{"id":"CVE-2026-53328","summary":"sched_ext: Don't warn on NULL cgrp_moving_from in scx_cgroup_move_task()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Don't warn on NULL cgrp_moving_from in scx_cgroup_move_task()\n\nA WARN fires when systemd's user manager writes \"+cpu +memory +pids\" to\nits own subtree_control while a sched_ext scheduler is loaded:\n\n  WARNING: at kernel/sched/ext.c:3227 scx_cgroup_move_task+0xa8/0xb0\n   scx_cgroup_move_task+0xa8/0xb0\n   sched_move_task+0x134/0x290\n   cpu_cgroup_attach+0x39/0x70\n   cgroup_migrate_execute+0x37d/0x450\n   cgroup_update_dfl_csses+0x1e3/0x270\n   cgroup_subtree_control_write+0x3e7/0x440\n\nscx_cgroup_can_attach() arms cgrp_moving_from only when a task's cpu\ncgroup changes. It can still be NULL when scx_cgroup_move_task() runs,\nthrough this sequence:\n\n  Step                               Result\n  ---------------------------------  ----------------------------------\n  1. cpu enabled on cgroup G         cpu css = A\n  2. cpu toggled off then on for G   A killed, B created (same cgroup)\n  3. an exiting task keeps A alive   migration skips it, A now stale\n  4. +memory migrates G              stale A vs current B pulls cpu in\n  5. cpu attach runs for all tasks   hits a live, cpu-unchanged task\n  6. scx_cgroup_move_task() on it    cgrp_moving_from NULL -\u003e WARN\n\nThe mismatch is that scx_cgroup_can_attach() keys on cgroup identity\nwhile migration drives the move on css identity, so a NULL cgrp_moving_from\nhere is a legitimate css-only migration, not a missing prep.\n\nThe call is already gated on cgrp_moving_from, so just drop the warning.\nops.cgroup_prep_move() and ops.cgroup_move() stay paired.","modified":"2026-07-08T08:13:43.745521338Z","published":"2026-07-01T13:32:14.030Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53328.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/02e545c4297a26dbbc41df81b831e7f605bcd306"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0ffcad63b19a1cadb475c9f405a93607fdcd0d7c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bc75f5951fac4e49d175c4433fc08fb1ec01172f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cdff2eb97be147d2ce52ac1327841068781f25dc"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53328.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53328"},{"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":"8195136669661fdfe54e9a8923c33b31c92fc1da"},{"fixed":"cdff2eb97be147d2ce52ac1327841068781f25dc"},{"fixed":"0ffcad63b19a1cadb475c9f405a93607fdcd0d7c"},{"fixed":"bc75f5951fac4e49d175c4433fc08fb1ec01172f"},{"fixed":"02e545c4297a26dbbc41df81b831e7f605bcd306"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53328.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.12.0"},{"fixed":"6.12.94"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53328.json"}}],"schema_version":"1.7.5"}