From ddb47d518ca10948d1f64a983cb9274720f691cd Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 14 May 2020 12:51:30 +0200 Subject: xdp: Clear grow memory in bpf_xdp_adjust_tail() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Clearing memory of tail when grow happens, because it is too easy to write a XDP_PASS program that extend the tail, which expose this memory to users that can run tcpdump. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Alexei Starovoitov Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/158945349039.97035.5262100484553494.stgit@firesoul --- net/core/filter.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/core/filter.c') diff --git a/net/core/filter.c b/net/core/filter.c index e7b033dad44e..a85eb538d4d6 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3427,6 +3427,10 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset) if (unlikely(data_end < xdp->data + ETH_HLEN)) return -EINVAL; + /* Clear memory area on grow, can contain uninit kernel memory */ + if (offset > 0) + memset(xdp->data_end, 0, offset); + xdp->data_end = data_end; return 0; -- cgit v1.2.3-59-g8ed1b