Medium [CVE-2026-68164] Linux kernel: Division by zero in DAMON due to missing input validation in damon_set_regions
This medium-severity Red Hat Linux advisory covers CVE-2026-68164.
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Summary
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(). 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. A flaw was found in the Linux kernel's DAMON (Data Access MONitor) subsystem.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
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