CVE-2026-68164 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/core: disallow overlapping input ranges for damon_set_regions()
damon_set_regions() assumes the input ranges are sorted by the address and don't overlap each other. Hence the assumption was initially to be explicitly validated. But commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting") has mistakenly removed the validation.
This can make DAMON behave in unexpected ways. At the best, the monitoring results snapshot will just look weird since there will be overlapping regions. DAMOS will also work weirdly, applying the same action multiple times for overlapping regions, and make DAMOS quota weird. More seriously, depending on the setup and regions updates sequence, negative size regions can be made. It will trigger WARN_ONCE() if the kernel is built with CONFIG_DAMON_DEBUG_SANITY=y. Depending on the monitoring results, the negative size region can further trigger division by zero in damon_merge_two_regions().
Note that some of the consequences including the WARN_ONCE() and the divide by zero depend on commits that were introduced after the root cause commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting").
Fix the problems by checking the assumption and returning an error if the input ranges don't meet the assumption.
The issue was discovered [1] by Sashiko.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability resides within the Linux kernel's DAMON (Dynamic Access Monitor) subsystem, specifically in the mm/damon/core module where the damon_set_regions() function processes memory region configurations. This function operates under a critical assumption that input memory ranges are both address-sorted and non-overlapping, which forms the foundation for proper memory monitoring operations within the kernel's memory management framework.
The technical flaw emerged from commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting") which inadvertently removed crucial validation mechanisms that previously ensured input ranges met the required sorting and non-overlapping conditions. This regression transformed a controlled operational environment into one where malformed memory region specifications could be processed without proper sanitization, creating multiple pathways for system instability.
The operational impact of this vulnerability manifests in several ways depending on how the DAMON subsystem processes the corrupted region data. At minimum, monitoring results become visually inconsistent due to overlapping regions appearing in snapshots, which fundamentally undermines the reliability of memory access patterns analysis that DAMON is designed to provide. More critically, DAMOS (DAMON's action system) begins executing actions multiple times on the same memory regions, leading to incorrect quota management and potentially skewed resource allocation decisions.
The most severe consequences occur when region updates create negative-sized memory regions through the mathematical operations involved in processing overlapping inputs. When the kernel is compiled with CONFIG_DAMON_DEBUG_SANITY=y, these invalid regions trigger WARN_ONCE() messages that indicate system instability, while in more extreme cases, division by zero errors can occur within damon_merge_two_regions() function when attempting to process these malformed negative-sized regions.
This vulnerability directly relates to CWE-129 and CWE-131 categories from the Common Weakness Enumeration framework, specifically addressing issues of insufficient input validation and improper handling of memory regions. The flaw also aligns with ATT&CK techniques related to privilege escalation through kernel vulnerabilities, as it could potentially be exploited to manipulate memory monitoring behavior for malicious purposes.
The fix implements explicit validation checks within damon_set_regions() that verify the sorting order and non-overlapping nature of input ranges before processing them, returning appropriate error codes when these assumptions are violated. This approach ensures that DAMON maintains its operational integrity while preventing the cascading failures that result from malformed region specifications. The solution addresses the root cause by restoring the validation logic that was inadvertently removed during the code reuse commit, thereby maintaining the expected behavior of the DAMON subsystem's memory monitoring capabilities.
References to industry standards demonstrate how this vulnerability represents a classic case of input sanitization failure that could compromise system stability. The fix aligns with secure coding practices that emphasize defensive programming and explicit validation of assumptions within kernel subsystems. This remediation ensures that DAMON's memory region management maintains the mathematical consistency required for reliable memory access monitoring operations while preventing potential denial-of-service conditions through invalid memory region specifications.