CVE-2025-37787 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: mv88e6xxx: avoid unregistering devlink regions which were never registered
Russell King reports that a system with mv88e6xxx dereferences a NULL pointer when unbinding this driver: https://lore.kernel.org/netdev/[email protected]/
The crash seems to be in devlink_region_destroy(), which is not NULL tolerant but is given a NULL devlink global region pointer.
At least on some chips, some devlink regions are conditionally registered since the blamed commit, see mv88e6xxx_setup_devlink_regions_global():
if (cond && !cond(chip)) continue;
These are MV88E6XXX_REGION_STU and MV88E6XXX_REGION_PVT. If the chip does not have an STU or PVT, it should crash like this.
To fix the issue, avoid unregistering those regions which are NULL, i.e. were skipped at mv88e6xxx_setup_devlink_regions_global() time.
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Analysis
by VulDB Data Team • 03/16/2026
The vulnerability CVE-2025-37787 represents a critical null pointer dereference issue within the Linux kernel's dsa subsystem, specifically affecting the mv88e6xxx driver used for Marvell 88e6xxx switch chips. This flaw manifests during driver unbinding operations when the system attempts to unregister device link regions that were never actually registered due to conditional logic in the setup process. The issue stems from a fundamental mismatch between region registration and unregistration logic, where the driver fails to properly account for regions that are skipped during initialization based on chip-specific conditions.
The technical implementation flaw occurs in the devlink_region_destroy() function which does not perform null pointer validation before attempting to operate on device link regions. When the mv88e6xxx driver unbinds from a switch chip, it calls devlink_region_destroy() on regions that were conditionally skipped during the setup phase, specifically MV88E6XXX_REGION_STU and MV88E6XXX_REGION_PVT. The conditional registration logic in mv88e6xxx_setup_devlink_regions_global() explicitly skips registration of these regions when specific chip conditions are not met, yet the unregistration process does not account for this possibility. This creates a scenario where the driver attempts to destroy NULL pointers, leading to immediate system crashes and potential denial of service conditions.
From an operational perspective, this vulnerability affects systems utilizing Marvell 88e6xxx switch chips in networking infrastructure, particularly those implementing the dsa (Distributed Switch Architecture) framework. The impact extends beyond simple system crashes to potentially compromise network connectivity and system stability in environments where these switches are critical components. The vulnerability is particularly concerning because it occurs during driver unbinding operations, which can happen during system shutdown, hot-plug events, or when administrators attempt to reload or remove the driver module. This creates a window of opportunity for attackers to trigger denial of service conditions or potentially escalate privileges through carefully crafted system operations.
The root cause aligns with CWE-476 Null Pointer Dereference, a well-documented weakness in software development practices where programs fail to check for null pointers before dereferencing them. This vulnerability also maps to ATT&CK technique T1499.004 for Network Denial of Service, as it can be exploited to disrupt network services through system crashes. The fix implemented addresses the issue by modifying the driver's unregistration logic to check whether device link regions were actually registered before attempting to unregister them, thereby preventing the null pointer dereference that leads to system crashes. This defensive programming approach ensures that the driver maintains proper state management between registration and unregistration phases, preventing resource management errors that could be exploited in malicious scenarios. The solution demonstrates proper error handling and state validation practices that should be implemented across similar device driver frameworks to prevent similar vulnerabilities in the broader networking subsystem.