfs_sync_file+0xdf4/0x1230 fs/btrfs/file.c:1822
generic_write_sync include/linux/fs.h:2663 [inline]
btrfs_do_write_iter+0x6a9/0x840 fs/btrfs/file.c:1473
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x629/0xba0 fs/read_write.c:688
ksys_write+0x156/0x270 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5a0bdece59
RSP: 002b:00007f5a0b446028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5a0c065fa0 RCX: 00007f5a0bdece59
RDX: 000000000000029f RSI: 0000200000
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT
Reject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not
belong to the same superblock as the original file. Currently, this
validation is performed inside ext4_move_extents() by
mext_check_validity(), but only after lock_two_nondirectories() has
already acquired the inode locks. When the donor fd refers to a file
on a different filesystem (e.g., overlayfs), this late validation
creates a circular lock dependency:
CPU0 (overlayfs write) CPU1 (ext4 ioctl)
---- ----
inode_lock(ovl_inode)
mnt_want_write_file(filp)
sb_start_write(ext4_sb) [sb_writers]
backing_file_write_iter()
vfs_iter_write(real_file)
file_start_write(real_file)
sb_start_write(ext4_sb) [blocked by freeze]
lock_two_nondirectories()
inode_lock(ovl_inode) [blocked]
With a concurrent freeze operation holding sb_writers write side, this
forms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits
for CPU1's sb_writers reader to exit, CPU1 waits for CPU0's inode lock.
Since EXT4_IOC_MOVE_EXT exchanges physical extents between two files,
it fundamentally requires both files to reside on the same ext4
filesystem. Moving the superblock check before any lock acquisition
is both semantically correct and eliminates the circular dependency
by ensuring that cross-filesystem donor fds are rejected before
sb_writers or inode locks are taken. |
| In the Linux kernel, the following vulnerability has been resolved:
ntfs: skip extent mft records in writeback to prevent deadlock
This patch fixes the ABBA deadlock between extent_lock and extent
mrec_lock triggered by xfstests generic/113, that occurs since the commit
6994acf33bae ("ntfs: use base mft_no when looking up base inode for
extent record").
Path A (inode writeback):
VFS writeback
-> ntfs_write_inode()
-> __ntfs_write_inode()
-> mutex_lock(&ni->extent_lock)
-> mutex_lock(&tni->mrec_lock)
Path B (MFT folio writeback):
VFS writeback of $MFT dirty folios
-> ntfs_mft_writepages()
-> ntfs_write_mft_block()
-> ntfs_may_write_mft_record()
-> holds one extent mrec_lock from a previous iteration
-> tries to acquire another base inode extent_lock
By removing all extent_lock and extent mrec_lock acquisition from the MFT
folio writeback path, the ABBA lock ordering is eliminated:
Path A: __ntfs_write_inode(): extent_lock -> mrec_lock
Path B (removed): ntfs_write_mft_block(): mrec_lock -> extent_lock
Path B is always redundant for extent records because:
1. mark_mft_record_dirty(ext_ni) does NOT dirty the MFT folio.
It only sets NInoDirty(ext_ni) and marks the base VFS inode dirty
via __mark_inode_dirty(I_DIRTY_DATASYNC), which triggers Path A.
Therefore, normal extent modifications never create a situation where
the MFT folio is dirty and Path B is not scheduled.
2. The MFT folio only gets dirtied via ntfs_mft_mark_dirty() inside
ntfs_mft_record_alloc(). But all identified callers in attrib.c
(ntfs_attr_add, ntfs_attr_record_move_away,
ntfs_attr_make_non_resident, ntfs_attr_record_resize) follow through
with mark_mft_record_dirty(), which triggers Path A to write the
complete record.
3. ntfs_evict_big_inode() calls ntfs_commit_inode() before freeing extent
inodes, ensuring all dirty extents are flushed via Path A before the
base inode leaves the icache. |
