A vulnerability within the Linux kernel has been resolved, addressing an issue in the geneve_xmit_skb() function, which is part of the Generic Network Virtualization Encapsulation (Geneve) module. This vulnerability could have potentially led to unpredictable behavior or system crashes.

Vulnerability Details

The geneve_xmit_skb() function in the Linux kernel previously assumed that the MAC header was set in the output path. However, this assumption has been determined to be incorrect, leading to a code update that employs skb_eth_hdr() instead of eth_hdr() to resolve the issue. This change should provide a more reliable approach when accessing Ethernet headers in kernel code.

Sysbot, an automated vulnerability reporting system, initially reported the following warning message:

WARNING: CPU:  PID: 11635 at include/linux/skbuff.h:3052 skb_mac_header include/linux/skbuff.h:3052 [inline]
WARNING: CPU:  PID: 11635 at include/linux/skbuff.h:3052 eth_hdr include/linux/if_ether.h:24 [inline]
WARNING: CPU:  PID: 11635 at include/linux/skbuff.h:3052 geneve_xmit_skb drivers/net/geneve.c:898 [inline]
WARNING: CPU:  PID: 11635 at include/linux/skbuff.h:3052 geneve_xmit+x4c38/x573 drivers/net/geneve.c:1039
Modules linked in:
CPU:  UID:  PID: 11635 Comm: syz.4.1423 Not tainted 6.12.-syzkaller-10296-gaaf20f870da #
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024

To better understand the specifics of the vulnerability, one can examine the official Linux kernel source code and the associated networking headers. This can provide a deeper understanding of how Geneve operates within the Linux kernel and how this particular issue manifested itself.

Exploit Details

Although specific details on exploiting this vulnerability are not available, improper handling of Ethernet headers and assumptions about MAC header settings in kernel code can lead to erratic behavior, system crashes, or other negative outcomes. It is important to ensure that your kernel is up-to-date and incorporates the latest security patches in order to minimize potential risks.

In summary, the vulnerability in the Linux kernel's geneve_xmit_skb() function, assigned CVE-2024-56636, has been resolved, providing a more robust implementation for handling network virtualization encapsulation. By examining the source code, networking headers, and sysbot reports, one can better understand the implications of this vulnerability and take the necessary steps to protect their systems.

Timeline

Published on: 12/27/2024 15:15:23 UTC
Last modified on: 01/20/2025 06:24:41 UTC