Bug 186604

Created attachment 126761 [details]
patch to use current time as the initial XID

compile tested only -- attached patch gives a general idea about how this might
be fixed.

here's a patch against 2.6.16 that i worked up with trond's help.  our customer has tried this in the SLES 
9 kernel, and found it to eliminate their issue.

the customer also remarked that net_random_init(), the function used to seed the net_random() random 
number generator, does not exist in 2.6.5.  i haven't looked at 2.6.9, but if net_random_init() does not 
exist there, imo it should be backported.

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 4dd5b3c..02060d0 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -41,7 +41,7 @@
 #include <linux/types.h>
 #include <linux/interrupt.h>
 #include <linux/workqueue.h>
-#include <linux/random.h>
+#include <linux/net.h>
 
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/metrics.h>
@@ -830,7 +830,7 @@ static inline u32 xprt_alloc_xid(struct 
 
 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 {
-	get_random_bytes(&xprt->xid, sizeof(xprt->xid));
+	xprt->xid = net_random();
 }
 
 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 4b4e7df..21006b1 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -930,6 +930,13 @@ static void xs_udp_timer(struct rpc_task
 	xprt_adjust_cwnd(task, -ETIMEDOUT);
 }
 
+static unsigned short xs_get_random_port(void)
+{
+	unsigned short range = xprt_max_resvport - xprt_min_resvport;
+	unsigned short rand = (unsigned short) net_random() % range;
+	return rand + xprt_min_resvport;
+}
+
 /**
  * xs_set_port - reset the port number in the remote endpoint address
  * @xprt: generic transport
@@ -1275,7 +1282,7 @@ int xs_setup_udp(struct rpc_xprt *xprt, 
 	memset(xprt->slot, 0, slot_table_size);
 
 	xprt->prot = IPPROTO_UDP;
-	xprt->port = xprt_max_resvport;
+	xprt->port = xs_get_random_port();
 	xprt->tsh_size = 0;
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	/* XXX: header size can vary due to auth type, IPv6, etc. */
@@ -1317,7 +1324,7 @@ int xs_setup_tcp(struct rpc_xprt *xprt, 
 	memset(xprt->slot, 0, slot_table_size);
 
 	xprt->prot = IPPROTO_TCP;
-	xprt->port = xprt_max_resvport;
+	xprt->port = xs_get_random_port();
 	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

Created attachment 138810 [details]
Proposed patch

The patch described in Comment #2 seems to do the trick.

committed in stream U5 build 42.25. A test kernel with this patch is available
from http://people.redhat.com/~jbaron/rhel4/

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2007-0304.html