CVE-2026-89875 in Linux
Summary
by MITRE • 09/16/2026
In the Linux kernel, the following vulnerability has been resolved:
media: ti: vpe: quiesce overflow recovery before freeing streams
The VIP overflow recovery worker is armed from the hardirq handler when a FIFO overflow is detected, and the list-complete path looks the stream up through the VPDMA list private pointer. Both keep touching stream, port and device state; the recovery worker also resets the parser and VPDMA, repopulates the descriptor list, and re-enables the per-list IRQs.
vip_stop_streaming() masks and clears the per-list IRQs, but it neither synchronizes the hardirq handler nor disables recovery_work. An overflow IRQ that has already queued recovery_work, or a list-complete IRQ in flight when the stream is torn down, can therefore still dereference the stream after its resources are released: the descriptor list is freed by vip_release_stream() on file release, and the stream itself by free_stream() on unbind/remove.
Drain the recovery worker and the IRQ handler at both teardown points through a shared vip_quiesce_stream() helper, before any stream-owned resource is released. disable_work_sync() cancels pending recovery_work, drains a running instance, and raises its disable depth, so a subsequent schedule_work() issued by a racing IRQ handler is rejected at the workqueue scheduler: recovery_work cannot be requeued after disable_work_sync() takes effect. The worker may still re-enable the per-list IRQs before disable_work_sync() returns; disable_irqs() then masks those sources and synchronize_irq() waits for any in-flight handler that still dereferences stream state. In vip_stop_streaming() the helper runs before the parser is stopped, since a worker drained by disable_work_sync() may re-enable the parser before exiting and would otherwise undo the stop. recovery_work is created disabled and enabled in vip_start_streaming() before IRQs, pairing the enable with the teardown disable across the streaming lifecycle.
This issue was found by an in-house static analysis tool and confirmed by manual code review.
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified within the Linux kernel media subsystem for Texas Instruments VPE drivers represents a critical race condition involving stream resource management during tearing down operations. The core of the flaw lies in the asynchronous interaction between hardware interrupt handlers, specifically those triggered by FIFO overflows and list completions, and the synchronous cleanup routines executed when a video stream is stopped or released. When a FIFO overflow occurs, the hardirq handler arms an overflow recovery worker to handle the error state. This worker subsequently accesses shared data structures including streams, ports, and device states to reset parsers, repopulate descriptor lists, and re-enable interrupts. However, during the teardown process initiated by vip_stop_streaming or file release operations, the system masks and clears per-list IRQs but fails to synchronize with these asynchronous handlers or disable the recovery work item. This lack of synchronization creates a window where an overflow interrupt that has already queued its recovery task, or a list-complete interrupt currently in flight, can continue to execute after the stream resources have been freed by vip_release_stream or free_stream functions.
This race condition leads directly to use-after-free vulnerabilities and potential kernel panics due to dereferencing invalid memory addresses. The operational impact is severe as it allows an attacker who can trigger FIFO overflows through crafted media input streams to corrupt kernel memory, potentially leading to denial of service conditions or arbitrary code execution if the corrupted data structures are leveraged effectively. The issue stems from a failure in lifecycle management where the asynchronous recovery mechanisms remain active while their underlying dependencies are being dismantled. This is particularly dangerous because the descriptor list and stream objects are deallocated before ensuring that all pending work items have completed and no new ones can be scheduled, violating fundamental concurrency safety principles required for stable kernel operation.
To mitigate this vulnerability, a shared helper function named vip_quiesce_stream was introduced to enforce proper synchronization at both teardown points before any stream-owned resources are released. This mitigation strategy employs disable_work_sync which effectively cancels pending recovery work items and drains any running instance while raising its disable depth. By doing so, it ensures that subsequent schedule_work calls issued by racing IRQ handlers are rejected by the workqueue scheduler, preventing the requeuing of recovery tasks after quiescence begins. Furthermore, the implementation utilizes disable_irqs to mask interrupt sources and synchronize_irq to wait for any in-flight handler instances that might still reference stream state, thereby guaranteeing that no concurrent access occurs during resource deallocation. The parser is also stopped before draining the worker to prevent the worker from re-enabling it upon exit, which would otherwise undo the stop operation and reintroduce instability.
From a classification perspective, this vulnerability aligns with CWE-416 Use After Free, as the code attempts to access memory that has already been freed due to improper synchronization of asynchronous tasks. It also relates to CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization Race Condition, highlighting the failure to properly serialize access to shared data structures between interrupt contexts and process context teardown routines. In terms of ATT&CK mapping, this scenario reflects techniques associated with T1059 Command and Scripting Interpreter if exploited for execution, but more accurately maps to privilege escalation vectors where kernel memory corruption is leveraged to gain higher system privileges. The fix ensures that the recovery work is created in a disabled state during startup and only enabled after IRQs are set up, creating a symmetric enable-disable pattern across the streaming lifecycle that prevents such race conditions from occurring in future operations.