CVE-2025-21676 net: fec: handle page_pool_dev_alloc_pages error
A null pointer dereference in the Linux kernel FEC network driver can cause a system crash when memory allocation fails under pressure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-21676?
CVE-2025-21676 is a high-severity vulnerability in Linux kernel, published on 31 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: fec: handle page_pool_dev_alloc_pages error
The fec_enet_update_cbd function calls page_pool_dev_alloc_pages but did not handle the case when it returned NULL. There was a WARN_ON(!new_page) but it would still proceed to use the NULL pointer and then crash.
This case does seem somewhat rare but when the system is under memory pressure it can happen. One case where I can duplicate this with some frequency is when writing over a smbd share to a SATA HDD attached to an imx6q.
Setting /proc/sys/vm/min_free_kbytes to higher values also seems to solve the problem for my test case. But it still seems wrong that the fec driver ignores the memory allocation error and can crash.
This commit handles the allocation error by dropping the current packet.
Weakness: CWE-476
Which versions are affected by CVE-2025-21676?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21676?
Apply the vendor's patch.
Is CVE-2025-21676 being exploited?
There is no known exploitation of CVE-2025-21676 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-56387, BELL-CVE-2025-21676, DEBIAN-CVE-2025-21676, GHSA-2cvp-cxm8-hg6v, ROOT-OS-DEBIAN-12-CVE-2025-21676, UBUNTU-CVE-2025-21676.