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Commit b7e5034c authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

svcrpc: fix UDP on servers with lots of threads 



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: default avatarJames Pearson <jcpearson@gmail.com>
Tested-by: default avatarJames Pearson <jcpearson@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 8820bcaa

net/sunrpc/svcsock.c

+10 −10
Original line number Diff line number Diff line
@@ -349,12 +349,16 @@ static ssize_t svc_recvfrom(struct svc_rqst *rqstp, struct kvec *iov, 
/*

 * 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_rqst *rqstp) 
	     * 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 *svsk, struct svc_serv *serv) 
	 * 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);