CVE-2026-68198 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath6kl: fix use-after-free in aggr_reset_state()
The aggr_reset_state() function uses timer_delete() (non-synchronous) for the aggregation timer before proceeding to delete TID state and before the structure is freed by callers like aggr_module_destroy().
If the timer callback (aggr_timeout) is executing when aggr_reset_state() is called, the callback will continue to access aggr_conn fields like rx_tid[] and stat[] which may be freed immediately after by
kfree(aggr_info->aggr_conn) in aggr_module_destroy().
Additionally, the timer callback can re-arm itself via mod_timer() while aggr_reset_state() is running, creating a more complex race condition.
Use timer_delete_sync() instead to ensure any running timer callback has completed before returning.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability described represents a critical use-after-free condition within the ath6kl wireless driver of the Linux kernel, specifically affecting the aggregation state management functionality. This flaw exists in the aggr_reset_state() function which handles cleanup operations for wireless frame aggregation. The issue stems from improper synchronization mechanisms when dealing with timer callbacks and memory deallocation sequences. The vulnerability is classified under CWE-415 as an improper handling of memory allocation and deallocation, specifically manifesting as a use-after-free condition that can lead to arbitrary code execution or system instability.
The technical implementation flaw occurs when the aggr_reset_state() function invokes timer_delete() which is a non-synchronous operation for removing the aggregation timer. This asynchronous behavior creates a window of opportunity where the timer callback function aggr_timeout may still be executing while the containing data structures are being freed. The race condition becomes particularly dangerous because the timer callback continues to access fields within the freed memory structure, specifically the rx_tid[] and stat[] arrays located within the aggr_conn structure. When aggr_module_destroy() subsequently calls kfree(aggr_info->aggr_conn), it completely frees the memory that the timer callback is still attempting to reference, leading to potential memory corruption or exploitation opportunities.
This vulnerability directly impacts system stability and security by creating conditions where a malicious actor could potentially trigger the race condition through specific wireless frame patterns or timing sequences. The operational impact extends beyond simple system crashes to include potential privilege escalation and denial of service scenarios, as the corrupted memory state could be leveraged to execute arbitrary code within kernel space. The attack surface is primarily limited to systems utilizing the ath6kl wireless driver, which is commonly found in various embedded devices, routers, and IoT appliances running Linux-based operating systems. This aligns with ATT&CK technique T1068 which involves the exploitation of privilege escalation vulnerabilities through improper handling of system resources.
The mitigation strategy requires replacing the non-synchronous timer_delete() call with timer_delete_sync() to ensure complete synchronization before proceeding with memory deallocation operations. This change enforces proper ordering where any running timer callback must complete execution before the function returns, thereby eliminating the race condition window. The fix implements a fundamental principle of kernel security design that emphasizes proper resource management and synchronization primitives when dealing with concurrent access patterns. Organizations should prioritize applying this patch across all affected systems, particularly those in critical infrastructure environments where wireless connectivity is essential and system reliability paramount. The solution addresses the core issue identified in the Linux kernel's wireless subsystem by ensuring proper lifecycle management of timer-based operations within the aggregation module.