CVE-2025-40337

In the Linux kernel, the following vulnerability has been resolved:

net: stmmac: Correctly handle Rx checksum offload errors

The stmmac_rx function would previously set skb->ip_summed to CHECKSUM_UNNECESSARY if hardware checksum offload (CoE) was enabled and the packet was of a known IP ethertype.

However, this logic failed to check if the hardware had actually reported a checksum error. The hardware status, indicating a header or payload checksum failure, was being ignored at this stage. This could cause corrupt packets to be passed up the network stack as valid.

This patch corrects the logic by checking the csum_none status flag, which is set when the hardware reports a checksum error. If this flag is set, skb->ip_summed is now correctly set to CHECKSUM_NONE, ensuring the kernel's network stack will perform its own validation and properly handle the corrupt packet.

This vulnerability does not affect supported Red Hat Enterprise Linux releases as the susceptible code is not present. The underlying issue is isolated to the STMicroelectronics Ethernet (stmmac) controller driver, which is typically found in specialized embedded systems and system-on-chip architectures rather than enterprise server environments. Under affected configurations, the flaw would allow packets with invalid hardware checksums to bypass network stack verification, requiring an attacker to be on an adjacent network path capable of transmitting malformed frames.