CVE-2026-68332 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
net: airoha: Fix potential use-after-free in airoha_ppe_deinit()
airoha_ppe_deinit() replaces the NPU pointer with NULL via rcu_replace_pointer() but does not wait for existing RCU readers to exit before calling ppe_deinit() and airoha_npu_put(). This can cause a use-after-free if a reader in an RCU read-side critical section still holds a reference to the NPU when it is freed.
The init path (airoha_ppe_init) already calls synchronize_rcu() after rcu_assign_pointer(), but the deinit path introduced in commit 6abcf751bc08 ("net: airoha: Fix schedule while atomic in airoha_ppe_deinit()") omitted the matching barrier when switching from rcu_read_lock()/rcu_dereference() to rcu_replace_pointer().
Add synchronize_rcu() before ppe_deinit() to ensure all existing RCU readers have completed before the NPU resources are released.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability resides within the Linux kernel's airoha network driver implementation, specifically in the deinitialization function airoha_ppe_deinit(). This function manages the cleanup of network processing engine resources associated with the Airoha wireless communication hardware. The flaw manifests as a potential use-after-free condition that can lead to system instability and arbitrary code execution. The issue stems from improper handling of RCU (Read-Copy-Update) synchronization mechanisms during resource deallocation, creating a temporal window where freed memory can still be accessed by concurrent readers.
The technical implementation flaw occurs when airoha_ppe_deinit() employs rcu_replace_pointer() to replace the NPU pointer with NULL, but fails to ensure that all active RCU read-side critical sections have completed before proceeding with resource deallocation. While the initialization path correctly implements synchronize_rcu() after rcu_assign_pointer(), the deinitialization logic introduced in commit 6abcf751bc08 neglected to add the corresponding synchronization barrier when transitioning from traditional rcu_read_lock()/rcu_dereference() patterns to the newer rcu_replace_pointer() approach. This asymmetry creates a race condition where readers that were active before the pointer replacement may still hold references to memory that gets freed immediately afterward.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling privilege escalation and system compromise within the kernel space. Attackers could exploit this use-after-free condition by carefully orchestrating concurrent access patterns that maintain references to the NPU structure while it is being deallocated, leading to memory corruption that might be leveraged for arbitrary code execution. The vulnerability affects systems utilizing Airoha wireless networking hardware and represents a critical security risk in kernel-level drivers, particularly in environments where network processing occurs under high concurrency.
Mitigation strategies must focus on ensuring proper RCU synchronization during resource deallocation operations. The recommended fix involves adding synchronize_rcu() call immediately before ppe_deinit() and airoha_npu_put() function calls to guarantee that all existing RCU readers have completed their critical sections before memory deallocation proceeds. This approach aligns with established kernel security practices and follows the principle of least privilege by preventing concurrent access to freed resources. Additionally, developers should implement comprehensive testing procedures that include race condition detection and memory safety verification to prevent similar issues in future driver implementations.
This vulnerability maps directly to CWE-416 Use After Free, which specifically addresses the use of memory after it has been freed, and also relates to CWE-362 Concurrent Execution Using Shared Resource with Unprotected Read-Write Access. From an ATT&CK perspective, this represents a privilege escalation vector through kernel exploitation techniques, potentially enabling an attacker to gain elevated system privileges. The vulnerability demonstrates how seemingly minor synchronization gaps in kernel code can create significant security risks, emphasizing the critical importance of proper RCU implementation and thorough testing of concurrent access patterns in kernel space drivers.