net: embed nr_ids in the xps maps

Embed nr_ids (the number of cpu for the xps cpus map, and the number of
rxqs for the xps cpus map) in dev_maps. That will help not accessing out
of bound memory if those values change after dev_maps was allocated.

Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c38534c55ea1..09e73f5a8c78 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -772,6 +772,9 @@ struct xps_map {
 /*
  * This structure holds all XPS maps for device.  Maps are indexed by CPU.
  *
+ * We keep track of the number of cpus/rxqs used when the struct is allocated,
+ * in nr_ids. This will help not accessing out-of-bound memory.
+ *
  * We keep track of the number of traffic classes used when the struct is
  * allocated, in num_tc. This will be used to navigate the maps, to ensure we're
  * not crossing its upper bound, as the original dev->num_tc can be updated in
@@ -779,6 +782,7 @@ struct xps_map {
  */
 struct xps_dev_maps {
 	struct rcu_head rcu;
+	unsigned int nr_ids;
 	s16 num_tc;
 	struct xps_map __rcu *attr_map[]; /* Either CPUs map or RXQs map */
 };