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Subject[PATCH 5.0 191/238] svcrpc: fix UDP on servers with lots of threads
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: J. Bruce Fields <bfields@redhat.com>

commit b7e5034cbecf5a65b7bfdc2b20a8378039577706 upstream.

James Pearson found that an NFS server stopped responding to UDP
requests if started with more than 1017 threads.

sv_max_mesg is about 2^20, so that is probably where the calculation
performed by

svc_sock_setbufsize(svsk->sk_sock,
(serv->sv_nrthreads+3) * serv->sv_max_mesg,
(serv->sv_nrthreads+3) * serv->sv_max_mesg);

starts to overflow an int.

Reported-by: James Pearson <jcpearson@gmail.com>
Tested-by: James Pearson <jcpearson@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/sunrpc/svcsock.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -349,12 +349,16 @@ static ssize_t svc_recvfrom(struct svc_r
/*
* Set socket snd and rcv buffer lengths
*/
-static void svc_sock_setbufsize(struct socket *sock, unsigned int snd,
- unsigned int rcv)
+static void svc_sock_setbufsize(struct svc_sock *svsk, unsigned int nreqs)
{
+ unsigned int max_mesg = svsk->sk_xprt.xpt_server->sv_max_mesg;
+ struct socket *sock = svsk->sk_sock;
+
+ nreqs = min(nreqs, INT_MAX / 2 / max_mesg);
+
lock_sock(sock->sk);
- sock->sk->sk_sndbuf = snd * 2;
- sock->sk->sk_rcvbuf = rcv * 2;
+ sock->sk->sk_sndbuf = nreqs * max_mesg * 2;
+ sock->sk->sk_rcvbuf = nreqs * max_mesg * 2;
sock->sk->sk_write_space(sock->sk);
release_sock(sock->sk);
}
@@ -516,9 +520,7 @@ static int svc_udp_recvfrom(struct svc_r
* provides an upper bound on the number of threads
* which will access the socket.
*/
- svc_sock_setbufsize(svsk->sk_sock,
- (serv->sv_nrthreads+3) * serv->sv_max_mesg,
- (serv->sv_nrthreads+3) * serv->sv_max_mesg);
+ svc_sock_setbufsize(svsk, serv->sv_nrthreads + 3);

clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
skb = NULL;
@@ -681,9 +683,7 @@ static void svc_udp_init(struct svc_sock
* receive and respond to one request.
* svc_udp_recvfrom will re-adjust if necessary
*/
- svc_sock_setbufsize(svsk->sk_sock,
- 3 * svsk->sk_xprt.xpt_server->sv_max_mesg,
- 3 * svsk->sk_xprt.xpt_server->sv_max_mesg);
+ svc_sock_setbufsize(svsk, 3);

/* data might have come in before data_ready set up */
set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

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