wireguard: allowedips: expand maximum node depth

In the allowedips self-test, nodes are inserted into the tree, but it
generated an even amount of nodes, but for checking maximum node depth,
there is of course the root node, which makes the total number
necessarily odd. With two few nodes added, it never triggered the
maximum depth check like it should have. So, add 129 nodes instead of
128 nodes, and do so with a more straightforward scheme, starting with
all the bits set, and shifting over one each time. Then increase the
maximum depth to 129, and choose a better name for that variable to
make it clear that it represents depth as opposed to bits.

Cc: [e-mail]
Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/wireguard/allowedips.c

···
 #include "allowedips.h"
 #include "peer.h"
 
-enum { MAX_ALLOWEDIPS_BITS = 128 };
+enum { MAX_ALLOWEDIPS_DEPTH = 129 };
 
 static struct kmem_cache *node_cache;
 
···
 		     struct allowedips_node __rcu *p, unsigned int *len)
 {
 	if (rcu_access_pointer(p)) {
-		if (WARN_ON(IS_ENABLED(DEBUG) && *len >= MAX_ALLOWEDIPS_BITS))
+		if (WARN_ON(IS_ENABLED(DEBUG) && *len >= MAX_ALLOWEDIPS_DEPTH))
 			return;
 		stack[(*len)++] = rcu_dereference_raw(p);
 	}
···
 
 static void root_free_rcu(struct rcu_head *rcu)
 {
-	struct allowedips_node *node, *stack[MAX_ALLOWEDIPS_BITS] = {
+	struct allowedips_node *node, *stack[MAX_ALLOWEDIPS_DEPTH] = {
 		container_of(rcu, struct allowedips_node, rcu) };
 	unsigned int len = 1;
 
···
 
 static void root_remove_peer_lists(struct allowedips_node *root)
 {
-	struct allowedips_node *node, *stack[MAX_ALLOWEDIPS_BITS] = { root };
+	struct allowedips_node *node, *stack[MAX_ALLOWEDIPS_DEPTH] = { root };
 	unsigned int len = 1;
 
 	while (len > 0 && (node = stack[--len])) {

drivers/net/wireguard/selftest/allowedips.c

···
 	wg_allowedips_remove_by_peer(&t, a, &mutex);
 	test_negative(4, a, 192, 168, 0, 1);
 
-	/* These will hit the WARN_ON(len >= MAX_ALLOWEDIPS_BITS) in free_node
+	/* These will hit the WARN_ON(len >= MAX_ALLOWEDIPS_DEPTH) in free_node
 	 * if something goes wrong.
 	 */
-	for (i = 0; i < MAX_ALLOWEDIPS_BITS; ++i) {
-		part = cpu_to_be64(~(1LLU << (i % 64)));
-		memset(&ip, 0xff, 16);
-		memcpy((u8 *)&ip + (i < 64) * 8, &part, 8);
+	for (i = 0; i < 64; ++i) {
+		part = cpu_to_be64(~0LLU << i);
+		memset(&ip, 0xff, 8);
+		memcpy((u8 *)&ip + 8, &part, 8);
+		wg_allowedips_insert_v6(&t, &ip, 128, a, &mutex);
+		memcpy(&ip, &part, 8);
+		memset((u8 *)&ip + 8, 0, 8);
 		wg_allowedips_insert_v6(&t, &ip, 128, a, &mutex);
 	}
-
+	memset(&ip, 0, 16);
+	wg_allowedips_insert_v6(&t, &ip, 128, a, &mutex);
 	wg_allowedips_free(&t, &mutex);
 
 	wg_allowedips_init(&t);