CVE-2025-71222: Linux Kernel Buffer Overflow Vulnerability

CVE-2025-71222 Overview

A vulnerability has been identified in the Linux kernel's wlcore WiFi driver that can lead to kernel panic conditions. The issue occurs in the wl1271_tx_work function where insufficient socket buffer (skb) headroom validation before calling skb_push can trigger an skb_under_panic Oops. This memory safety issue arises when the available headroom is less than required, typically presenting as a 16-byte shortfall (110 - 94 = 16 bytes).

Critical Impact

Systems using the wlcore WiFi driver (commonly found in TI WiLink wireless chipsets) may experience kernel panics and system crashes during WiFi transmission operations, resulting in denial of service conditions.

Affected Products

• Linux kernel with wlcore WiFi driver enabled
• Systems using TI WiLink wireless chipsets (WL12xx/WL18xx series)
• Linux kernel versions prior to the security patches

Discovery Timeline

• 2026-02-14 - CVE CVE-2025-71222 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2025-71222

Vulnerability Analysis

This vulnerability is classified as a memory corruption issue, specifically an Out-of-Bounds Write condition that manifests as an skb underflow. The Linux kernel's socket buffer (skb) data structure maintains a headroom area before the actual packet data to allow for prepending headers during network packet processing. The wlcore driver's transmit path (wl1271_tx_work) calls skb_push to add protocol headers to outgoing WiFi frames without first ensuring adequate headroom exists.

When skb_push is called with insufficient headroom, the kernel triggers the skb_under_panic function, resulting in an immediate kernel panic. This defensive measure prevents potential memory corruption that would occur if the operation were allowed to proceed, writing data into memory regions preceding the allocated buffer space.

Root Cause

The root cause of this vulnerability is missing validation of socket buffer headroom in the wl1271_tx_work transmit function of the wlcore driver. The driver assumes that incoming skbs will always have sufficient headroom (typically 110 bytes) to accommodate WiFi frame headers, but under certain conditions, skbs arrive with only 94 bytes of headroom available. This 16-byte shortfall triggers the panic condition when the driver attempts to prepend header data.

The fix ensures that skb_headroom is checked before any skb_push operation, and if insufficient space exists, the buffer is reallocated with adequate headroom using skb_realloc_headroom or similar kernel APIs.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to have access to a system with the affected wlcore WiFi driver loaded. Exploitation does not require special privileges but does depend on triggering specific network transmission conditions that result in skbs with reduced headroom being passed to the transmit path.

The vulnerability is triggered during normal WiFi transmission operations when socket buffers with insufficient headroom enter the wl1271_tx_work function. While this typically occurs due to edge cases in the kernel's network stack rather than direct attacker manipulation, it can potentially be triggered by crafted network traffic patterns or specific driver configurations.

Detection Methods for CVE-2025-71222

Indicators of Compromise

• Kernel panic messages referencing skb_under_panic in system logs
• Crash dumps indicating failures in wl1271_tx_work or related wlcore driver functions
• Unexpected system reboots on devices with TI WiLink wireless chipsets
• Kernel oops messages mentioning the wlcore or wl12xx/wl18xx modules

Detection Strategies

• Monitor kernel logs (dmesg, /var/log/kern.log) for skb_under_panic or wlcore-related crash messages
• Deploy kernel crash dump analysis tools (kdump, crash) to identify affected systems
• Use SentinelOne's kernel-level monitoring to detect anomalous wlcore driver behavior
• Implement automated log analysis for patterns matching wlcore driver failures

Monitoring Recommendations

• Enable kernel crash dumping (kdump) to capture diagnostic information when panics occur
• Configure centralized log collection to aggregate kernel messages from affected endpoints
• Monitor system uptime and unexpected reboot patterns on devices using wlcore WiFi
• Deploy endpoint detection solutions capable of correlating kernel panic events with driver activity

How to Mitigate CVE-2025-71222

Immediate Actions Required

• Update the Linux kernel to a version containing the security patches
• If unable to patch immediately, consider disabling or unloading the wlcore driver module if WiFi functionality is not required
• Monitor affected systems for signs of instability or unexpected reboots
• Review system logs for any existing occurrences of the vulnerability being triggered

Patch Information

The Linux kernel maintainers have released patches to address this vulnerability across multiple stable kernel branches. The fix ensures proper skb headroom validation before any skb_push operations in the wlcore driver's transmit path. Patches are available through the following kernel commits:

• Linux Kernel Commit 689a7980
• Linux Kernel Commit 71de0b6e
• Linux Kernel Commit 745a0810
• Linux Kernel Commit 88295a55
• Linux Kernel Commit b1673123
• Linux Kernel Commit cd89a465
• Linux Kernel Commit e75665dd

Workarounds

• Unload the wlcore driver module if WiFi is not required: modprobe -r wlcore_sdio wl18xx wl12xx wlcore
• Use alternative WiFi hardware with a different driver if available
• Implement network restrictions to reduce WiFi transmission activity on affected systems
• Consider using wired Ethernet connectivity as a temporary alternative

# Temporary workaround: Disable wlcore driver
# Check if wlcore modules are loaded
lsmod | grep wlcore

# Unload wlcore driver modules (if WiFi not needed)
sudo modprobe -r wlcore_sdio wl18xx wl12xx wlcore

# Prevent wlcore from loading on boot (temporary measure)
echo "blacklist wlcore" | sudo tee /etc/modprobe.d/blacklist-wlcore.conf
echo "blacklist wl18xx" | sudo tee -a /etc/modprobe.d/blacklist-wlcore.conf
echo "blacklist wl12xx" | sudo tee -a /etc/modprobe.d/blacklist-wlcore.conf