CVE-2026-68191 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath12k: fix NULL pointer dereference in rhash table destroy
When unbinding the ath12k driver, kernel NULL pointer dereferences occur in irq_work_sync() called from rhashtable_destroy().
Two hash tables are affected: 1. ath12k_link_sta hash table in ath12k_base 2. ath12k_dp_link_peer hash table in ath12k_dp
The issue happens because the destroy functions are called unconditionally in cleanup paths, but the hash tables are only initialized late in their respective init functions. If the device was never fully started or if the init functions failed before initializing the hash tables, the pointers will be NULL. The issues are always reproducible from a VM because the MSI addressing initialization is failing.
Call trace for ath12k_link_sta_rhash_tbl_destroy: RIP: irq_work_sync+0x1e/0x70 rhashtable_destroy+0x12/0x60 ath12k_link_sta_rhash_tbl_destroy+0x19/0x40 [ath12k]
ath12k_core_stop+0xe/0x80 [ath12k]
ath12k_core_hw_group_cleanup+0x6b/0xb0 [ath12k]
ath12k_pci_remove+0x60/0x110 [ath12k]
Call trace for ath12k_dp_link_peer_rhash_tbl_destroy: RIP: irq_work_sync+0x1e/0x70 rhashtable_destroy+0x12/0x60 ath12k_dp_link_peer_rhash_tbl_destroy+0x29/0x50 [ath12k]
ath12k_dp_cmn_device_deinit+0x21/0x140 [ath12k]
ath12k_core_hw_group_cleanup+0x6b/0xb0 [ath12k]
ath12k_pci_remove+0x60/0x110 [ath12k]
Fix this by adding NULL checks before calling rhashtable_destroy() in both destroy functions.
The NULL check approach was chosen because the rhashtable pointer serves as the initialization state indicator. The init can fail at various points, leaving some components uninitialized. Checking the pointer directly is simpler than adding separate state flags that would need synchronization.
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Analysis
by VulDB Data Team • 08/10/2026
This vulnerability represents a critical null pointer dereference in the linux kernel's ath12k wireless driver implementation that occurs during device unbinding operations. The flaw manifests when the driver attempts to clean up hash table resources through rhashtable_destroy() function calls without proper validation of whether these data structures were actually initialized. The vulnerability specifically affects two hash tables within the ath12k subsystem: ath12k_link_sta hash table located in ath12k_base and ath12k_dp_link_peer hash table situated in ath12k_dp component. Both tables are subject to destruction calls during driver cleanup phases even when their initialization processes have failed or were never completed successfully.
The root cause of this vulnerability stems from improper resource management within the driver's initialization and cleanup pathways. During normal operation, the hash tables are initialized late in their respective init functions, but the destroy functions execute unconditionally regardless of initialization status. When device initialization fails at early stages such as MSI addressing setup in virtual machine environments, the hash table pointers remain NULL while cleanup code attempts to process them. This condition creates a direct null pointer dereference scenario that results in kernel oops and potential system crashes. The vulnerability is particularly concerning because it can be reliably reproduced in virtualized environments where MSI initialization commonly fails, making it an attractive target for exploitation scenarios.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable denial-of-service attacks against wireless networking functionality. When triggered, the null pointer dereference causes kernel panics and system crashes that disrupt network connectivity for affected devices. This affects both physical and virtual deployments where the ath12k driver is utilized, particularly in environments where wireless infrastructure components depend on reliable driver behavior. The vulnerability affects systems running linux kernel versions containing this specific code path, with the potential for exploitation through crafted driver unbinding sequences or device removal operations that force cleanup functions to execute without proper initialization state validation.
The mitigation strategy implemented addresses the core issue by introducing explicit NULL pointer checks before invoking rhashtable_destroy() in both affected destroy functions. This approach aligns with established security practices for resource management and follows the principle of defensive programming where resources are validated before use. The solution leverages the fact that hash table pointers themselves serve as initialization indicators, eliminating the need for additional state tracking mechanisms that would require synchronization overhead. This fix pattern corresponds to common remediation techniques described in cwe-476 which addresses null pointer dereference vulnerabilities and aligns with attack mitigation strategies from the mitre att&ck framework under defensive technique categories related to privilege escalation and system stability maintenance. The implementation approach is minimal and focused, reducing attack surface while maintaining full backward compatibility with existing driver functionality and initialization sequences.