From: Tejun Heo Date: Mon, 11 May 2026 22:05:48 +0000 (-1000) Subject: sched_ext: Avoid UAF in scx_root_enable_workfn() init failure path X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9a415cc53711f2238e0f0ca8a6bcc796c003b127;p=thirdparty%2Fkernel%2Flinux.git sched_ext: Avoid UAF in scx_root_enable_workfn() init failure path In scx_root_enable_workfn(), put_task_struct(p) is called before scx_error() dereferences p->comm and p->pid. If the iterator's reference is the last drop, the task is freed synchronously and the deref becomes a UAF. Move put_task_struct() past scx_error(). Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260511214031.AF5E9C2BCB0@smtp.kernel.org/ Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Tejun Heo --- diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 1efd5d82b08b..9354da79e162 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -6973,10 +6973,10 @@ static void scx_root_enable_workfn(struct kthread_work *work) if (scx_get_task_state(p) != SCX_TASK_DEAD) scx_set_task_state(p, SCX_TASK_NONE); task_rq_unlock(rq, p, &rf); - put_task_struct(p); scx_task_iter_stop(&sti); scx_error(sch, "ops.init_task() failed (%d) for %s[%d]", ret, p->comm, p->pid); + put_task_struct(p); goto err_disable_unlock_all; }