CVE-2026-43178
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Double mmput in Linux Kernel procfs

Publication date: 2026-05-06

Last updated on: 2026-05-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: procfs: fix possible double mmput() in do_procmap_query() When user provides incorrectly sized buffer for build ID for PROCMAP_QUERY we return with -ENAMETOOLONG error. After recent changes this condition happens later, after we unlocked mmap_lock/per-VMA lock and did mmput(), so original goto out is now wrong and will double-mmput() mm_struct. Fix by jumping further to clean up only vm_file and name_buf.
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Meta Information
Published
2026-05-06
Last Modified
2026-05-08
Generated
2026-06-16
AI Q&A
2026-05-06
EPSS Evaluated
2026-06-15
NVD
CVE-2026-43178
EUVD
EUVD-2026-27738
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel linux_kernel *
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Exploitability
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability exists in the Linux kernel's procfs subsystem, specifically in the function do_procmap_query(). When a user provides an incorrectly sized buffer for the build ID during a PROCMAP_QUERY, the system returns an -ENAMETOOLONG error. However, due to recent changes, this error occurs after unlocking certain locks and performing a memory management put operation (mmput()). The original error handling code then mistakenly performs a second mmput() on the same memory structure, causing a double mmput() issue. The fix involves adjusting the error handling to clean up only specific resources to avoid this double mmput().

Impact Analysis

The vulnerability can lead to a double mmput() call on a memory management structure, which may cause memory corruption or instability in the Linux kernel. This could potentially result in system crashes or unpredictable behavior, impacting system reliability and security.

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