{"id":"CVE-2026-31457","state":"PUBLISHED","title":"mm/damon/sysfs: check contexts->nr in repeat_call_fn","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs: check contexts->nr in repeat_call_fn\n\ndamon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(),\ndamon_sysfs_upd_schemes_stats(), and\ndamon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr. \nIf nr_contexts is set to 0 via sysfs while DAMON is running, these\nfunctions dereference contexts_arr[0] and cause a NULL pointer\ndereference.  Add the missing check.\n\nFor example, the issue can be reproduced using DAMON sysfs interface and\nDAMON user-space tool (damo) [1] like below.\n\n    $ sudo damo start --refresh_interval 1s\n    $ echo 0 | sudo tee \\\n            /sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts","publishedAt":"2026-04-22T13:53:50.220Z","updatedAt":"2026-05-11T22:09:05.878Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d809a7c64ba8229286b333c0cba03b1cdfb50238","status":"affected","lessThan":"3527e9fdc38570cea0f6ddb7a2c9303d4044b217","versionType":"git"},{"version":"d809a7c64ba8229286b333c0cba03b1cdfb50238","status":"affected","lessThan":"652cd0641a763dd0e846b0d12814977fadb2b7d8","versionType":"git"},{"version":"d809a7c64ba8229286b333c0cba03b1cdfb50238","status":"affected","lessThan":"6557004a8b59c7701e695f02be03c7e20ed1cc15","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":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","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/3527e9fdc38570cea0f6ddb7a2c9303d4044b217","https://git.kernel.org/stable/c/652cd0641a763dd0e846b0d12814977fadb2b7d8","https://git.kernel.org/stable/c/6557004a8b59c7701e695f02be03c7e20ed1cc15"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31457.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31457","state":"PUBLISHED","datePublished":"2026-04-22T13:53:50.220Z","dateUpdated":"2026-05-11T22:09:05.878Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.092Z"},"containers":{"cna":{"title":"mm/damon/sysfs: check contexts->nr in repeat_call_fn","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs: check contexts->nr in repeat_call_fn\n\ndamon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(),\ndamon_sysfs_upd_schemes_stats(), and\ndamon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr. \nIf nr_contexts is set to 0 via sysfs while DAMON is running, these\nfunctions dereference contexts_arr[0] and cause a NULL pointer\ndereference.  Add the missing check.\n\nFor example, the issue can be reproduced using DAMON sysfs interface and\nDAMON user-space tool (damo) [1] like below.\n\n    $ sudo damo start --refresh_interval 1s\n    $ echo 0 | sudo tee \\\n            /sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d809a7c64ba8229286b333c0cba03b1cdfb50238","status":"affected","lessThan":"3527e9fdc38570cea0f6ddb7a2c9303d4044b217","versionType":"git"},{"version":"d809a7c64ba8229286b333c0cba03b1cdfb50238","status":"affected","lessThan":"652cd0641a763dd0e846b0d12814977fadb2b7d8","versionType":"git"},{"version":"d809a7c64ba8229286b333c0cba03b1cdfb50238","status":"affected","lessThan":"6557004a8b59c7701e695f02be03c7e20ed1cc15","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":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","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/3527e9fdc38570cea0f6ddb7a2c9303d4044b217"},{"url":"https://git.kernel.org/stable/c/652cd0641a763dd0e846b0d12814977fadb2b7d8"},{"url":"https://git.kernel.org/stable/c/6557004a8b59c7701e695f02be03c7e20ed1cc15"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:09:05.878Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18.21"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.19.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}