netfilter: nft_tunnel: fix null-attribute check

else we get null deref when one of the attributes is missing, both
must be non-null.

Reported-by: syzbot+76d0b80493ac881ff77b@syzkaller.appspotmail.com
Fixes: aaecfdb5c5dd8ba ("netfilter: nf_tables: match on tunnel metadata")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_tunnel.c b/net/netfilter/nft_tunnel.c
index 3d4c2ae605a8e2c3ceee669570775cd5ebbb3e1e..d89c7c55303097060e514fbce0be57664e922130 100644 (file)
--- a/net/netfilter/nft_tunnel.c
+++ b/net/netfilter/nft_tunnel.c
@@ -76,7 +76,7 @@ static int nft_tunnel_get_init(const struct nft_ctx *ctx,
        struct nft_tunnel *priv = nft_expr_priv(expr);
        u32 len;
 
-       if (!tb[NFTA_TUNNEL_KEY] &&
+       if (!tb[NFTA_TUNNEL_KEY] ||
            !tb[NFTA_TUNNEL_DREG])
                return -EINVAL;