queue-5.1/tuntap-fix-dividing-by-zero-in-ebpf-queue-selection.patch

   1 From foo@baz Wed 15 May 2019 07:51:30 AM CEST
   2 From: Jason Wang <jasowang@redhat.com>
   3 Date: Wed, 8 May 2019 23:20:17 -0400
   4 Subject: tuntap: fix dividing by zero in ebpf queue selection
   5
   6 From: Jason Wang <jasowang@redhat.com>
   7
   8 [ Upstream commit a35d310f03a692bf4798eb309a1950a06a150620 ]
   9
  10 We need check if tun->numqueues is zero (e.g for the persist device)
  11 before trying to use it for modular arithmetic.
  12
  13 Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
  14 Fixes: 96f84061620c6("tun: add eBPF based queue selection method")
  15 Signed-off-by: Jason Wang <jasowang@redhat.com>
  16 Reviewed-by: Eric Dumazet <edumazet@google.com>
  17 Signed-off-by: David S. Miller <davem@davemloft.net>
  18 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  19 ---
  20  drivers/net/tun.c |    7 ++++++-
  21  1 file changed, 6 insertions(+), 1 deletion(-)
  22
  23 --- a/drivers/net/tun.c
  24 +++ b/drivers/net/tun.c
  25 @@ -596,13 +596,18 @@ static u16 tun_automq_select_queue(struc
  26  static u16 tun_ebpf_select_queue(struct tun_struct *tun, struct sk_buff *skb)
  27  {
  28         struct tun_prog *prog;
  29 +       u32 numqueues;
  30         u16 ret = 0;
  31
  32 +       numqueues = READ_ONCE(tun->numqueues);
  33 +       if (!numqueues)
  34 +               return 0;
  35 +
  36         prog = rcu_dereference(tun->steering_prog);
  37         if (prog)
  38                 ret = bpf_prog_run_clear_cb(prog->prog, skb);
  39
  40 -       return ret % tun->numqueues;
  41 +       return ret % numqueues;
  42  }
  43
  44  static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,