sched_ext: Fix premature ops->priv publication in scx_alloc_and_add_sched()

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scx_alloc_and_add_sched() publishes @sch through ops->priv before allocating
the cgroup path. If that allocation fails, the unwind path clears ops->priv
and frees @sch immediately. scx_prog_sched() callers can dereference
ops->priv from RCU context the moment it is set, so freeing without a grace
period can use-after-free a concurrent kfunc caller.

Move the publication below the cgroup path allocation so that every failure
path after publication frees @sch through kobject_put(), whose release path
defers the freeing by a grace period.

Fixes: 105dcd005b ("sched_ext: Introduce scx_prog_sched()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

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Tejun Heo 2026-07-09 11:08:22 -10:00

parent db4e9defd2

commit 49b3378a75

1 changed files with 12 additions and 6 deletions

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kernel/sched/ext/ext.c

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