netfilter: nft_osf: check if attribute is present

If the attribute is not sent, eg. old libnftnl binary, then
tb[NFTA_OSF_TTL] is NULL and kernel crashes from the _init path.

Fixes: a218dc82f0b5 ("netfilter: nft_osf: Add ttl option support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index ca5e5d8c5ef8b91cd61cb039d652f4549c343948..b13618c764ec296377778ee405b9067515ada25a 100644 (file)
--- a/net/netfilter/nft_osf.c
+++ b/net/netfilter/nft_osf.c
@@ -50,7 +50,7 @@ static int nft_osf_init(const struct nft_ctx *ctx,
        int err;
        u8 ttl;
 
-       if (nla_get_u8(tb[NFTA_OSF_TTL])) {
+       if (tb[NFTA_OSF_TTL]) {
                ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
                if (ttl > 2)
                        return -EINVAL;