Commit 2a064262 authored by David Carlier's avatar David Carlier Committed by Tejun Heo
Browse files

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: default avatarDavid Carlier <devnexen@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 83236b2e

kernel/sched/ext_idle.c

+2 −2
Original line number Diff line number Diff line
@@ -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);