CVE-2026-74514
Received Received - Intake

KVM: s390 PCI Memory Accounting Use-After-Free

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: pci: Fix memory accounting for pinned/unpinned pages The account_mem() and unaccount_mem() functions call get_uid() which increments the reference count of struct user_struct on every invocation. But we don't decrement the count by calling free_uid(). It also accounted/unaccounted the pages against the current->mm. But its possible the unaccount_mem() can be called from a different process context than the one that originally pinned the pages. Let's fix this by storing the pinning process user_struct and mm_struct when accounting for pinned pages, and subsequently free these resources when the pages are unpinned. [borntraeger@linux.ibm.com: Fixed whitespace]

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-74514
EUVD
EUVD-2026-59707

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves incorrect memory accounting for pinned/unpinned pages in the KVM s390 PCI subsystem. The functions account_mem() and unaccount_mem() increment the reference count of user_struct via get_uid() but fail to decrement it with free_uid(). Additionally, memory is accounted against the current process's mm_struct, which may differ from the process that originally pinned the pages.

Detection Guidance

This vulnerability is specific to the Linux kernel's KVM s390 PCI memory accounting. Detection requires checking kernel logs for memory accounting errors or examining the KVM s390 PCI module for unaccounted memory leaks. Use commands like dmesg | grep -i 'account_mem' or journalctl -k | grep -i 'memory accounting' to identify issues.

Impact Analysis

This vulnerability could lead to memory leaks or incorrect memory usage tracking, potentially causing system instability or resource exhaustion. It may also allow unauthorized memory access if exploited, though exploitation would require specific conditions and privileges.

Mitigation Strategies

Apply the kernel patch that fixes the memory accounting issue in KVM s390 PCI. Update to a patched kernel version where the account_mem() and unaccount_mem() functions properly decrement user_struct references. Reboot the system after applying the patch.

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