[PATCH net] net: genl: fix error path memory leak in policy dumping

[Jakub Kicinski <kuba@kernel.org>]

If construction of the array of policies fails when recording
non-first policy we need to unwind.

Reported-by: syzbot+dc54d9ba8153b216cae0@syzkaller.appspotmail.com
Fixes: 50a896cf2d6f ("genetlink: properly support per-op policy dumping")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/netlink/genetlink.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 1afca2a6c2ac..57010927e20a 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1174,13 +1174,17 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
 							     op.policy,
 							     op.maxattr);
 			if (err)
-				return err;
+				goto err_free_state;
 		}
 	}
 
 	if (!ctx->state)
 		return -ENODATA;
 	return 0;
+
+err_free_state:
+	netlink_policy_dump_free(ctx->state);
+	return err;
 }
 
 static void *ctrl_dumppolicy_prep(struct sk_buff *skb,
-- 
2.37.2