From 2a064262eb378263792cf1fb044de631ac41bcc5 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Wed, 25 Feb 2026 21:15:23 +0000 Subject: [PATCH] sched_ext: Fix out-of-bounds access in scx_idle_init_masks() scx_idle_node_masks is allocated with num_possible_nodes() elements but indexed by NUMA node IDs via for_each_node(). On systems with non-contiguous NUMA node numbering (e.g. nodes 0 and 4), node IDs can exceed the array size, causing out-of-bounds memory corruption. Use nr_node_ids instead, which represents the maximum node ID range and is the correct size for arrays indexed by node ID. Fixes: 7c60329e3521 ("sched_ext: Add NUMA-awareness to the default idle selection policy") Signed-off-by: David Carlier Signed-off-by: Tejun Heo --- kernel/sched/ext_idle.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index 3d9d404d5cd2..e2da6c3968a6 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -663,8 +663,8 @@ void scx_idle_init_masks(void) BUG_ON(!alloc_cpumask_var(&scx_idle_global_masks.cpu, GFP_KERNEL)); BUG_ON(!alloc_cpumask_var(&scx_idle_global_masks.smt, GFP_KERNEL)); - /* Allocate per-node idle cpumasks */ - scx_idle_node_masks = kcalloc(num_possible_nodes(), + /* Allocate per-node idle cpumasks (use nr_node_ids for non-contiguous NUMA nodes) */ + scx_idle_node_masks = kcalloc(nr_node_ids, sizeof(*scx_idle_node_masks), GFP_KERNEL); BUG_ON(!scx_idle_node_masks);