mm/memory_hotplug: prevent accessing by index=-1

nid may be equal to NUMA_NO_NODE=-1.  Prevent accessing node_data array by
invalid index with check for nid.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Link: https://lkml.kernel.org/r/20240606080659.18525-1-abelova@astralinux.ru
Fixes: e83a437faa62 ("mm/memory_hotplug: introduce "auto-movable" online policy")
Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 171ad975c7cfd2dd20c890e76c640a48b963f7a0..f7580ec805386fc04ec931122e16ac3e6ef4687a 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -846,7 +846,6 @@ static bool auto_movable_can_online_movable(int nid, struct memory_group *group,
        unsigned long kernel_early_pages, movable_pages;
        struct auto_movable_group_stats group_stats = {};
        struct auto_movable_stats stats = {};
-       pg_data_t *pgdat = NODE_DATA(nid);
        struct zone *zone;
        int i;
 
@@ -857,6 +856,8 @@ static bool auto_movable_can_online_movable(int nid, struct memory_group *group,
                        auto_movable_stats_account_zone(&stats, zone);
        } else {
                for (i = 0; i < MAX_NR_ZONES; i++) {
+                       pg_data_t *pgdat = NODE_DATA(nid);
+
                        zone = pgdat->node_zones + i;
                        if (populated_zone(zone))
                                auto_movable_stats_account_zone(&stats, zone);