CVE-2026-90316 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/omap: dsi: Do not copy isr table
To be able to unregister stuff from isrs, the corresponding table was copied. Nobody seems to unregister stuff that way, so it does not help. But there are stack-allocated objects passed to these isrs giving chances of UAF of these objects if irqs are unregistered while they are handled, so better do not copy that table.
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel driver for the OMAP Display Subsystem contains a critical flaw within its DSI (Display Serial Interface) interrupt handling mechanism. The vulnerability stems from an implementation decision to create a local copy of the Interrupt Service Routine (ISR) handler table during initialization or configuration phases. This design choice was originally intended to facilitate the unregistration and cleanup of specific interrupt handlers, allowing for dynamic management of hardware interrupts without affecting global state immediately. However, this approach introduces significant memory safety risks because it decouples the runtime execution context from the original data structures managed by the driver core.
The primary technical flaw involves a Use-After-Free (UAF) condition triggered during race conditions between interrupt registration and unregistration processes. When an ISR is registered, it often relies on stack-allocated objects or temporary kernel memory contexts to process hardware events efficiently. By copying the handler table rather than maintaining direct references to the original structures, the driver creates a scenario where the copied handlers may point to memory locations that are no longer valid if the associated interrupt source is unregistered while an interrupt event is actively being processed. If the system attempts to unregister these interrupts while they are still pending or in-flight, the stack-allocated objects referenced by the ISR logic can be freed prematurely. Subsequent execution of the copied handler then accesses this deallocated memory, leading to undefined behavior, potential kernel panics, or arbitrary code execution depending on how the freed memory is reused.
From a security perspective, this vulnerability aligns with CWE-416, Use After Free, which describes situations where software continues to use a pointer after it has been freed. This can lead to crashes, data corruption, and privilege escalation. In the context of modern threat modeling, such race conditions in kernel interrupt handlers are often associated with ATT&CK technique T1059, Command and Scripting Interpreter, if an attacker can leverage the memory corruption to execute arbitrary code within the kernel space. The impact is severe because it affects a core subsystem responsible for display output on OMAP-based hardware, potentially allowing local attackers with sufficient privileges to escalate their rights or cause denial of service by triggering specific timing conditions during device configuration changes.
The operational impact includes system instability and potential compromise of host integrity. An attacker who can control the sequence of DSI interface initialization and deinitialization could exploit this race condition to corrupt kernel memory structures. This corruption might allow for information disclosure, allowing access to sensitive data residing in adjacent memory pages, or privilege escalation by overwriting critical function pointers within the kernel's interrupt handling infrastructure. Given that display drivers often run with high privileges due to their direct hardware interaction capabilities, successful exploitation could provide a foothold for further lateral movement within an embedded system or mobile device environment.
To mitigate this vulnerability, the recommended course of action is to remove the copying logic from the DSI driver and instead maintain direct references to the original interrupt handler table. This ensures that when interrupts are unregistered, the handlers operate on stable memory contexts that remain valid for their intended lifecycle. Developers should ensure proper synchronization mechanisms, such as mutexes or spinlocks, are employed around interrupt registration and unregistration sequences to prevent race conditions. Additionally, implementing strict lifetime management for stack-allocated objects used in ISR contexts is essential. System administrators should apply the latest kernel patches provided by their distribution vendors, which include this fix, to eliminate the risk of memory corruption associated with dynamic IRQ handling in OMAP display drivers. Regular auditing of interrupt handler implementations against CWE standards can help prevent similar issues in other subsystems.