tipc: do sanity check payload of a netlink message

When we initialize nlmsghdr with no payload inside tipc_nl_compat_dumpit()
the parsing function returns -EINVAL. We fix it by making the parsing call
conditional.

Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Hoang Le <hoang.h.le@dektech.com.au>
Link: https://lore.kernel.org/r/20201215033151.76139-1-hoang.h.le@dektech.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index 82f1549..5a1ce64 100644 (file)
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -213,12 +213,14 @@ static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
        }
 
        info.attrs = attrbuf;
-       err = nlmsg_parse_deprecated(cb.nlh, GENL_HDRLEN, attrbuf,
-                                    tipc_genl_family.maxattr,
-                                    tipc_genl_family.policy, NULL);
-       if (err)
-               goto err_out;
 
+       if (nlmsg_len(cb.nlh) > 0) {
+               err = nlmsg_parse_deprecated(cb.nlh, GENL_HDRLEN, attrbuf,
+                                            tipc_genl_family.maxattr,
+                                            tipc_genl_family.policy, NULL);
+               if (err)
+                       goto err_out;
+       }
        do {
                int rem;