{"id":"CVE-2026-64458","summary":"mm/damon/ops-common: handle extreme intervals in damon_hot_score()","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.","modified":"2026-07-27T04:03:20.032052637Z","published":"2026-07-25T08:51:26.072Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64458.json"},"references":[{"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"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64458.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64458"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"198f0f4c58b9f481e4e51c8c70a6ab9852bbab7f"},{"fixed":"58321b4e6e4f0f412069ab27ccdd56292757343a"},{"fixed":"74fef68d521150281e36cdaa20e9e1ee3e3aa146"},{"fixed":"ef2ae10a4582bc92b7e944181bbd2f87f3d30f3a"},{"fixed":"9c8f31eaae6140ecadec0c07320498a944556de2"},{"fixed":"76e415ea88d20f022ed5cfcf78c50e156a267e91"},{"fixed":"35d4a3cf70a855b50e53189ac2f8463e20a02046"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64458.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64458.json"}}],"schema_version":"1.7.5"}