netfilter: nft_meta: fix cgroup matching

We have to stop iterating on the rule expressions if the cgroup
mismatches. Moreover, make sure a non-full socket from the input path
leads us to a crash.

Fixes: ce67417 ("netfilter: nft_meta: add cgroup support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index 5197874372ec..d79ce88be77f 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -166,9 +166,8 @@ void nft_meta_get_eval(const struct nft_expr *expr,
                 dest->data[0] = out->group;
                 break;
         case NFT_META_CGROUP:
-                if (skb->sk == NULL)
-                        break;
-
+                if (skb->sk == NULL || !sk_fullsock(skb->sk))
+                        goto err;
                 dest->data[0] = skb->sk->sk_classid;
                 break;
         default: