CVE-2026-90338
Low risk· EPSS 10%Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
A vulnerability exists in the Linux kernel's amba-pl011 serial console driver. The pl011_console_write_atomic() function runs in nbcon atomic context and calls clk_enable(), which under PREEMPT_RT can sleep, triggering a "sleeping function called from invalid context" bug. This affects arm32 and arm64 Device Tree SoCs where the UART uses a common-clk managed clock.
Risk Assessment
On PREEMPT_RT systems, an atomic-context printk (e.g., from NMI) can cause a kernel bug and system hang. It may also lead to an unsafe NMI acquisition of the common-clock enable_lock.
Recommendation
Update the Linux kernel to a version containing the fix that moves clock enabling to pl011_console_setup() and releases it in the console .exit() callback. If updating is not possible, avoid PREEMPT_RT configurations with pl011 console or limit atomic-context printk calls.
Other vulnerabilities in Linux kernel
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- CVE-2026-99258Unknown
In the Linux kernel, hv_apicid_to_vp_index() uses per-CPU hypercall input and output pages. In an SEV-SNP CoCo VM without a paravisor the output page is not allocated, so the hypervisor stores the resulting VP index into memory not allocated by the guest. The fix uses the input page for both input and output.
- CVE-2026-99257Unknown
In the Linux kernel, the shared GPIO mechanism based on platform lookup tables requires an associated struct device. An fwnode-based lookup with no associated device currently causes a NULL-pointer dereference. The fix adds a check that lets the kernel gracefully handle this situation with an error.
- CVE-2026-99256Unknown
In the Linux kernel, the dm cache module used a rw_semaphore for background_work_lock, although write locks on rw_semaphores have strict owner semantics. The locking process was not always the same as the unlocking one, triggering a warning with CONFIG_DEBUG_RWSEMS during suspend/resume of a cache device. The fix replaces the rw_semaphore with a spinlock and a wait queue.
- CVE-2026-99251Unknown
In the Linux kernel, init_vp_index() contains a retry loop that strips CPUs from a node if they are already in the allocated cpumask or outside the HK_TYPE_MANAGED_IRQ housekeeping cpumask. If the housekeeping cpumask contains no CPU in that node, the loop becomes infinite. The fix skips NUMA nodes with no housekeeping CPU and aborts early when no online housekeeping CPUs exist.
- CVE-2026-99250Unknown
In the Linux kernel, the NBCON console printing kthreads are started very early during boot via early_initcall(). Asynchronously enabling/disabling interrupts during early boot may interfere with early SMP setup on some hardware platforms, causing hangs. The fix postpones kthread startup until after all arch initcalls have completed.
- CVE-2026-99249Unknown
In the Linux kernel, zap_pid_ns_processes() waiting for PID namespace cleanup was not freezable. A tracer outside the namespace that does not reap its traced zombies keeps PIDs allocated, making the wait unbounded and causing every suspend attempt to fail. The fix makes the wait loops use TASK_FREEZABLE states so the freezer can freeze waiting tasks.
- CVE-2026-99248Unknown
In the Linux kernel, the i2c: xiic driver was changed to restore non-managed runtime PM instead of the devres-based approach to fix a clk WARN flood. The managed release tore down runtime PM in the wrong order, causing the clock to be disabled twice and triggering "clkN already disabled" warnings on every teardown.
- CVE-2026-99247Unknown
In the Linux kernel, if trace buffer allocation fails during early boot, tracing_disabled remains set and the global trace array events list stays uninitialized. tracer_init_tracefs_work_func() runs asynchronously without checking this state and calls event_trace_init() and init_tracer_tracefs(), leading to a NULL pointer dereference Oops during boot. The fix checks tracing_disabled at the start of the work function.
- CVE-2026-99215Unknown
In the Linux kernel power supply subsystem, a use-after-free vulnerability exists. If a power supply is unregistered while its external_power_changed() callback is still running, the driver may free data that the callback is still accessing, leading to a kernel crash (NULL pointer dereference).
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: serial: amba-pl011: keep console clock enabled for atomic writes pl011_console_write_atomic() runs from nbcon atomic context, where sleeping is not allowed. It calls clk_enable(), which takes the common-clk enable_lock. Under PREEMPT_RT that is a sleeping lock: clk_enable_lock() first tries spin_trylock_irqsave(), but on contention falls back to spin_lock_irqsave(). Therefore, an atomic-context printk on an RT kernel with a clk-backed pl011 can trip: BUG: sleeping function called from invalid context at spinlock_rt.c:48 __might_resched from rt_spin_lock rt_spin_lock from clk_enable_lock clk_enable_lock from clk_enable clk_enable from pl011_console_write_atomic ... from vprintk_emit This was found and reproduced on PREEMPT_RT. Arm32 and arm64 DT SoCs are affected; arm64 SBSA/ACPI has no clk, so clk_enable(NULL) short-circuits before the lock. In addition, write_atomic() may be invoked from NMI context and is documented to avoid locking. Removing clk_enable() from the callback also avoids a potentially unsafe NMI acquisition of the common-clock enable_lock. An nbcon atomic-capable console must be printable from any context, so the clock cannot be gated between writes. Enable the clock while the console is available for output: use clk_prepare_enable() in pl011_console_setup(), release it via clk_disable_unprepare() in the console .exit() callback, and drop the per-write clk_enable()/clk_disable() pairs from write_atomic() and write_thread(). When printk suspends consoles, drop the reference after uart_suspend_port() stops console access and restore it before uart_resume_port() -- but only if suspend actually marked the port suspended (a wake-capable tty stays running and must keep its clock), and keep it when console_suspend_enabled is false so no_console_suspend works. The active power cost of keeping the clock enabled is platform-dependent: none where the UART clock is a fixed always-on oscillator, real where it is a gateable clock branch, which then cannot be gated (nor possibly can its parent clocks) while the console is available for output. When serial core actually suspends the port, the reference is released so the clock provider can gate the clock tree.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS