GHSA-FHQC-6XWP-7X74
Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31In the Linux kernel, the following vulnerability has been resolved:
mm/damon/ops-common: handle extreme intervals in damon_hot_score()
Fix three issues in damon_hot_score() that comes from wrong handling of extreme (zero or too high) monitoring intervals user setup.
When the user sets sampling interval zero, damon_max_nr_accesses(), which is called from damon_hot_score(), causes a divide-by-zero. Needless to say, it is a problem.
When the user sets the aggregation interval zero, the function returns zero. It is wrong, since the real maximum nr_acceses in the setup should be one. Worse yet, it can cause another divide-by-zero from its caller, damon_hot_score(), since it uses damon_max_nr_accesses() return value as a denominator.
When the user sets the aggregation interval very high, damon_hot_score() could return a value out of [0, DAMOS_MAX_SCORE] range. Since the return value is used as an index to the regions_score_histogram array, which is DAMOS_MAX_SCORE+1 size, it causes out of bounds array access.
The issues can be relatively easily reproduced like below. The sysfs write permission is required, though.
# ./damo start --damos_action lru_prio --damos_quota_space 100M \
--damos_quota_interval 1s
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/0/monitoring_attrs/intervals/sample_us
# echo 0 > contexts/0/monitoring_attrs/intervals/aggr_us
# echo commit > state
# dmesg
[...]
[ 131.329762] Oops: divide error: 0000 [#1] SMP NOPTI
[...]
[ 131.336089] RIP: 0010:damon_hot_score+0x27/0xd0
[...]
Fix the divide-by-zero intervals problems by explicitly handling the zero intervals in damon_max_nr_accesses(). Fix the out-of-bound array access by applying [0, DAMOS_MAX_SCORE] bounds before returning from damon_hot_score().
The issue was discovered [1] by Sashiko.
{
"affected": [],
"aliases": [
"CVE-2026-64458"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-25T10:17:30Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/ops-common: handle extreme intervals in damon_hot_score()\n\nFix three issues in damon_hot_score() that comes from wrong handling of\nextreme (zero or too high) monitoring intervals user setup.\n\nWhen the user sets sampling interval zero, damon_max_nr_accesses(), which\nis called from damon_hot_score(), causes a divide-by-zero. Needless to\nsay, it is a problem.\n\nWhen the user sets the aggregation interval zero, the function returns\nzero. It is wrong, since the real maximum nr_acceses in the setup should\nbe one. Worse yet, it can cause another divide-by-zero from its caller,\ndamon_hot_score(), since it uses damon_max_nr_accesses() return value as a\ndenominator.\n\nWhen the user sets the aggregation interval very high, damon_hot_score()\ncould return a value out of [0, DAMOS_MAX_SCORE] range. Since the return\nvalue is used as an index to the regions_score_histogram array, which is\nDAMOS_MAX_SCORE+1 size, it causes out of bounds array access.\n\nThe issues can be relatively easily reproduced like below. The sysfs\nwrite permission is required, though.\n\n # ./damo start --damos_action lru_prio --damos_quota_space 100M \\\n --damos_quota_interval 1s\n # cd /sys/kernel/mm/damon/admin/kdamonds/0\n # echo 0 \u003e contexts/0/monitoring_attrs/intervals/sample_us\n # echo 0 \u003e contexts/0/monitoring_attrs/intervals/aggr_us\n # echo commit \u003e state\n # dmesg\n [...]\n [ 131.329762] Oops: divide error: 0000 [#1] SMP NOPTI\n [...]\n [ 131.336089] RIP: 0010:damon_hot_score+0x27/0xd0\n [...]\n\nFix the divide-by-zero intervals problems by explicitly handling the zero\nintervals in damon_max_nr_accesses(). Fix the out-of-bound array access\nby applying [0, DAMOS_MAX_SCORE] bounds before returning from\ndamon_hot_score().\n\nThe issue was discovered [1] by Sashiko.",
"id": "GHSA-fhqc-6xwp-7x74",
"modified": "2026-07-25T12:31:36Z",
"published": "2026-07-25T12:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64458"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/35d4a3cf70a855b50e53189ac2f8463e20a02046"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/58321b4e6e4f0f412069ab27ccdd56292757343a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/74fef68d521150281e36cdaa20e9e1ee3e3aa146"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/76e415ea88d20f022ed5cfcf78c50e156a267e91"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9c8f31eaae6140ecadec0c07320498a944556de2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ef2ae10a4582bc92b7e944181bbd2f87f3d30f3a"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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