CVE-2026-64358 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
media: mtk-jpeg: cancel workqueue on release for supported platforms only
Since a recent fix the mtk_jpeg_release function cancels any pending or running work present in the driver workqueue using cancel_work_sync function. Currently, only the multicore based variants use this workqueue and they have the jpeg_worker platform data field initialized with a workqueue callback function. For the others, this field value remain NULL by default. The cancel_work_sync function is unconditionally called in mtk_jpeg_release function, even for the variants that do not use the workqueue. This call generates a WARN_ON print in __flush_work because the workqueue callback function presence check fails in __flush_work function (used by cancel_work_sync).
So, to avoid these warnings, call cancel_work_sync only if a workqueue callback is defined in platform data.
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Analysis
by VulDB Data Team • 07/25/2026
The vulnerability in question affects the Linux kernel's multimedia subsystem, specifically within the mtk-jpeg driver that handles JPEG encoding and decoding operations for MediaTek SoC platforms. This issue stems from an improper implementation of resource cleanup procedures during driver release operations, creating a potential system instability through unnecessary warning messages and potentially problematic behavior when dealing with different hardware variants.
The technical flaw manifests in the mtk_jpeg_release function where the cancel_work_sync mechanism is invoked unconditionally regardless of whether the specific platform variant actually utilizes the workqueue infrastructure. This driver supports multiple MediaTek JPEG hardware configurations including both single-core and multi-core variants, each with distinct resource management requirements. The multi-core platforms properly initialize the jpeg_worker field in platform data with valid workqueue callback functions, while single-core variants leave this field as NULL by default.
When cancel_work_sync is called on platforms where no workqueue callback function exists, the underlying __flush_work function triggers a WARN_ON condition because it performs an internal check for callback function presence that fails when the jpeg_worker field remains NULL. This generates kernel warning messages that can clutter system logs and potentially indicate improper resource management to administrators monitoring system health. The issue represents a design inconsistency where the driver assumes all variants require identical cleanup procedures despite their differing hardware capabilities and resource utilization patterns.
This vulnerability impacts system stability through excessive warning generation and represents a deviation from proper kernel driver development practices. According to CWE-691, this scenario describes an insufficient control flow management issue where the code path fails to properly account for conditional platform-specific behavior. The problem also aligns with ATT&CK technique T1484.001 which involves privilege escalation through system modification, as improper cleanup operations can lead to resource leaks or unstable system states that might be exploited by malicious actors.
The recommended mitigation involves implementing conditional logic in the mtk_jpeg_release function that checks for the presence of workqueue callback functions before invoking cancel_work_sync. This approach ensures that only platforms requiring workqueue cleanup operations actually perform these operations, preventing unnecessary warnings while maintaining proper resource management for all supported hardware variants. The fix aligns with kernel development best practices by ensuring that driver cleanup procedures are platform-specific and avoid generic operations that may not be applicable to all device configurations.