CVE-2025-40346 arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
A null pointer dereference in the Linux kernel's CPU topology parsing can cause a system crash, requiring a kernel patch to fix.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40346?
CVE-2025-40346 is a vulnerability in Linux, published on 16 Dec 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:
arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Fix incorrect use of PTR_ERR_OR_ZERO() in topology_parse_cpu_capacity() which causes the code to proceed with NULL clock pointers. The current logic uses !PTR_ERR_OR_ZERO(cpu_clk) which evaluates to true for both valid pointers and NULL, leading to potential NULL pointer dereference in clk_get_rate().
Per include/linux/err.h documentation, PTR_ERR_OR_ZERO(ptr) returns: "The error code within @ptr if it is an error pointer; 0 otherwise."
This means PTR_ERR_OR_ZERO() returns 0 for both valid pointers AND NULL pointers. Therefore !PTR_ERR_OR_ZERO(cpu_clk) evaluates to true (proceed) when cpu_clk is either valid or NULL, causing clk_get_rate(NULL) to be called when of_clk_get() returns NULL.
Replace with !IS_ERR_OR_NULL(cpu_clk) which only proceeds for valid pointers, preventing potential NULL pointer dereference in clk_get_rate().
Which versions are affected by CVE-2025-40346?
How do I fix CVE-2025-40346?
Apply the vendor's patch.
Is CVE-2025-40346 being exploited?
There is no known exploitation of CVE-2025-40346 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40346, DEBIAN-CVE-2025-40346, GHSA-3qw8-vgp2-684r, ROOT-OS-UBUNTU-2404-CVE-2025-40346, UBUNTU-CVE-2025-40346.