CVE-2026-98650
Received Received - Intake

Race Condition in Linux Kernel KVM s390 Dat Skey Functions

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix potential races in dat skey functions When dat_cond_set_storage_key() finds a large page, it will conditionally set the storage key in absolute memory using large_crste_to_phys() to get the absolute address. There is a race window between dat_entry_walk() and large_crste_to_phys(): the large page could have been split concurrently, and large_crste_to_phys() might be called with a crste that does not designate a large page, leading to crashes. Similar issues were also present in dat_set_storage_key(). dat_get_storage_key() and dat_reset_reference_bit() did instead check for a potential concurrent splitting of the large page, but then handled it incorrectly. Fix by performing a READ_ONCE on the crste pointer, checking and using the result, instead of dereferencing the pointer again. In case a race is detacted, try dat_entry_walk() again.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98650
EUVD
EUVD-2026-103564

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
Linux Linux 8e03e8316eb242af307d1c789d09f1a1457cf9a3
Linux Linux 8e03e8316eb242af307d1c789d09f1a1457cf9a3
Linux Linux 7.0

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a race condition vulnerability in the Linux kernel's KVM for s390 architecture. It involves improper handling of storage key operations on large pages, where concurrent page splitting can lead to crashes due to incorrect memory address calculations.

Detection Guidance

This vulnerability is specific to the Linux kernel's KVM s390 implementation and involves race conditions in storage key functions. Detection requires checking kernel logs for crashes or errors related to KVM s390 operations, particularly during large page handling. Commands like dmesg | grep -i kvm or journalctl -k | grep -i kvm may help identify issues. Ensure your kernel version is up-to-date to verify if the fix is applied.

Impact Analysis

If exploited, this could cause system crashes or instability on systems running vulnerable Linux kernel versions with KVM enabled for s390. It may lead to denial-of-service conditions but does not appear to allow privilege escalation or data theft.

Mitigation Strategies

Apply the latest kernel update from your Linux distribution to ensure the fix for this vulnerability is installed. If immediate patching is not possible, consider disabling KVM s390 virtualization on affected systems as a temporary workaround. Monitor kernel logs for crashes or errors related to KVM s390 operations.

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