Bug 2481971 (CVE-2026-46100)

Summary: CVE-2026-46100 kernel: fs: afs: revert mmap_prepare() change
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's AFS (Andrew File System) component. The `mmap_prepare()` function was incorrectly used, leading to a reference count (refcount) leak. This issue occurs when `mmap_prepare()` establishes a refcount, but a subsequent operation fails, causing the refcount to be leaked. This resource leak could potentially lead to system instability or Denial of Service (DoS) over time.
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Description OSIDB Bzimport 2026-05-27 15:04:57 UTC
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.