CVE-2025-40264: Critical be2net Driver Vulnerability Patched in Linux Kernel

Overview

CVE-2025-40264 is a vulnerability in the Linux kernel’s be2net network driver. This flaw is a NULL pointer dereference that can occur during packet processing in specific scenarios involving OS2BMC. This blog post provides a comprehensive overview of the vulnerability, including technical details, potential impact, and mitigation steps.

Technical Details

The vulnerability stems from the be_send_pkt_to_bmc() function being called with a NULL wrb_params argument from the be_insert_vlan_in_pkt() function. This can lead to a NULL pointer dereference when the driver attempts to process a workaround for a specific type of packet. The root cause is that be_insert_vlan_in_pkt() doesn’t correctly pass the wrb_params obtained from be_xmit() to be_send_pkt_to_bmc() in OS2BMC situations. This issue was introduced to address a Tx stall bug. With a NULL wrb_params, dereferencing becomes inevitable when the workaround logic is invoked.

CVSS Analysis

Currently, there is no CVSS score assigned to CVE-2025-40264. This may be due to the complexity of triggering the vulnerability and the specific hardware requirements. Further analysis is required to determine the exact severity of this issue.

Possible Impact

While the exact impact is still being evaluated, a NULL pointer dereference in the kernel can lead to:

• **Kernel Panic:** The system may crash, resulting in a denial-of-service.
• **System Instability:** Unexpected behavior and potential data corruption.
• **Potential for Exploitation:** Although unlikely, a skilled attacker might be able to leverage this vulnerability to gain further access or execute arbitrary code, especially if combined with other vulnerabilities.

Mitigation and Patch Steps

The vulnerability has been addressed in recent Linux kernel updates. The fix involves correctly passing the wrb_params from be_xmit() to be_send_pkt_to_bmc(), ensuring that the driver has valid parameters when processing these specific packets.

To mitigate this vulnerability, users should:

1. **Update Kernel:** Upgrade to the latest stable Linux kernel version that includes the fix.
2. **Apply Patches:** If a full kernel upgrade is not immediately feasible, apply the relevant patch from the kernel git repository to the existing kernel.
3. **Monitor Systems:** Keep a close watch on systems running the affected be2net driver for any signs of instability or unexpected behavior.

References

Kernel Commit 1ecd86ec6efddb59a10c927e8e679f183bb9113e
Kernel Commit 48d59b60dd5d7e4c48c077a2008c9dcd7b59bdfe
Kernel Commit 4c4741f6e7f2fa4e1486cb61e1c15b9236ec134d
Kernel Commit 7d277a7a58578dd62fd546ddaef459ec24ccae36
Kernel Commit ce0a3699244aca3acb659f143c9cb1327b210f89