CVE-2022-48805: Linux Kernel Buffer Overflow Vulnerability

CVE-2022-48805 Overview

CVE-2022-48805 is an out-of-bounds access vulnerability in the Linux kernel's ax88179_178a USB network driver. The vulnerability exists in the ax88179_rx_fixup() function, which handles packet reception from AX88179 and AX88178A USB Ethernet adapters. A malicious or defective USB device can trigger multiple out-of-bounds memory accesses, potentially leading to information disclosure, data corruption, or system compromise.

Critical Impact

A malicious USB device can exploit this vulnerability to leak sensitive kernel heap data via crafted network packets and potentially achieve out-of-bounds writes on little-endian systems.

Affected Products

• Linux Kernel (multiple versions affected)
• Linux Kernel 5.17-rc1
• Linux Kernel 5.17-rc2
• Linux Kernel 5.17-rc3

Discovery Timeline

• 2024-07-16 - CVE CVE-2022-48805 published to NVD
• 2025-03-06 - Last updated in NVD database

Technical Details for CVE-2022-48805

Vulnerability Analysis

The vulnerability resides in the ax88179_rx_fixup() function within the USB network driver for AX88179 and AX88178A chipsets. This function processes incoming network packets from USB Ethernet adapters but fails to properly validate boundaries when handling packet metadata and payload data.

Three distinct out-of-bounds access conditions have been identified:

1. Metadata Array Overflow: The metadata array accessed at offsets hdr_off to hdr_off+2*pkt_cnt can extend beyond buffer boundaries, causing out-of-bounds reads and, on big-endian systems, out-of-bounds endianness conversions.

2. Packet/Metadata Overlap: A maliciously crafted packet can overlap with the metadata array, causing subsequent out-of-bounds endianness flips to corrupt data in SKBs (socket buffers) that have already been passed to the network stack.

3. SKB Tail Manipulation: A packet SKB can be constructed with its tail pointer positioned far beyond its actual end, causing out-of-bounds heap data to be treated as part of the SKB's data payload.

The vulnerability can be exploited locally by connecting a malicious USB device to the target system. Successful exploitation has been demonstrated to leak kernel heap data through crafted ICMPv6 Echo Request/Reply exchanges.

Root Cause

The root cause is insufficient boundary checking and validation in the ax88179_rx_fixup() function. The driver trusts packet metadata provided by the USB device without verifying that the indicated packet counts, offsets, and sizes fall within the bounds of the received data buffer. This allows an attacker-controlled USB device to specify malicious values that cause the driver to access memory outside the intended buffer boundaries.

Attack Vector

Exploitation requires local access to connect a malicious USB device to the target system. The attack proceeds as follows:

1. The attacker connects a specially crafted USB device emulating an AX88179/AX88178A USB Ethernet adapter
2. The malicious device sends packets with manipulated metadata indicating invalid packet counts or offsets
3. When the kernel's ax88179_rx_fixup() function processes these packets, it performs out-of-bounds memory operations
4. On big-endian systems, OOB endianness flips corrupt adjacent memory
5. The attacker can craft ICMPv6 Echo Requests that trigger responses containing leaked kernel heap data
6. On little-endian systems, additional exploitation through IP options processing may enable out-of-bounds writes via skb_cow() triggering

The vulnerability demonstrates how USB devices, which are often implicitly trusted, can be weaponized to compromise kernel memory safety.

Detection Methods for CVE-2022-48805

Indicators of Compromise

• Unexpected USB Ethernet adapter connections, particularly AX88179 or AX88178A chipsets
• Kernel log messages indicating memory corruption or out-of-bounds access in the ax88179_178a driver
• Unusual ICMPv6 traffic patterns from systems with USB Ethernet adapters
• Kernel OOPS or panic events related to USB network driver processing

Detection Strategies

• Monitor USB device connection events for unexpected AX88179/AX88178A Ethernet adapters using udevadm monitor or similar tools
• Implement kernel KASAN (Kernel Address Sanitizer) in development/testing environments to detect out-of-bounds accesses
• Deploy endpoint detection rules to alert on suspicious USB device enumeration patterns
• Review kernel logs (dmesg) for anomalies in the ax88179_178a driver module

Monitoring Recommendations

• Enable USB device auditing to track all USB device connections with timestamps and device descriptors
• Configure kernel logging verbosity for the ax88179_178a module during security-sensitive operations
• Implement network traffic analysis to identify anomalous ICMPv6 patterns that may indicate exploitation attempts

How to Mitigate CVE-2022-48805

Immediate Actions Required

• Update the Linux kernel to a patched version that includes the boundary checking fixes
• Restrict physical USB port access on sensitive systems through physical security controls
• Disable USB ports where not required using BIOS/UEFI settings or kernel parameters
• Consider using USB device whitelisting via USBGuard to prevent unauthorized USB Ethernet adapters

Patch Information

Linux kernel patches have been released across multiple stable branches. The following commits contain the fix:

• Kernel Git Commit 1668781e
• Kernel Git Commit 57bc3d3a
• Kernel Git Commit 63f0cfb3
• Kernel Git Commit 711b6bf3
• Kernel Git Commit 758290de
• Kernel Git Commit 9681823f
• Kernel Git Commit a0fd5492
• Kernel Git Commit ffd0393a

Workarounds

• Blacklist the ax88179_178a kernel module if AX88179/AX88178A USB Ethernet adapters are not required
• Implement USB device whitelisting using USBGuard to block unauthorized USB Ethernet adapters
• Disable USB controller access for unprivileged users through system hardening measures

# Blacklist the vulnerable driver module
echo "blacklist ax88179_178a" | sudo tee /etc/modprobe.d/blacklist-ax88179.conf

# Unload the module if currently loaded
sudo modprobe -r ax88179_178a

# Verify module is not loaded
lsmod | grep ax88179