CVE-2026-63972 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
net: mana: Skip redundant detach on already-detached port
When mana_per_port_queue_reset_work_handler() runs after a previous detach succeeded but attach failed, the port is left in a detached state with apc->tx_qp and apc->rxqs already freed. Calling mana_detach() again unconditionally leads to NULL pointer dereferences during queue teardown.
Add an early exit in mana_detach() when the port is already in detached state (!netif_device_present) for non-close callers, making it safe to call idempotently. This allows the queue reset handler and other recovery paths to simply retry mana_attach() without redundant teardown.
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability exists within the Linux kernel's network driver implementation for Microsoft's Network Adapter (MANA) hardware. The issue manifests in a specific race condition scenario where the network port management logic fails to properly track the state of network interfaces during asynchronous operations. When the mana_per_port_queue_reset_work_handler function executes after a previous detach operation successfully completed but subsequent attach attempts failed, the system enters an inconsistent state where the port appears detached but underlying resources remain in an invalid configuration.
The core technical flaw occurs in the mana_detach() function which lacks proper state validation before attempting resource cleanup operations. When the function is called multiple times on already-detached ports, it attempts to access and free memory structures that have already been released during the previous detach operation. This leads to null pointer dereference conditions during queue teardown processes, causing system instability and potential denial of service scenarios. The vulnerability demonstrates characteristics consistent with CWE-476 Null Pointer Dereference, where a function fails to properly validate pointer references before accessing them.
The operational impact of this vulnerability extends beyond simple system crashes as it affects the reliability of network interface recovery mechanisms within the kernel's networking stack. Network administrators and system operators may experience unexpected disruptions when network interfaces attempt automatic recovery from transient errors, particularly in high-availability environments where rapid failover and recovery operations are essential. The improper resource management can lead to memory corruption patterns that might be exploited by malicious actors to compromise system integrity or cause persistent service interruptions.
The proposed mitigation strategy implements an idempotent design pattern for the mana_detach() function by adding early exit conditions when the port is already in a detached state, specifically checking for !netif_device_present flag. This approach aligns with ATT&CK technique T1490 Network Denial of Service by preventing resource exhaustion through invalid cleanup operations. The solution allows recovery paths to simply retry mana_attach() operations without unnecessary teardown steps, effectively creating a robust mechanism for handling asynchronous network state transitions. This defensive programming approach ensures that the driver can handle concurrent or overlapping operations gracefully while maintaining system stability and preventing cascading failures during network interface management operations.
The fix demonstrates proper adherence to kernel development best practices by implementing state-aware resource management and preventing redundant operations that could lead to system instability. The solution maintains backward compatibility while strengthening the driver's resilience against edge cases in asynchronous network management scenarios, particularly those involving rapid state transitions between attached and detached conditions. This type of vulnerability resolution is critical for maintaining the reliability of enterprise networking infrastructure where uninterrupted service availability is paramount for business continuity.