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 <brouer@xxxxxxxxxx> Acked-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> --- net/core/filter.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 40e749d57cc1..7af583648c8d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3438,6 +3438,10 @@ 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;
