{"id":"CVE-2026-52980","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Clear rel_deadline when initializing forked entities\n\nA yield-triggered crash can happen when a newly forked sched_entity\nenters the fair class with se->rel…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Clear rel_deadline when initializing forked entities\n\nA yield-triggered crash can happen when a newly forked sched_entity\nenters the fair class with se->rel…","severity":"none","published":"2026-06-24","updated":"2026-07-10","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-52980","references":[{"url":"https://git.kernel.org/stable/c/3da56dc063cd77b9c0b40add930767fab4e389f3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8f4a16200785f49cf02c5b71bdfe7a9dab63f23a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c71bf35caba12bfd9bc23e32b0bcd9e02d1cf1ac","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f3c16e1f4a314a20717ab90a41885f8111a242ab","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00122,"epssPercentile":0.02264,"ingestedAt":"2026-07-11T13:13:25.428Z","slug":"CVE-2026-52980","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Clear rel_deadline when initializing forked entities\n\nA yield-triggered crash can happen when a newly forked sched_entity\nenters the fair class with se->rel_deadline unexpectedly set.\n\nThe failing sequence is:\n\n  1. A task is forked while se->rel_deadline is still set.\n  2. __sched_fork() initializes vruntime, vlag and other sched_entity\n     state, but does not clear rel_deadline.\n  3. On the first enqueue, enqueue_entity() calls place_entity().\n  4. Because se->rel_deadline is set, place_entity() treats se->deadline\n     as a relative deadline and converts it to an absolute deadline by\n     adding the current vruntime.\n  5. However, the forked entity's deadline is not a valid inherited\n     relative deadline for this new scheduling instance, so the conversion\n     produces an abnormally large deadline.\n  6. If the task later calls sched_yield(), yield_task_fair() advances\n     se->vruntime to se->deadline.\n  7. The inflated vruntime is then used by the following enqueue path,\n     where the vruntime-derived key can overflow when multiplied by the\n     entity weight.\n  8. This corrupts cfs_rq->sum_w_vruntime, breaks EEVDF eligibility\n     calculation, and can eventually make all entities appear ineligible.\n     pick_next_entity() may then return NULL unexpectedly, leading to a\n     later NULL dereference.\n\nA captured trace shows the effect clearly. Before yield, the entity's\nvruntime was around:\n\n  9834017729983308\n\nAfter yield_task_fair() executed:\n\n  se->vruntime = se->deadline\n\nthe vruntime jumped to:\n\n  19668035460670230\n\nand the deadline was later advanced further to:\n\n  19668035463470230\n\nThis shows that the deadline had already become abnormally large before\nyield_task_fair() copied it into vruntime.\n\nrel_deadline is only meaningful when se->deadline really carries a\nrelative deadline that still needs to be placed against vruntime. A\nfreshly forked sched_entity should not inherit or retain this state.\nClear se->rel_deadline in __sched_fork(), together with the other\nsched_entity runtime state, so that the first enqueue does not interpret\nthe new entity's deadline as a stale relative deadline.\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":[]}