CVE-2026-89796mm/damon/core: avoid infinite kdamond_merge_regions() internal loop
- —Not scoredno CVSS score yet
- 0.23%Exploitation in 30 daysEPSS · top 86% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: mm/damon/core: avoid infinite kdamond_merge_regions() internal loop Patch series "mm/damon: unurgent fixes for infinite loop, NULL de-ref and races", v1.1. Sashiko found a few issues in DAMON that could cause infinite loop, NULL dereference and monitoring results degradation. The first two sounds scary but the infinite loop happens only under unreasonable user setup. The NULL dereference is only in a unit test. Monitoring results degradation is trivial since it is only best-effort, and those happens from only unlikely races. Still those are bugs that better to fix if possible. Fix those. This patch (of 6): Due to online parameter update like events, the number of DAMON regions could be higher than the user-set upper limit. kdamond_merge_regions() repeats merge regions until the number meets the limit, while doubling the merge threshold up to the theoretical maximum threshold. It is tried only up to the theoretical maximum threshold because even the aggressive merging can fail from reducing the number of regions under the user-defined upper limit. For example, there could be many user-defined non-contiguous regions that cannot be merged. The threshold based loop break condition is evaluated by comparing the threshold for the next merging try against the theoretical maximum threshold. If max_thres is larger than UINT_MAX / 2, doubling the threshold could make it overflow, and bypass the loop break condition. In the case, if the number of regions cannot be reduced under the upper limit like explained above, the loop will run infinitely. Prevent the case by doing the break condition check before doubling the threshold. Also, prevent the threshold exceeding the maximum threshold, as it could overflow and apply the wrong merge threshold. This issue is unlikely to occur in real world, since having the max_thres higher than UINT_MAX / 2 require unrealistically large aggregation intervals compared to the sampling interval. Also, it requires an unrealistically large number of uncontiguous regions setup. Nonetheless, the consequence is bad and the fix is simple. The issue was discovered [1] by Sashiko.
Timeline
ID reserved
By Linux
- 5 days later
· 5 days later
Published
- 33 days later
· 33 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.23% · top 86% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 1e865019cef354a5f0314491b4b4fc9f9a613642 – < 407da1dd7f48e5ba22ceb8834f6923390632d025
- affected d7eda72e59bbf3ed592db7ff0fd8c246c73149a8 – < 65edd8b3a88278c9f8e5c7d8c15d4f296ce35078
- affected 11078e2d11465518a9e85096bd28f8cd5fa1ea41 – < 5b0953f86d65855dc901050f40bbe6da0475d198
- affected 310d6c15e9104c99d5d9d0ff8e5383a79da7d5e6 – < 769c16699c89811386eb003c8fd9dcb8d405b316
- affected 310d6c15e9104c99d5d9d0ff8e5383a79da7d5e6 – < 50a7a5aec1aa43efc297fd4377c1cbdc7d15620d
- affected 310d6c15e9104c99d5d9d0ff8e5383a79da7d5e6 – < 8a96a06e04d210845be5d9581c0e9e338947e8f8
- affected 310d6c15e9104c99d5d9d0ff8e5383a79da7d5e6 – < 123e4619ab6c8ab1c4cb1d7a58311a2af13929cd
- affected f2bd3184b6aeca6a497394b558337246e09fc02d
- affected 5.15.164 – < 5.15.222
- affected 6.1.101 – < 6.1.189
- affected 6.6.41 – < 6.6.158
- affected 6.9.10 – < 6.10
- affected 6.10
- unaffected < 6.10
- unaffected 5.15.222 – ≤ 5.15.*
- unaffected 6.1.189 – ≤ 6.1.*
- unaffected 6.6.158 – ≤ 6.6.*
- unaffected 6.12.111 – ≤ 6.12.*
- unaffected 6.18.53 – ≤ 6.18.*
- unaffected 7.2.5 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References7
- https://git.kernel.org/stable/c/407da1dd7f48e5ba22ceb8834f6923390632d025 (opens in a new tab)
- https://git.kernel.org/stable/c/65edd8b3a88278c9f8e5c7d8c15d4f296ce35078 (opens in a new tab)
- https://git.kernel.org/stable/c/5b0953f86d65855dc901050f40bbe6da0475d198 (opens in a new tab)
- https://git.kernel.org/stable/c/769c16699c89811386eb003c8fd9dcb8d405b316 (opens in a new tab)
- https://git.kernel.org/stable/c/50a7a5aec1aa43efc297fd4377c1cbdc7d15620d (opens in a new tab)
- https://git.kernel.org/stable/c/8a96a06e04d210845be5d9581c0e9e338947e8f8 (opens in a new tab)
- https://git.kernel.org/stable/c/123e4619ab6c8ab1c4cb1d7a58311a2af13929cd (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-80396 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-89796)Record last updated .