{"id":"CVE-2026-31458","state":"PUBLISHED","title":"mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]\n\nMultiple sysfs command paths dereference contexts_arr[0] without first\nverifying that kdamond->contexts->nr == 1.  A user can set nr_contexts to\n0 via sysfs while DAMON is running, causing NULL pointer dereferences.\n\nIn more detail, the issue can be triggered by privileged users like\nbelow.\n\nFirst, start DAMON and make contexts directory empty\n(kdamond->contexts->nr == 0).\n\n    # damo start\n    # cd /sys/kernel/mm/damon/admin/kdamonds/0\n    # echo 0 > contexts/nr_contexts\n\nThen, each of below commands will cause the NULL pointer dereference.\n\n    # echo update_schemes_stats > state\n    # echo update_schemes_tried_regions > state\n    # echo update_schemes_tried_bytes > state\n    # echo update_schemes_effective_quotas > state\n    # echo update_tuned_intervals > state\n\nGuard all commands (except OFF) at the entry point of\ndamon_sysfs_handle_cmd().","publishedAt":"2026-04-22T13:53:50.883Z","updatedAt":"2026-05-11T22:09:07.003Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"aba546061341b56e9ffb37e1eb661a3628b6ec12","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"1e8da792672481d603fa7cd0d815577220a3ee27","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"708033c231bd782858f4ddbb46ee874a5a5fbdab","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"bbe03ad3fb9e714191757ca7b41582f930be7be2","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"1bfe9fb5ed2667fb075682408b776b5273162615","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/damon/sysfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.18","versionType":"semver"},{"version":"6.6.131","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.80","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.21","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.11","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/damon/sysfs.c"]}],"references":["https://git.kernel.org/stable/c/aba546061341b56e9ffb37e1eb661a3628b6ec12","https://git.kernel.org/stable/c/1e8da792672481d603fa7cd0d815577220a3ee27","https://git.kernel.org/stable/c/708033c231bd782858f4ddbb46ee874a5a5fbdab","https://git.kernel.org/stable/c/bbe03ad3fb9e714191757ca7b41582f930be7be2","https://git.kernel.org/stable/c/1bfe9fb5ed2667fb075682408b776b5273162615"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31458.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31458","state":"PUBLISHED","datePublished":"2026-04-22T13:53:50.883Z","dateUpdated":"2026-05-11T22:09:07.003Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.092Z"},"containers":{"cna":{"title":"mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]\n\nMultiple sysfs command paths dereference contexts_arr[0] without first\nverifying that kdamond->contexts->nr == 1.  A user can set nr_contexts to\n0 via sysfs while DAMON is running, causing NULL pointer dereferences.\n\nIn more detail, the issue can be triggered by privileged users like\nbelow.\n\nFirst, start DAMON and make contexts directory empty\n(kdamond->contexts->nr == 0).\n\n    # damo start\n    # cd /sys/kernel/mm/damon/admin/kdamonds/0\n    # echo 0 > contexts/nr_contexts\n\nThen, each of below commands will cause the NULL pointer dereference.\n\n    # echo update_schemes_stats > state\n    # echo update_schemes_tried_regions > state\n    # echo update_schemes_tried_bytes > state\n    # echo update_schemes_effective_quotas > state\n    # echo update_tuned_intervals > state\n\nGuard all commands (except OFF) at the entry point of\ndamon_sysfs_handle_cmd()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"aba546061341b56e9ffb37e1eb661a3628b6ec12","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"1e8da792672481d603fa7cd0d815577220a3ee27","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"708033c231bd782858f4ddbb46ee874a5a5fbdab","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"bbe03ad3fb9e714191757ca7b41582f930be7be2","versionType":"git"},{"version":"0ac32b8affb5a384253dbb8339bd2d0e91add0b7","status":"affected","lessThan":"1bfe9fb5ed2667fb075682408b776b5273162615","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/damon/sysfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.18","versionType":"semver"},{"version":"6.6.131","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.80","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.21","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.11","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/damon/sysfs.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/aba546061341b56e9ffb37e1eb661a3628b6ec12"},{"url":"https://git.kernel.org/stable/c/1e8da792672481d603fa7cd0d815577220a3ee27"},{"url":"https://git.kernel.org/stable/c/708033c231bd782858f4ddbb46ee874a5a5fbdab"},{"url":"https://git.kernel.org/stable/c/bbe03ad3fb9e714191757ca7b41582f930be7be2"},{"url":"https://git.kernel.org/stable/c/1bfe9fb5ed2667fb075682408b776b5273162615"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:09:07.003Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18","versionEndExcluding":"6.6.131"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18","versionEndExcluding":"6.12.80"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18","versionEndExcluding":"6.18.21"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18","versionEndExcluding":"6.19.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}