tools: ynl-gen: make sure we validate subtype of array-nest

ArrayNest AKA indexed-array support currently skips inner type
validation. We count the attributes and then we parse them,
make sure we call validate, too. Otherwise buggy / unexpected
kernel response may lead to crashes.

Fixes: be5bea1cc0 ("net: add basic C code generators for Netlink")
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20250414211851.602096-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/pyynl/ynl_gen_c.py

@@ -714,8 +714,11 @@ class TypeArrayNest(Type):
     def _attr_get(self, ri, var):
         local_vars = ['const struct nlattr *attr2;']
         get_lines = [f'attr_{self.c_name} = attr;',
-                     'ynl_attr_for_each_nested(attr2, attr)',
-                     f'\t{var}->n_{self.c_name}++;']
+                     'ynl_attr_for_each_nested(attr2, attr) {',
+                     '\tif (ynl_attr_validate(yarg, attr2))',
+                     '\t\treturn YNL_PARSE_CB_ERROR;',
+                     f'\t{var}->n_{self.c_name}++;',
+                     '}']
         return get_lines, None, local_vars