netfilter: nf_tables: fix potential oops when dumping sets

Commit c9c8e48597 (netfilter: nf_tables: dump sets in all existing families)
changed nft_ctx_init_from_setattr() to only look up the address family if it
is not NFPROTO_UNSPEC. However if it is NFPROTO_UNSPEC and a table attribute
is given, nftables_afinfo_lookup() will dereference the NULL afi pointer.

Fix by checking for non-NULL afi and also move a check added by that commit
to the proper position.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 2a22a186eb3d..3c5a219f4242 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1943,6 +1943,9 @@ static int nft_ctx_init_from_setattr(struct nft_ctx *ctx,
         }
 
         if (nla[NFTA_SET_TABLE] != NULL) {
+                if (afi == NULL)
+                        return -EAFNOSUPPORT;
+
                 table = nf_tables_table_lookup(afi, nla[NFTA_SET_TABLE]);
                 if (IS_ERR(table))
                         return PTR_ERR(table);
@@ -2428,6 +2431,8 @@ static int nf_tables_delset(struct sock *nlsk, struct sk_buff *skb,
         struct nft_ctx ctx;
         int err;
 
+        if (nfmsg->nfgen_family == NFPROTO_UNSPEC)
+                return -EAFNOSUPPORT;
         if (nla[NFTA_SET_TABLE] == NULL)
                 return -EINVAL;
 
@@ -2435,9 +2440,6 @@ static int nf_tables_delset(struct sock *nlsk, struct sk_buff *skb,
         if (err < 0)
                 return err;
 
-        if (nfmsg->nfgen_family == NFPROTO_UNSPEC)
-                return -EAFNOSUPPORT;
-
         set = nf_tables_set_lookup(ctx.table, nla[NFTA_SET_NAME]);
         if (IS_ERR(set))
                 return PTR_ERR(set);