On Thu, Jun 10, 2021 at 07:43:34PM +0200, Pablo Neira Ayuso wrote: > On Thu, Jun 10, 2021 at 04:23:16PM +0200, Phil Sutter wrote: > > Since user space does not generate a payload dependency, plain sctp > > chunk matches cause searching in non-SCTP packets, too. Avoid this > > potential mis-interpretation of packet data by checking pkt->tprot. > > > > Fixes: 133dc203d77df ("netfilter: nft_exthdr: Support SCTP chunks") > > Signed-off-by: Phil Sutter <phil@xxxxxx> > > --- > > net/netfilter/nft_exthdr.c | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c > > index 7f705b5c09de8..1093bb83f8aeb 100644 > > --- a/net/netfilter/nft_exthdr.c > > +++ b/net/netfilter/nft_exthdr.c > > @@ -312,6 +312,9 @@ static void nft_exthdr_sctp_eval(const struct nft_expr *expr, > > const struct sctp_chunkhdr *sch; > > struct sctp_chunkhdr _sch; > > > > + if (!pkt->tprot_set || pkt->tprot != IPPROTO_SCTP) > > + goto err; > > nft_set_pktinfo_unspec() already initializes pkt->tprot to zero. > > I think it's safe to simplify this to: > > if (pkt->tprot != IPPROTO_SCTP) Are you sure? Checking the spots that (should) initialize tprot/tprot_set, in nft_do_chain_inet() it seems that if state->pf is neither NFPROTO_IPV4 nor NFPROTO_IPV6, nft_do_chain() is called without prior init. Maybe default case should call nft_set_pktinfo_unspec()? BTW: The final return call in nft_do_chain_inet_ingress() is dead code, right? Thanks, Phil