queue-4.19/svcrpc-fix-udp-on-servers-with-lots-of-threads.patch

   1 From b7e5034cbecf5a65b7bfdc2b20a8378039577706 Mon Sep 17 00:00:00 2001
   2 From: "J. Bruce Fields" <bfields@redhat.com>
   3 Date: Wed, 20 Feb 2019 12:54:50 -0500
   4 Subject: svcrpc: fix UDP on servers with lots of threads
   5
   6 From: J. Bruce Fields <bfields@redhat.com>
   7
   8 commit b7e5034cbecf5a65b7bfdc2b20a8378039577706 upstream.
   9
  10 James Pearson found that an NFS server stopped responding to UDP
  11 requests if started with more than 1017 threads.
  12
  13 sv_max_mesg is about 2^20, so that is probably where the calculation
  14 performed by
  15
  16         svc_sock_setbufsize(svsk->sk_sock,
  17                             (serv->sv_nrthreads+3) * serv->sv_max_mesg,
  18                             (serv->sv_nrthreads+3) * serv->sv_max_mesg);
  19
  20 starts to overflow an int.
  21
  22 Reported-by: James Pearson <jcpearson@gmail.com>
  23 Tested-by: James Pearson <jcpearson@gmail.com>
  24 Cc: stable@vger.kernel.org
  25 Signed-off-by: J. Bruce Fields <bfields@redhat.com>
  26 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  27
  28 ---
  29  net/sunrpc/svcsock.c |   20 ++++++++++----------
  30  1 file changed, 10 insertions(+), 10 deletions(-)
  31
  32 --- a/net/sunrpc/svcsock.c
  33 +++ b/net/sunrpc/svcsock.c
  34 @@ -381,12 +381,16 @@ static int svc_partial_recvfrom(struct s
  35  /*
  36   * Set socket snd and rcv buffer lengths
  37   */
  38 -static void svc_sock_setbufsize(struct socket *sock, unsigned int snd,
  39 -                               unsigned int rcv)
  40 +static void svc_sock_setbufsize(struct svc_sock *svsk, unsigned int nreqs)
  41  {
  42 +       unsigned int max_mesg = svsk->sk_xprt.xpt_server->sv_max_mesg;
  43 +       struct socket *sock = svsk->sk_sock;
  44 +
  45 +       nreqs = min(nreqs, INT_MAX / 2 / max_mesg);
  46 +
  47         lock_sock(sock->sk);
  48 -       sock->sk->sk_sndbuf = snd * 2;
  49 -       sock->sk->sk_rcvbuf = rcv * 2;
  50 +       sock->sk->sk_sndbuf = nreqs * max_mesg * 2;
  51 +       sock->sk->sk_rcvbuf = nreqs * max_mesg * 2;
  52         sock->sk->sk_write_space(sock->sk);
  53         release_sock(sock->sk);
  54  }
  55 @@ -548,9 +552,7 @@ static int svc_udp_recvfrom(struct svc_r
  56              * provides an upper bound on the number of threads
  57              * which will access the socket.
  58              */
  59 -           svc_sock_setbufsize(svsk->sk_sock,
  60 -                               (serv->sv_nrthreads+3) * serv->sv_max_mesg,
  61 -                               (serv->sv_nrthreads+3) * serv->sv_max_mesg);
  62 +           svc_sock_setbufsize(svsk, serv->sv_nrthreads + 3);
  63
  64         clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
  65         skb = NULL;
  66 @@ -718,9 +720,7 @@ static void svc_udp_init(struct svc_sock
  67          * receive and respond to one request.
  68          * svc_udp_recvfrom will re-adjust if necessary
  69          */
  70 -       svc_sock_setbufsize(svsk->sk_sock,
  71 -                           3 * svsk->sk_xprt.xpt_server->sv_max_mesg,
  72 -                           3 * svsk->sk_xprt.xpt_server->sv_max_mesg);
  73 +       svc_sock_setbufsize(svsk, 3);
  74
  75         /* data might have come in before data_ready set up */
  76         set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);