CVE-2022-48743

What it actually does

Inconsistent hardware descriptors in the amd-xgbe driver can trigger skb length underflow checks in skbuff.h, invoking BUG_ON() and causing kernel panic.

Why it matters to the business

Systems using affected AMD network hardware experience intermittent crashes and reboots, leading to unplanned downtime and potential data loss during network activity.

How an attack unfolds

An attacker sends network traffic crafted to produce inconsistent hardware descriptors in the amd-xgbe driver, causing skb length underflow detection and a subsequent kernel panic on the target system.

How to fix it

Upgrade Linux kernel to version 4.9.300 or apply the fix from commit 9924c80bd484340191e586110ca22bff23a49f2e in stable trees; drop packets exhibiting descriptor length inconsistencies until patched.

How to confirm the fix worked

Confirm kernel version is at or above 4.9.300 or contains commit 9924c80bd484340191e586110ca22bff23a49f2e; test by replaying traffic patterns that previously triggered underflow conditions and verify no BUG_ON occurs.

Typical attack path

1. Identify systems exposing amd-xgbe network interfaces
2. Transmit specially crafted or high-volume network frames to trigger descriptor inconsistencies
3. Trigger skb length underflow and BUG_ON() resulting in kernel panic

How to detect it

Review kernel logs and dmesg output for BUG_ON messages originating from include/linux/skbuff.h related to skb length underflow on amd-xgbe interfaces.

What your security team should do

• Prioritize kernel upgrades on all systems using amd-xgbe hardware within the next maintenance window
• Monitor kernel logs for skbuff underflow panics as an interim detection measure
• Apply vendor-supplied stable kernel updates containing the referenced commit