Linux Kernel 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.

The affected component is the stmmac network driver in the mainline Linux kernel (drivers/net/ethernet/stmicro/stmmac). No CPE strings or explicit version ranges were provided in the input; the four referenced git.kernel.org/stable commits (1aa319e, 63fbe0e, 719fcdf, ee0aace) indicate the fix was backported across multiple stable branches, implying a broad range of kernel versions with the CoE Rx path is affected until patched. Impact is limited to platforms whose Ethernet is driven by stmmac with hardware checksum offload enabled. Refer to the kernel stable tree commits for the precise affected/patched versions per branch, as no single vendor advisory URL or fixed tag was supplied.