CVE-2022-25258: Linux Kernel Buffer Overflow Vulnerability

CVE-2022-25258 Overview

CVE-2022-25258 is a memory corruption vulnerability discovered in the Linux kernel's USB Gadget subsystem, specifically in the drivers/usb/gadget/composite.c file. The vulnerability exists in versions prior to 5.16.10 and stems from inadequate validation of interface OS descriptor requests. Attackers with physical access to a vulnerable system can craft malicious requests using large array indices or requests that result in NULL function pointer retrieval, potentially causing memory corruption and system instability.

Critical Impact

Physical access exploitation can lead to memory corruption in the Linux kernel USB Gadget subsystem, potentially causing denial of service conditions on affected systems including enterprise storage appliances and virtualization platforms.

Affected Products

• Linux Kernel (versions before 5.16.10)
• Fedora 35
• Debian Linux 9.0, 10.0, 11.0
• NetApp Active IQ Unified Manager (VMware vSphere)
• NetApp H300S/H500S/H700S/H410S/H410C Firmware

Discovery Timeline

• February 16, 2022 - CVE-2022-25258 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-25258

Vulnerability Analysis

The vulnerability resides in the USB Gadget composite driver's handling of OS descriptor requests. The affected code path processes interface-related requests without properly validating the interface index or checking for NULL function pointers before use. When processing requests with the w_value parameter, the code extracts an interface number but fails to verify that this value falls within acceptable bounds (less than MAX_CONFIG_INTERFACES) or that the corresponding interface pointer is valid.

This lack of validation creates two distinct attack scenarios: first, an attacker can provide a large array index that exceeds the bounds of the interface array, leading to out-of-bounds memory access; second, the code may attempt to use a NULL function pointer when the requested interface does not exist, resulting in a null pointer dereference condition.

Root Cause

The root cause is a missing bounds check and NULL pointer validation in drivers/usb/gadget/composite.c. The code directly uses the interface number derived from the w_value parameter to index into the os_desc_cfg->interface array without verifying that:

1. The interface index is less than MAX_CONFIG_INTERFACES
2. The corresponding interface pointer is not NULL

This is classified as CWE-476 (NULL Pointer Dereference), where the application dereferences a pointer that it expects to be valid but is NULL, leading to a crash or potentially exploitable condition.

Attack Vector

The attack requires physical access to the target device (Attack Vector: Physical). An attacker must be able to connect a malicious USB device or manipulate USB communications to send specially crafted OS descriptor requests to the vulnerable USB Gadget subsystem. The attack does not require user interaction or privileges, and can be executed with low complexity once physical access is obtained.

The attacker crafts a USB request with a manipulated w_value parameter containing an interface index that either exceeds the valid range or references a non-existent interface, triggering the memory corruption or NULL pointer dereference.

 				if (w_index != 0x5 || (w_value >> 8))
 					break;
 				interface = w_value & 0xFF;
+				if (interface >= MAX_CONFIG_INTERFACES ||
+				    !os_desc_cfg->interface[interface])
+					break;
 				buf[6] = w_index;
 				count = count_ext_prop(os_desc_cfg,
 					interface);

Source: Linux Commit 75e5b48

The patch adds proper validation by checking that the interface index is within bounds (interface >= MAX_CONFIG_INTERFACES) and that the interface pointer is not NULL (!os_desc_cfg->interface[interface]) before proceeding with the request processing.

Detection Methods for CVE-2022-25258

Indicators of Compromise

• Unexpected kernel panics or system crashes related to USB subsystem operations
• Kernel log entries showing NULL pointer dereferences in drivers/usb/gadget/composite.c
• Suspicious USB device connection events followed by system instability
• Crash dumps indicating memory corruption in the USB Gadget composite driver

Detection Strategies

• Monitor kernel logs (dmesg) for NULL pointer dereference errors originating from the USB Gadget subsystem
• Implement USB device monitoring to detect unusual or malformed USB descriptors and OS descriptor requests
• Deploy kernel-level intrusion detection to identify attempts to trigger the vulnerable code path
• Use SentinelOne's behavioral analysis to detect anomalous USB device interactions and kernel-level exploitation attempts

Monitoring Recommendations

• Enable comprehensive kernel logging for USB subsystem events with increased verbosity
• Configure alerts for kernel oops or panic events associated with the composite.c driver
• Implement physical security controls to limit unauthorized USB device connections to sensitive systems
• Utilize SentinelOne Singularity platform to monitor for kernel-level anomalies and potential exploitation attempts

How to Mitigate CVE-2022-25258

Immediate Actions Required

• Update the Linux kernel to version 5.16.10 or later immediately on all affected systems
• Apply vendor-specific patches from Debian, Fedora, and NetApp as applicable to your environment
• Restrict physical access to systems running vulnerable kernel versions until patches can be applied
• Consider disabling USB Gadget functionality if not required for system operation

Patch Information

The vulnerability has been addressed in Linux kernel version 5.16.10 and later. The fix adds proper bounds checking and NULL pointer validation before accessing the interface array. The patch is available via the Linux Kernel ChangeLog 5.16.10 and the specific commit can be reviewed at Linux Commit 75e5b48.

Distribution-specific patches are available through:

• Debian Security Advisory DSA-5092
• Debian Security Advisory DSA-5096
• Fedora Package Announcement
• NetApp Security Advisory NTAP-20221028-0007

Workarounds

• Implement physical security controls to prevent unauthorized USB device connections
• Disable USB Gadget functionality via kernel configuration if the feature is not required
• Use USB device whitelisting to restrict which devices can connect to the system
• Deploy endpoint detection and response (EDR) solutions like SentinelOne to detect exploitation attempts

# Check current kernel version
uname -r

# Verify if USB Gadget module is loaded
lsmod | grep gadget

# Disable USB Gadget module if not required (temporary)
sudo modprobe -r usb_f_fs
sudo modprobe -r libcomposite

# Block USB Gadget module from loading (persistent)
echo "blacklist libcomposite" | sudo tee /etc/modprobe.d/disable-usb-gadget.conf