CVE-2026-46065
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Deferred I/O Use-After-Free in Linux Kernel

Publication date: 2026-05-27

Last updated on: 2026-05-30

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an instance as part of initializing deferred I/O and remove it only after the final mapping has been closed. If the fb_info and the contained deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info to invalidate the mapping. Any access will then result in a SIGBUS signal. Fixes a long-standing problem, where a device hot-unplug happens while user space still has an active mapping of the graphics memory. The hot- unplug frees the instance of struct fb_info. Accessing the memory will operate on undefined state.
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Meta Information
Published
2026-05-27
Last Modified
2026-05-30
Generated
2026-06-16
AI Q&A
2026-05-27
EPSS Evaluated
2026-06-15
NVD
CVE-2026-46065
EUVD
EUVD-2026-32447
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
linux linux_kernel *
linux linux_kernel to 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (inc)
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Exploitability
CWE
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability exists in the Linux kernel's framebuffer device (fbdev) deferred I/O subsystem. It involves improper handling of the lifetime of the struct fb_info, which represents the framebuffer device information.

Specifically, when a device is hot-unplugged while user space still has an active memory mapping of the graphics memory, the struct fb_info instance is freed. However, user space may still access this memory, which leads to undefined behavior.

The fix involves holding the state of deferred I/O in a separate struct fb_deferred_io_state, allocating it during initialization, and only removing it after the final mapping is closed. If fb_info is freed earlier, the mapping is invalidated so that any access results in a SIGBUS signal, preventing undefined memory access.

Impact Analysis

This vulnerability can lead to undefined behavior or system instability if a device is hot-unplugged while user space still accesses the graphics memory mapping.

Specifically, accessing freed memory can cause crashes or data corruption in applications using the framebuffer device.

The fix ensures that such access results in a SIGBUS signal, which safely notifies the application of invalid memory access instead of causing unpredictable behavior.

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