netlink: fix policy dump for int with validation callback

Recent devlink change added validation of an integer value
via NLA_POLICY_VALIDATE_FN, for sparse enums. Handle this
in policy dump. We can't extract any info out of the callback,
so report only the type.

Fixes: 429ac6211494 ("devlink: define enum for attr types of dynamic attributes")
Reported-by: syzbot+01eb26848144516e7f0a@syzkaller.appspotmail.com
Link: https://patch.msgid.link/20250509212751.1905149-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/netlink.h b/include/net/netlink.h
index 82e07e272290a970faba014444ab57d04f6ef91c..90a560dc167a9c78d2dbc2015fa8cf4debca49c2 100644 (file)
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -321,7 +321,13 @@ enum nla_policy_validation {
  *    All other            Unused - but note that it's a union
  *
  * Meaning of `validate' field, use via NLA_POLICY_VALIDATE_FN:
+ *    NLA_U8, NLA_U16,
+ *    NLA_U32, NLA_U64,
+ *    NLA_S8, NLA_S16,
+ *    NLA_S32, NLA_S64,
+ *    NLA_MSECS,
  *    NLA_BINARY           Validation function called for the attribute.
+ *
  *    All other            Unused - but note that it's a union
  *
  * Example:

diff --git a/net/netlink/policy.c b/net/netlink/policy.c
index 1f8909c16f14cbbe335a43db069848fa970427e7..99458da6be322b1b18ed4ec9b73282595d2d015d 100644 (file)
--- a/net/netlink/policy.c
+++ b/net/netlink/policy.c
@@ -311,6 +311,8 @@ __netlink_policy_dump_write_attr(struct netlink_policy_dump_state *state,
                                              NL_POLICY_TYPE_ATTR_PAD))
                                goto nla_put_failure;
                        break;
+               } else if (pt->validation_type == NLA_VALIDATE_FUNCTION) {
+                       break;
                }
 
                nla_get_range_unsigned(pt, &range);
@@ -340,6 +342,9 @@ __netlink_policy_dump_write_attr(struct netlink_policy_dump_state *state,
                else
                        type = NL_ATTR_TYPE_SINT;
 
+               if (pt->validation_type == NLA_VALIDATE_FUNCTION)
+                       break;
+
                nla_get_range_signed(pt, &range);
 
                if (nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_S,