mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()
In the Linux kernel, the following vulnerability has been resolved:
mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()
migrate_pages_batch() unmaps each folio before moving it, and every
unmap runs the mmu_notifier invalidate callbacks. On KVM hosts
try_to_migrate() ends up in kvm_mmu_notifier_invalidate_range_start() ->
tdp_mmu_zap_leafs(), which is expensive, so unmapping a large batch keeps
the CPU busy for a long time.
The loop already calls cond_resched(), but on PREEMPTION kernels that is
a no-op, and involuntary preemption is not a Tasks-RCU quiescent state.
A long batch therefore never reports a quiescent stat
mm/migrate_device: clear stale mapping after freeing swapcache
In the Linux kernel, the following vulnerability has been resolved:
mm/migrate_device: clear stale mapping after freeing swapcache
__migrate_device_pages() reads the folio mapping before calling
folio_free_swap(). When folio_free_swap() succeeds, the folio is removed
from the swap cache, but the saved mapping still points to swap_space.
Passing the stale mapping to folio_migrate_mapping() makes it use the
mapped-folio path for a folio that is no longer in swapcache. It can then
operate on swap_space.i_pages with invalid reference accounting,
eventually triggering a folio reference count BUG.
After a successful split, nr still contains t
mm/pagewalk: fix stale walk->action escaping walk_pmd_range()
In the Linux kernel, the following vulnerability has been resolved:
mm/pagewalk: fix stale walk->action escaping walk_pmd_range()
If ->pmd_entry() sets walk->action = ACTION_AGAIN, the pmd_none() check is
retried. The PMD entry may be cleared at the point of retry.
In this case, if walk->ops->install_pte is not specified, the code
continues to the next PMD entry in the range without resetting
walk->action to ACTION_SUBTREE.
This leaves walk->action erroneously set to ACTION_AGAIN, which is
incorrect.
This was incorrect but not problematic up until commit 3b89863c3fa4
("mm/pagewalk: fix race between concurrent split and refault") which
u
mm/vmscan: report RCU-tasks quiescent states in shrink_lruvec()
In the Linux kernel, the following vulnerability has been resolved:
mm/vmscan: report RCU-tasks quiescent states in shrink_lruvec()
I am seeing some rcu_tasks stalls in the Meta fleet during reclaim.
INFO: rcu_tasks detected stalls on tasks:
0000000088620d09: .. nvcsw: 6735/6735 holdout: 1 idle_cpu: -1/8
task:GlobalCPUThread state:R running task pid:2552016 tgid:2524552
Call Trace:
shrink_lruvec
mem_cgroup_iter
shrink_node
do_try_to_free_pages
try_to_free_pages
__alloc_frozen_pages_noprof
alloc_pages_noprof
pte_alloc_one
__pte_alloc
handle_mm_fault
Nothing promises direct reclaim returns in bounded ti
mm: memcg: stop reclaim when a limit update is superseded
In the Linux kernel, the following vulnerability has been resolved:
mm: memcg: stop reclaim when a limit update is superseded
kernfs serializes file operations only per open file, so separate open
files can update the same memory.high or memory.max file concurrently.
Both handlers store the new limit before synchronous reclaim, but continue
to use the writer's local target in the reclaim loop. If another writer
raises or removes the limit, the first writer can continue reclaiming
toward a stale target.
For memory.max, this can leave the writer looping indefinitely once
reclaim retries are exhausted. The OOM path sees sufficient margin u
In the Linux kernel, the following vulnerability has been resolved:
x86/tdx: Fix off-by-one in port I/O handling
handle_in() and handle_out() in arch/x86/coco/tdx/tdx.c use:
u64 mask = GENMASK(BITS_PER_BYTE * size, 0);
GENMASK(h, l) includes bit h. For size=1 (INB), this produces
GENMASK(8, 0) = 0x1FF (9 bits) instead of GENMASK(7, 0) = 0xFF (8
bits). The mask is one bit too wide for all I/O sizes.
Fix the mask calculation.
tracing/user_events: Clear copied tracing state before fork duplication
In the Linux kernel, the following vulnerability has been resolved:
tracing/user_events: Clear copied tracing state before fork duplication
dup_task_struct() copies user_event_mm from the parent into the child,
without grabbing a reference to it. user_event_mm_dup() should
replace it, but it leaves that copied pointer unmodified if
user_event_mm_alloc() fails.
When the child exits, user_event_mm_remove() decrements a reference
the child never owned, which ultimately frees user_event_mm, while
the parent still as a stale pointer to it. This creates a UAF, which
KASAN reports as:
BUG: KASAN: slab-use-after-free in
current_user_event
tracing: Fix crash passing ERR_PTR to kthread_stop()
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix crash passing ERR_PTR to kthread_stop()
event_test_stuff() calls kthread_run() and unconditionally passes the
returned task_struct pointer to kthread_stop(). kthread_run() returns an
error pointer such as ERR_PTR(-ENOMEM) when kthread creation fails, for
example under memory pressure during the boot-time event self-test.
kthread_stop() then dereferences the invalid pointer, crashing the kernel.
Check the result of kthread_run() before passing it to kthread_stop(). Use
WARN_ON() so that a failure to create the self-test thread does not go
unnoticed, matching th
tracing: Fix retry exhaustion in simple ring buffer reader swap
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix retry exhaustion in simple ring buffer reader swap
simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
post-decrements it only after a failed link replacement. On the final
attempt, a successful replacement leaves retry at zero, while a failed
replacement leaves it at -1.
The current !retry test reverses both outcomes. It returns an error after
a successful final replacement, leaving the link update complete but the
reader bookkeeping unfinished. After a failed final replacement, it
falls through and updates the head and reader pointers as tho
tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
Writing to buffer_subbuf_size_kb calls ring_buffer_subbuf_order_set(),
which frees every sub-buffer of the ring buffer, including the reader
page, and replaces them with newly allocated ones.
Readers of trace_pipe hold pointers into those pages. ring_buffer_peek()
looks up an event under cpu_buffer->reader_lock but returns the event
pointer after dropping the lock, and peek_next_entry() then calls
ring_buffer_event_length() and ring_buffer_event_data() on it. If the
sub-buffer order is changed in tha
tracing: Fix use-after-free with same-name named triggers
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix use-after-free with same-name named triggers
When two hist triggers on different events are registered with the same
name=, the second one reuses the first as named_data. Both are added to
tr->hist_vars by save_hist_vars() during event_hist_trigger_parse(),
because save_hist_vars() is called before event_trigger_register() while
the named reuse is only detected later, in hist_register_trigger().
In the named-data branch hist_register_trigger() then frees the second
histogram's hist_data via destroy_hist_data(), but never removes its
tr->hist_vars list entry,
In the Linux kernel, the following vulnerability has been resolved:
debugfs: Fix lockdown check for mmap_prepare
Commit 651fdda8406d ("relay: update relay to use mmap_prepare")
changed the `mmap` file operation to `mmap_prepare` for relayfs, but
the lockdown check in debugfs was not updated accordingly.
This prevents debugfs from being locked down when the kernel is in
integrity mode if a file uses `mmap_prepare` but not `mmap`.
Since the conversion to `mmap_prepare` across the kernel is not yet
complete, update the lockdown check to look for both `mmap` and
`mmap_prepare` to ensure comprehensive coverage.
device property: fix infinite loop in fwnode_for_each_child_node()
In the Linux kernel, the following vulnerability has been resolved:
device property: fix infinite loop in fwnode_for_each_child_node()
When iterate over children of a fwnode that has a secondary fwnode,
fwnode_get_next_child_node() can enter an infinite loop if the secondary
fwnode has more than one child.
Parent Child
(Primary fwnode) FWa: {FWa1, FWa2, FWa3}
(Secondary fwnode) FWb: {FWb1, FWb2}
In this case:
┌─> fwnode_get_next_child_node(FWa, FWa1)
│ - fwnode_call_ptr_op(FWa, get_next_child_node, FWa1) returns FWa2
│
│ ...
│
│ fwnode_get_next_child_node(FWa, FWa3)
│ - fwn
misc: nsm: bound the device-reported response length
In the Linux kernel, the following vulnerability has been resolved:
misc: nsm: bound the device-reported response length
nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported
by the NSM device into msg->resp.len without bounding it to the response
buffer. A malicious or buggy backend can report a length larger than the
response buffer; parse_resp_raw() then copies that many bytes out of the
fixed buffer to user space, disclosing adjacent kernel heap (an
out-of-bounds read). The request path already floors its length in
fill_req_raw(); the response path lacks the symmetric check.
Clamp the stored length to the size of the
rapidio: mport_cdev: fix use-after-free in dma_req_free()
In the Linux kernel, the following vulnerability has been resolved:
rapidio: mport_cdev: fix use-after-free in dma_req_free()
dma_req_free() acquires buf_mutex through req->map, drops the mapping
reference with kref_put(), and then dereferences req->map again to unlock
the mutex.
If kref_put() drops the last reference, mport_release_mapping() frees the
mapping, and the subsequent mutex_unlock() dereferences a freed object.
This is a use-after-free.
Fix this by caching map and md before kref_put(), clearing req->map while
holding buf_mutex, and using the cached md for mutex unlocking.
The bug is reachable from userspace via the RapidIO m
Revert "media: v4l2-dev: fix error handling in __video_register_device()"
In the Linux kernel, the following vulnerability has been resolved:
Revert "media: v4l2-dev: fix error handling in __video_register_device()"
This reverts commit 2a934fdb01db6458288fc9386d3d8ceba6dd551a.
The intentions of that patch were good, but it doesn't work.
The idea is that if device_register fails, you have to do a put_device
to let the ref counter release resources.
However, the V4L2 API says that if video_register_device() fails, then
you have to call video_device_release(), which kfree()s the video_device
struct.
But the put_device() will already have freed the struct, so you end
up in a double-free scenario.
There is not re
In the Linux kernel, the following vulnerability has been resolved:
serial: imx: serialize imx_uart_ports[] lifetime
imx_uart_probe() publishes its devm-allocated port in imx_uart_ports[]
before uart_add_one_port() because console setup uses the table. The entry
is not cleared when adding the port fails or after removal, leaving a
dangling pointer.
A sibling probe can register the shared console through that stale entry.
This was reproduced under KASAN on QEMU mcimx6ul-evk by unbinding a
sibling UART, unbinding the console UART and rebinding the sibling.
Keep the entry valid through uart_remove_one_port(), then clear it. Protect
port addi
usb: dwc3: gadget: Fix use-after-free in dwc3_gadget_free_endpoints due to race condition
In the Linux kernel, the following vulnerability has been resolved:
usb: dwc3: gadget: Fix use-after-free in dwc3_gadget_free_endpoints due to race condition
In dwc3_gadget_init_endpoint, &dep->nostream_work is bound with
dwc3_nostream_work, and dwc3_gadget_endpoint_stream_event can queue
this delayed work on system_percpu_wq when a DEPEVT_STREAM_NOSTREAM
event is received.
If we remove the gadget, dwc3_gadget_free_endpoints makes cleanup and
the memory allocated for dep with kzalloc() is released by kfree(dep),
while the delayed work mentioned above may still be pending or
running. The sequence of operations that may lead to a UAF bug is
usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: at91_udc: drain polled-VBUS timer/work before udc is freed
In polled-VBUS mode (board.vbus_pin && board.vbus_polled), probe arms a
self-restarting cycle: at91_vbus_timer() schedules vbus_timer_work, and
at91_vbus_timer_work() calls at91_vbus_update() and re-arms the timer via
mod_timer(). Both recover the same udc through container_of and dereference
it on every iteration.
Neither teardown path cancels this cycle. udc is devm-allocated, so it is
freed after at91udc_remove() returns, and is likewise freed when probe
fails and devres runs. A timer callback or wo
usb: typec: thunderbolt: Disable work before freeing tbt on remove
In the Linux kernel, the following vulnerability has been resolved:
usb: typec: thunderbolt: Disable work before freeing tbt on remove
tbt_altmode_remove() drops the plug and cable references without
draining tbt->work. The work function dereferences those references,
and can also requeue itself in its error path. The VDM callbacks can
queue the same work item.
Disable and drain tbt->work before dropping the references. This waits
for an existing invocation and prevents subsequent schedule_work()
calls from queueing it during teardown.
This issue was found by an in-house static analysis tool and confirmed
by manual code review.