CVE-2026-72406
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
net: sungem: fix probe error cleanup
gem_init_one() calls gem_remove_one() when register_netdev() fails. gem_remove_one() unregisters and frees resources owned by the net_device, including the DMA block, MMIO mapping, PCI regions, and the net_device itself. gem_init_one() then falls through to its own cleanup labels and frees the same resources again.
Keep the register_netdev() error path in gem_init_one(): clear drvdata so PM/remove paths do not see a half-registered device, remove the NAPI instance added during probe, and let the existing cleanup labels release the resources once.
The issue was found by a local static-analysis checker for probe error paths. The reported path was manually inspected before sending this fix.
Compile-tested with CONFIG_SUNGEM=y. Runtime testing was not performed because no sungem hardware is available.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the Linux kernel's sungem network driver implementation where improper resource cleanup occurs during device probe failure scenarios. The flaw manifests in the gem_init_one() function which attempts to register a network device through register_netdev() and subsequently calls gem_remove_one() when this registration fails. However, the current implementation contains a critical logical error where both functions attempt to free identical resources, leading to potential double-free conditions and memory corruption issues. The problematic behavior stems from the function falling through to its own cleanup labels after calling gem_remove_one(), causing redundant resource deallocation operations.
The technical root cause involves improper device state management during error recovery paths in the network driver's initialization sequence. When register_netdev() fails, the driver correctly identifies this failure condition and invokes gem_remove_one() to clean up resources that were partially allocated during the probe process. These resources include DMA blocks, MMIO mappings, PCI regions, and the net_device structure itself. However, the subsequent fall-through behavior means that the same cleanup labels execute again, attempting to deallocate memory regions that have already been freed by gem_remove_one(), creating a dangerous overlap in resource management operations.
This vulnerability represents a classic example of improper error handling in kernel space device drivers where cleanup routines are not properly isolated from normal execution paths. The issue falls under CWE-459 which describes "Incomplete Cleanup" and specifically relates to incomplete or incorrect resource deallocation during error conditions. From an operational perspective, this flaw could potentially allow attackers to exploit memory corruption vulnerabilities through carefully crafted network operations or device initialization sequences, though the attack surface is limited to systems with sungem hardware that may not be widely deployed.
The recommended mitigation strategy involves modifying the probe error path in gem_init_one() to properly handle device state cleanup without redundant resource deallocation. The fix requires clearing the driver data structure (drvdata) to prevent power management and removal paths from accessing a partially initialized device, removing the NAPI instance that was added during probe operations, and allowing the existing cleanup labels to execute once without interference from the initial error handling call. This approach ensures proper device state management while maintaining resource integrity throughout the initialization process.
The vulnerability was identified through automated static analysis tools specifically designed to detect problematic error handling patterns in device driver code, demonstrating the importance of systematic code review processes for kernel security. While compile-time testing with CONFIG_SUNGEM=y confirms the fix's syntactic correctness, the lack of runtime testing due to unavailable hardware limitations highlights the challenges in validating fixes for rare or deprecated hardware drivers. This issue aligns with ATT&CK technique T1547.006 which involves modifying system processes and device drivers to maintain persistence or enable privilege escalation through kernel-level modifications. The fix ensures that device driver error paths follow proper resource management protocols consistent with Linux kernel security best practices and maintains the integrity of the network subsystem's device initialization framework.