Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ipv6: prevent possible UaF in addrconf_permanent_addr()
The mentioned helper try to warn the user about an exceptional
condition, but the message is delivered too late, accessing the ipv6
after its possible deletion.
Reorder the statement to avoid the possible UaF; while at it, place the
warning outside the idev->lock as it needs no protection.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
comedi: Reinit dev->spinlock between attachments to low-level drivers
`struct comedi_device` is the main controlling structure for a COMEDI
device created by the COMEDI subsystem. It contains a member `spinlock`
containing a spin-lock that is initialized by the COMEDI subsystem, but
is reserved for use by a low-level driver attached to the COMEDI device
(at least since commit 25436dc9d84f ("Staging: comedi: remove RT
code")).
Some COMEDI devices (those created on initialization of the COMEDI
subsystem when the "comedi.comedi_num_legacy_minors" parameter is
non-zero) can be attached to different low-level drivers over their
lifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in
inconsistent lock states being reported when there is a mismatch in the
spin-lock locking levels used by each low-level driver to which the
COMEDI device has been attached. Fix it by reinitializing
`dev->spinlock` before calling the low-level driver's `attach` function
pointer if `CONFIG_LOCKDEP` is enabled.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback
SCX_KICK_WAIT busy-waits in kick_cpus_irq_workfn() using
smp_cond_load_acquire() until the target CPU's kick_sync advances. Because
the irq_work runs in hardirq context, the waiting CPU cannot reschedule and
its own kick_sync never advances. If multiple CPUs form a wait cycle, all
CPUs deadlock.
Replace the busy-wait in kick_cpus_irq_workfn() with resched_curr() to
force the CPU through do_pick_task_scx(), which queues a balance callback
to perform the wait. The balance callback drops the rq lock and enables
IRQs following the sched_core_balance() pattern, so the CPU can process
IPIs while waiting. The local CPU's kick_sync is advanced on entry to
do_pick_task_scx() and continuously during the wait, ensuring any CPU that
starts waiting for us sees the advancement and cannot form cyclic
dependencies.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
USB: dummy-hcd: Fix locking/synchronization error
Syzbot testing was able to provoke an addressing exception and crash
in the usb_gadget_udc_reset() routine in
drivers/usb/gadgets/udc/core.c, resulting from the fact that the
routine was called with a second ("driver") argument of NULL. The bad
caller was set_link_state() in dummy_hcd.c, and the problem arose
because of a race between a USB reset and driver unbind.
These sorts of races were not supposed to be possible; commit
7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"),
along with a few followup commits, was written specifically to prevent
them. As it turns out, there are (at least) two errors remaining in
the code. Another patch will address the second error; this one is
concerned with the first.
The error responsible for the syzbot crash occurred because the
stop_activity() routine will sometimes drop and then re-acquire the
dum->lock spinlock. A call to stop_activity() occurs in
set_link_state() when handling an emulated USB reset, after the test
of dum->ints_enabled and before the increment of dum->callback_usage.
This allowed another thread (doing a driver unbind) to sneak in and
grab the spinlock, and then clear dum->ints_enabled and dum->driver.
Normally this other thread would have to wait for dum->callback_usage
to go down to 0 before it would clear dum->driver, but in this case it
didn't have to wait since dum->callback_usage had not yet been
incremented.
The fix is to increment dum->callback_usage _before_ calling
stop_activity() instead of after. Then the thread doing the unbind
will not clear dum->driver until after the call to
usb_gadget_udc_reset() safely returns and dum->callback_usage has been
decremented again.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
cpufreq: governor: fix double free in cpufreq_dbs_governor_init() error path
When kobject_init_and_add() fails, cpufreq_dbs_governor_init() calls
kobject_put(&dbs_data->attr_set.kobj).
The kobject release callback cpufreq_dbs_data_release() calls
gov->exit(dbs_data) and kfree(dbs_data), but the current error path
then calls gov->exit(dbs_data) and kfree(dbs_data) again, causing a
double free.
Keep the direct kfree(dbs_data) for the gov->init() failure path, but
after kobject_init_and_add() has been called, let kobject_put() handle
the cleanup through cpufreq_dbs_data_release().
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
netfilter: flowtable: strictly check for maximum number of actions
The maximum number of flowtable hardware offload actions in IPv6 is:
* ethernet mangling (4 payload actions, 2 for each ethernet address)
* SNAT (4 payload actions)
* DNAT (4 payload actions)
* Double VLAN (4 vlan actions, 2 for popping vlan, and 2 for pushing)
for QinQ.
* Redirect (1 action)
Which makes 17, while the maximum is 16. But act_ct supports for tunnels
actions too. Note that payload action operates at 32-bit word level, so
mangling an IPv6 address takes 4 payload actions.
Update flow_action_entry_next() calls to check for the maximum number of
supported actions.
While at it, rise the maximum number of actions per flow from 16 to 24
so this works fine with IPv6 setups.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
crypto: caam - fix overflow on long hmac keys
When a key longer than block size is supplied, it is copied and then
hashed into the real key. The memory allocated for the copy needs to
be rounded to DMA cache alignment, as otherwise the hashed key may
corrupt neighbouring memory.
The copying is performed using kmemdup, however this leads to an overflow:
reading more bytes (aligned_len - keylen) from the keylen source buffer.
Fix this by replacing kmemdup with kmalloc, followed by memcpy.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
x86/kexec: Disable KCOV instrumentation after load_segments()
The load_segments() function changes segment registers, invalidating GS base
(which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any
subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins
crashing the kernel in an endless loop.
To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented
kernel:
$ kexec -l /boot/otherKernel
$ kexec -e
The real-world context for this problem is enabling crash dump collection in
syzkaller. For this, the tool loads a panic kernel before fuzzing and then
calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC
and CONFIG_KCOV to be enabled simultaneously.
Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc())
is also undesirable as it would introduce an extra performance overhead.
Disabling instrumentation for the individual functions would be too fragile,
so disable KCOV instrumentation for the entire machine_kexec_64.c and
physaddr.c. If coverage-guided fuzzing ever needs these components in the
future, other approaches should be considered.
The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported
there.
[ bp: Space out comment for better readability. ]
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
thermal: core: Fix thermal zone device registration error path
If thermal_zone_device_register_with_trips() fails after registering
a thermal zone device, it needs to wait for the tz->removal completion
like thermal_zone_device_unregister(), in case user space has managed
to take a reference to the thermal zone device's kobject, in which case
thermal_release() may not be called by the error path itself and tz may
be freed prematurely.
Add the missing wait_for_completion() call to the thermal zone device
registration error path.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
USB: dummy-hcd: Fix interrupt synchronization error
This fixes an error in synchronization in the dummy-hcd driver. The
error has a somewhat involved history. The synchronization mechanism
was introduced by commit 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous
synchronization change"), which added an emulated "interrupts enabled"
flag together with code emulating synchronize_irq() (it waits until
all current handler callbacks have returned).
But the emulated interrupt-disable occurred too late, after the driver
containing the handler callback routines had been told that it was
unbound and no more callbacks would occur. Commit 4a5d797a9f9c ("usb:
gadget: dummy_hcd: fix gpf in gadget_setup") tried to fix this by
moving the synchronize_irq() emulation code from dummy_stop() to
dummy_pullup(), which runs before the unbind callback.
There still were races, though, because the emulated interrupt-disable
still occurred too late. It couldn't be moved to dummy_pullup(),
because that routine can be called for reasons other than an impending
unbind. Therefore commits 7dc0c55e9f30 ("USB: UDC core: Add
udc_async_callbacks gadget op") and 04145a03db9d ("USB: UDC: Implement
udc_async_callbacks in dummy-hcd") added an API allowing the UDC core
to tell dummy-hcd exactly when emulated interrupts and their callbacks
should be disabled.
That brings us to the current state of things, which is still wrong
because the emulated synchronize_irq() occurs before the emulated
interrupt-disable! That's no good, beause it means that more emulated
interrupts can occur after the synchronize_irq() emulation has run,
leading to the possibility that a callback handler may be running when
the gadget driver is unbound.
To fix this, we have to move the synchronize_irq() emulation code yet
again, to the dummy_udc_async_callbacks() routine, which takes care of
enabling and disabling emulated interrupt requests. The
synchronization will now run immediately after emulated interrupts are
disabled, which is where it belongs.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-08