netfilter: nf_conntrack_dccp: fix skb_header_pointer API usages
Some occurences in the netfilter tree use skb_header_pointer() in the
following way ... struct dccp_hdr _dh, *dh; ... skb_header_pointer(skb,
dataoff, sizeof(_dh), &dh); ... where dh itself is a pointer that is
being passed as the copy buffer. Instead, we need to use &_dh as the
forth argument so that we're copying the data into an actual buffer that
sits on the stack. Currently, we probably could overwrite memory on the
stack (e.g. with a possibly mal-formed DCCP packet), but
unintentionally, as we only want the buffer to be placed into _dh
variable. Fixes: 2bc780499aa3 ("[NETFILTER]: nf_conntrack: add DCCP
protocol support")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>