Linux Kernel Vulnerability in bcmgenet Control Block Handling

CVE-2026-99192

What is CVE-2026-99192?

A vulnerability has been identified in the Linux kernel's bcmgenet module, where improper handling of socket buffer (skb) control blocks can lead to transmission issues. The bcmgenet driver stores critical data—such as first_cb, last_cb, and bytes_sent—in the skb control block, allowing for potential overwrites during packet transmission. When utilizing the ether_setup function with IFF_TX_SKB_SHARING enabled, the reuse of shared skb while prior copies remain in the transmission ring can result in incomplete crediting of bytes sent. Consequently, this can stall the bandwidth queue length (BQL) until a watchdog resets the queue. The issue can be reproduced in packet generation scenarios using the pktgen tool, where cloning skb without appropriate isolation causes transmission inefficiencies.

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