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    Subject[PATCH 5.15 140/279] udp: Validate checksum in udp_read_sock()
    Date
    From: Cong Wang <cong.wang@bytedance.com>

    [ Upstream commit 099f896f498a2b26d84f4ddae039b2c542c18b48 ]

    It turns out the skb's in sock receive queue could have bad checksums, as
    both ->poll() and ->recvmsg() validate checksums. We have to do the same
    for ->read_sock() path too before they are redirected in sockmap.

    Fixes: d7f571188ecf ("udp: Implement ->read_sock() for sockmap")
    Reported-by: Daniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: Cong Wang <cong.wang@bytedance.com>
    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    Acked-by: John Fastabend <john.fastabend@gmail.com>
    Link: https://lore.kernel.org/bpf/20211115044006.26068-1-xiyou.wangcong@gmail.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/ipv4/udp.c | 11 +++++++++++
    1 file changed, 11 insertions(+)

    diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
    index 2fffcf2b54f3f..2ce3fca545d37 100644
    --- a/net/ipv4/udp.c
    +++ b/net/ipv4/udp.c
    @@ -1808,6 +1808,17 @@ int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
    skb = skb_recv_udp(sk, 0, 1, &err);
    if (!skb)
    return err;
    +
    + if (udp_lib_checksum_complete(skb)) {
    + __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS,
    + IS_UDPLITE(sk));
    + __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS,
    + IS_UDPLITE(sk));
    + atomic_inc(&sk->sk_drops);
    + kfree_skb(skb);
    + continue;
    + }
    +
    used = recv_actor(desc, skb, 0, skb->len);
    if (used <= 0) {
    if (!copied)
    --
    2.33.0


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