CVE-2025-21676

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.

This vulnerability is rated as Moderate because an attacker would need local access to cause severe memory exhaustion on a system using specific hardware, leading to a denial of service via a kernel null-pointer dereference. Supported Red Hat Enterprise Linux releases are not affected as the vulnerable code within the Freescale Fast Ethernet Controller driver was introduced in newer upstream kernels and is not present in Red Hat enterprise kernels. Additionally, the issue is restricted to hardware platforms utilizing this specific Ethernet controller.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.