From: Florian Westphal <fw@xxxxxxxxx> commit 7eaecf7963c1c8f62d62c6a8e7c439b0e7f2d365 upstream. syzbot reports just another NULL deref crash because of missing test for presence of the attribute. Reported-by: syzbot+cf23983d697c26c34f60@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: b96af92d6eaf9fadd ("netfilter: nf_tables: implement Passive OS fingerprint module in nft_osf") Signed-off-by: Florian Westphal <fw@xxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/netfilter/nft_osf.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/netfilter/nft_osf.c +++ b/net/netfilter/nft_osf.c @@ -61,6 +61,9 @@ static int nft_osf_init(const struct nft int err; u8 ttl; + if (!tb[NFTA_OSF_DREG]) + return -EINVAL; + if (tb[NFTA_OSF_TTL]) { ttl = nla_get_u8(tb[NFTA_OSF_TTL]); if (ttl > 2)