CVE-2025-71236 Overview
A Null Pointer Dereference vulnerability has been identified in the Linux kernel's qla2xxx SCSI driver. The vulnerability exists in the qla_fab_async_scan function within the QLogic Fibre Channel HBA driver, where memory associated with a structure pointer (sp) is freed without proper validation, leading to a kernel NULL pointer dereference and subsequent system crash.
The vulnerability manifests during Fibre Channel fabric asynchronous scanning operations, particularly when handling RSCN (Registered State Change Notification) database changes and NVMe-FC controller connections. When the sp pointer is NULL at the time of memory deallocation, the kernel attempts to access an invalid memory address (0x00000000000000f8), triggering a page fault and system panic.
Critical Impact
This vulnerability can cause complete system crashes (kernel panic) on Linux systems using QLogic Fibre Channel HBAs, affecting enterprise storage connectivity and system availability.
Affected Products
- Linux kernel with qla2xxx SCSI driver module
- Systems using QLogic Fibre Channel Host Bus Adapters
- Enterprise environments with NVMe-FC storage configurations
Discovery Timeline
- 2026-02-18 - CVE CVE-2025-71236 published to NVD
- 2026-02-19 - Last updated in NVD database
Technical Details for CVE-2025-71236
Vulnerability Analysis
This vulnerability is a classic Null Pointer Dereference issue within the Linux kernel's qla2xxx driver, specifically in the qla_fab_async_scan.part.0 function. The crash occurs because the code attempts to access memory through a NULL pointer without performing adequate validation checks beforehand.
The crash signature reveals that the kernel tried to read from address 0x00000000000000f8, which represents an offset from a NULL base pointer. This indicates that a structure pointer was NULL when the code attempted to access one of its member fields at offset 0xf8. The affected code path handles asynchronous fabric scanning operations, which are triggered during Fibre Channel topology changes such as RSCN events.
The vulnerability was observed on Red Hat Enterprise Linux 9.5 (kernel 5.14.0-503.11.1.el9_5.x86_64) running on HPE Synergy 660 Gen10 hardware with QLogic HBAs, though the underlying issue affects the upstream qla2xxx driver code across multiple kernel versions.
Root Cause
The root cause is a missing NULL pointer validation before freeing memory associated with the sp (SCSI Request Packet) structure. In certain race conditions or error paths during fabric scanning operations, the sp pointer may be NULL when the code attempts to free associated memory resources. The fix involves adding a check to ensure sp is non-NULL before proceeding with memory deallocation operations.
Attack Vector
The attack vector for this vulnerability is primarily local, requiring conditions that trigger the vulnerable code path:
The vulnerability is triggered during Fibre Channel fabric topology changes, specifically when processing RSCN database change notifications. The crash occurs in the qla2xxx_2_dpc kernel thread (Deferred Procedure Call handler for the qla2xxx driver), which processes asynchronous events. While this is not a remotely exploitable vulnerability in the traditional sense, it could be triggered by network conditions or storage fabric events that cause RSCN notifications. An attacker with access to the Fibre Channel fabric could potentially induce topology changes that trigger this code path, leading to denial of service.
Detection Methods for CVE-2025-71236
Indicators of Compromise
- Kernel oops messages containing BUG: kernel NULL pointer dereference in system logs
- Call traces showing qla_fab_async_scan.part.0 in the stack backtrace
- System crashes occurring after RSCN database change notifications in qla2xxx driver logs
- Kdump crash files with RIP pointing to qla2xxx module functions
Detection Strategies
- Monitor /var/log/messages and dmesg output for qla2xxx-related kernel oops
- Configure kdump to capture kernel crash dumps for forensic analysis
- Use journalctl -k to review kernel messages for NULL pointer dereference events
- Implement automated log monitoring for patterns matching qla2xxx.*NULL pointer dereference
Monitoring Recommendations
- Enable kernel crash dump collection using kdump for post-mortem analysis
- Monitor system uptime and unexpected reboot events on affected systems
- Track Fibre Channel fabric events and RSCN notifications through HBA management tools
- Implement alerting on kernel oops patterns in centralized logging systems
How to Mitigate CVE-2025-71236
Immediate Actions Required
- Review systems running QLogic Fibre Channel HBAs for affected kernel versions
- Schedule maintenance windows to apply kernel updates containing the fix
- Enable kdump if not already configured to capture diagnostic information
- Monitor affected systems for crash events until patches are applied
Patch Information
Multiple kernel commits address this vulnerability by adding validation to check that sp is non-NULL before freeing associated memory. The fix has been backported to multiple stable kernel branches:
- Linux Kernel Commit 044131fce277
- Linux Kernel Commit 1a9585e4c58d
- Linux Kernel Commit 40ae93668226
- Linux Kernel Commit 85c0890fea6b
- Linux Kernel Commit 944378ead9a4
- Linux Kernel Commit 949010291bb9
- Linux Kernel Commit a46f81c1e627
Apply the appropriate kernel update from your distribution vendor that includes these fixes.
Workarounds
- Minimize fabric topology changes during production hours to reduce RSCN event frequency
- Consider temporarily disabling NVMe-FC if not critical and crashes are recurring
- Ensure redundant storage paths are configured to maintain connectivity if one HBA crashes
- Configure kdump and automatic reboot to minimize downtime from potential crashes
# Enable kdump for crash analysis
systemctl enable kdump
systemctl start kdump
# Verify kdump is configured correctly
kdumpctl status
# Check for kernel updates containing the fix
yum check-update kernel # RHEL/CentOS
apt list --upgradable | grep linux-image # Debian/Ubuntu
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
