CVE-2025-38633 clk: spacemit: mark K1 pll1_d8 as critical
A logic error in the Linux kernel clock driver allows disabling a critical parent clock, causing a system hang and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38633?
CVE-2025-38633 is a medium-severity denial of service vulnerability in Linux kernel, published on 22 Aug 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
clk: spacemit: mark K1 pll1_d8 as critical
The pll1_d8 clock is enabled by the boot loader, and is ultimately a parent for numerous clocks, including those used by APB and AXI buses. Guodong Xu discovered that this clock got disabled while responding to getting -EPROBE_DEFER when requesting a reset controller.
The needed clock (CLK_DMA, along with its parents) had already been enabled. To respond to the probe deferral return, the CLK_DMA clock was disabled, and this led to parent clocks also reducing their enable count. When the enable count for pll1_d8 was decremented it became 0, which caused it to be disabled. This led to a system hang.
Marking that clock critical resolves this by preventing it from being disabled.
Define a new macro CCU_FACTOR_GATE_DEFINE() to allow clock flags to be supplied for a CCU_FACTOR_GATE clock.
Which versions are affected by CVE-2025-38633?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38633?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-38633 being exploited?
There is no known exploitation of CVE-2025-38633 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38633, GHSA-xp55-qmgg-q2rh, UBUNTU-CVE-2025-38633.