CVE-2026-90290 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
arm64: hibernate: Restore DAIF state on error
Sashiko AI has reported that if swsusp_mte_save_tags() for some reason fails we return from swsusp_arch_suspend() with DAIF being masked - that is not what we'd expect. Restore the saved DAIF state before returning from the error path.
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel's hibernation subsystem, specifically within the arm64 architecture implementation, contained a critical control flow flaw in its error handling logic during system suspend operations. The vulnerability centers on the swsusp_arch_suspend function, which is responsible for managing the state of processor registers and interrupt masks when transitioning the system into a suspended or hibernated state. During this process, the kernel saves various architectural states to ensure that upon resumption, the CPU returns to an operational condition identical to its pre-suspend status. A specific component of this state management involves the DAIF register, which controls the masking of Debug, Abort, FIQ (Fast Interrupt Request), and IRQ (Interrupt Request) signals on ARM64 processors. Proper preservation and restoration of these interrupt masks are essential for maintaining system stability and security boundaries during power state transitions.
The identified flaw occurs when the swsusp_mte_save_tags function fails to execute successfully. This function is tasked with saving Memory Tagging Extension tags, a feature used in modern ARM architectures to detect memory safety violations such as buffer overflows or use-after-free errors by attaching metadata pointers to heap allocations. If this specific save operation encounters an error and returns a failure code, the existing implementation incorrectly proceeds to return from swsusp_arch_suspend without restoring the previously saved DAIF state. Consequently, the CPU exits the suspend routine with its interrupt masks in an altered state, typically resulting in all interrupts being masked or disabled. This deviation from expected behavior means that upon resumption, the system may fail to respond to hardware interrupts, software timers, and other critical asynchronous events required for normal operation.
The operational impact of this vulnerability is severe, primarily manifesting as a denial of service condition following an attempted hibernation cycle. When the system resumes from hibernate after encountering this error path, it becomes effectively unresponsive because the processor cannot process incoming interrupts. This renders the device unusable until a hard reset or power cycle is performed to reinitialize the hardware state. For systems relying on reliable hibernation capabilities for energy conservation or rapid resume functionality, such as mobile devices and embedded systems running Linux kernel variants, this flaw can lead to significant availability issues. Furthermore, while the primary impact is functional instability rather than direct privilege escalation, an unresponsive system creates a window where security monitoring agents may fail to operate correctly due to their reliance on timer interrupts for periodic checks or heartbeat signals.
From a vulnerability classification perspective, this issue aligns with CWE-391, Unchecked Error Condition, as the code path fails to properly handle the error return value by neglecting necessary cleanup operations before exiting the function. It also relates to CWE-456, Missing Initialization of Critical Variable, in the context that the critical DAIF state is not restored to its expected baseline after a failure. In terms of adversary behavior mapping under the MITRE ATT&CK framework, this vulnerability does not directly facilitate initial access or privilege escalation but could be leveraged within an Availability impact category if an attacker can trigger the specific error condition in swsusp_mte_save_tags repeatedly. However, given that MTE tag saving is typically a kernel-internal operation triggered by standard hibernation procedures rather than user-space input, exploitation would likely require physical access or prior code execution privileges to manipulate memory states leading to this failure path.
Mitigation for this vulnerability requires applying the upstream Linux kernel patch that corrects the error handling logic in swsusp_arch_suspend. The fix ensures that regardless of whether swsusp_mte_save_tags succeeds or fails, the saved DAIF state is explicitly restored before returning from the function. System administrators and developers should update their kernels to versions where this specific arm64 hibernation patch has been merged into the stable release branches. Additionally, organizations deploying ARM-based infrastructure with hibernation capabilities enabled should verify that kernel updates are applied promptly during maintenance windows. Testing hibernate-resume cycles in staging environments after applying patches can help confirm that interrupt handling resumes correctly and that no residual state corruption persists across power transitions.