UBUNTU-CVE-2026-90208: Low severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: clocksource/drivers/samsungpwm: Switch to rawspinlockt type Samsung PWM timer might be used as a clock source on some legacy systems. When PREEMPTRT is enabled on ARM, regular spinlock is converted to a sleeping lock (mutex-based), which must not be used in atomic context such as hard interrupt handlers. Switch the samsungpwmlock to the rawspinlock, which remains a true non-sleeping spinlock even under PREEMPTRT.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
Upgrade
ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Configuration
Change samsung_pwm_lock from a regular spinlock to raw_spinlock_t so it remains a non-sleeping spinlock under PREEMPT_RT.
Linux kernel Samsung PWM timer driver samsung_pwm_lock type = raw_spinlock_t
Event History
Frequently Asked Questions
Which systems are most likely to be exposed to this issue?
The issue applies where the Samsung PWM timer is used as a clock source, particularly on legacy ARM systems running a kernel with PREEMPT_RT enabled. The affected Ubuntu kernel package families listed are linux, linux-fips, linux-aws, linux-azure, linux-aws-fips, linux-azure-fips, linux-gcp, and linux-gcp-fips.
What condition triggers the problem?
With PREEMPT_RT enabled on ARM, the regular Samsung PWM lock is converted into a mutex-based sleeping lock. If the PWM timer is used as a clock source and that lock is taken from hard interrupt context, the sleeping lock is unsafe in that atomic context.
What is the remediation?
Use a kernel containing the change that converts samsung_pwm_lock from a regular spinlock to a raw_spinlock_t. A raw spinlock remains non-sleeping under PREEMPT_RT and is suitable for hard interrupt contexts.