{"id":"CVE-2026-64458","title":"mm/damon/ops-common: handle extreme intervals in damon_hot_score()","summary":"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) m…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 58321b4e6e4f0f412069ab27ccdd56292757343a","Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 74fef68d521150281e36cdaa20e9e1ee3e3aa146","Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < ef2ae10a4582bc92b7e944181bbd2f87f3d30f3a","Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 9c8f31eaae6140ecadec0c07320498a944556de2","Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 76e415ea88d20f022ed5cfcf78c50e156a267e91","Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 35d4a3cf70a855b50e53189ac2f8463e20a02046","Linux 5.16"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:38:57.314626Z"},"published":"2026-07-25","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:44:52.652Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64458","references":[{"url":"https://git.kernel.org/stable/c/58321b4e6e4f0f412069ab27ccdd56292757343a"},{"url":"https://git.kernel.org/stable/c/74fef68d521150281e36cdaa20e9e1ee3e3aa146"},{"url":"https://git.kernel.org/stable/c/ef2ae10a4582bc92b7e944181bbd2f87f3d30f3a"},{"url":"https://git.kernel.org/stable/c/9c8f31eaae6140ecadec0c07320498a944556de2"},{"url":"https://git.kernel.org/stable/c/76e415ea88d20f022ed5cfcf78c50e156a267e91"},{"url":"https://git.kernel.org/stable/c/35d4a3cf70a855b50e53189ac2f8463e20a02046"}],"tags":["cve.org"],"epss":0.0018,"epssPercentile":0.07644,"ingestedAt":"2026-11-06T16:57:43.174Z","slug":"CVE-2026-64458","body":"## Overview\n\nIn 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 > contexts/0/monitoring_attrs/intervals/sample_us\n    # echo 0 > contexts/0/monitoring_attrs/intervals/aggr_us\n    # echo commit > 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.\n\n## Affected\n\n- `Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 58321b4e6e4f0f412069ab27ccdd56292757343a`\n- `Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 74fef68d521150281e36cdaa20e9e1ee3e3aa146`\n- `Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < ef2ae10a4582bc92b7e944181bbd2f87f3d30f3a`\n- `Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 9c8f31eaae6140ecadec0c07320498a944556de2`\n- `Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 76e415ea88d20f022ed5cfcf78c50e156a267e91`\n- `Linux >= 198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f < 35d4a3cf70a855b50e53189ac2f8463e20a02046`\n- `Linux 5.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}