Revert mmap_prepare() Change in Linux Kernel

Publication date: 2026-05-27

Last updated on: 2026-06-25

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: fs: afs: revert mmap_prepare() change Partially reverts commit 9d5403b1036c ("fs: convert most other generic_file_*mmap() users to .mmap_prepare()"). This is because the .mmap invocation establishes a refcount, but .mmap_prepare is called at a point where a merge or an allocation failure might happen after the call, which would leak the refcount increment. Functionality is being added to permit the use of .mmap_prepare in this case, but in the interim, we need to fix this.

CVSS Scores

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Meta Information

Published

2026-05-27

Last Modified

2026-06-25

Generated

2026-07-07

AI Q&A

2026-05-27

EPSS Evaluated

2026-07-05

NVD

CVE-2026-46100

EUVD

EUVD-2026-32483

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	From 6.19 (inc) to 7.0.4 (exc)
linux	linux_kernel	From 6.17 (inc) to 6.18.27 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability exists in the Linux kernel's AFS filesystem code related to memory mapping operations. Specifically, a change to the mmap_prepare() function was partially reverted because the original change caused a reference count leak. The issue arises because the .mmap function establishes a reference count, but .mmap_prepare is called earlier where a merge or allocation failure might occur after the call, leading to the reference count increment being leaked. The fix involves reverting the problematic change and adding functionality to safely use .mmap_prepare in this context.

Impact Analysis

The vulnerability can lead to a reference count leak in the Linux kernel's AFS filesystem memory mapping operations. This leak could potentially cause resource exhaustion or instability in the kernel due to unreleased references, which might degrade system performance or cause unexpected behavior.

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