Fix CVE-2017-8779:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-8779

Patch copied from the bug reporter's 3rd-party repository:

https://github.com/guidovranken/rpcbomb/blob/master/rpcbind_patch.txt

diff --git a/src/rpcb_svc_com.c b/src/rpcb_svc_com.c
index 5862c26..e11f61b 100644
--- a/src/rpcb_svc_com.c
+++ b/src/rpcb_svc_com.c
@@ -48,6 +48,7 @@
 #include <rpc/rpc.h>
 #include <rpc/rpcb_prot.h>
 #include <rpc/svc_dg.h>
+#include <rpc/rpc_com.h>
 #include <netconfig.h>
 #include <errno.h>
 #include <syslog.h>
@@ -432,7 +433,7 @@ rpcbproc_taddr2uaddr_com(void *arg, struct svc_req *rqstp /*__unused*/,
 static bool_t
 xdr_encap_parms(XDR *xdrs, struct encap_parms *epp)
 {
-	return (xdr_bytes(xdrs, &(epp->args), (u_int *) &(epp->arglen), ~0));
+	return (xdr_bytes(xdrs, &(epp->args), (u_int *) &(epp->arglen), RPC_MAXDATASIZE));
 }
 
 /*
bmit' value='switch'/></form></td></tr>
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<div class='path'>path: <a href='/guix/log/?id=ec5ea1917a2706dfce006f6c3b87eb4f4b5dbf37'>root</a>/<a href='/guix/log/tests?id=ec5ea1917a2706dfce006f6c3b87eb4f4b5dbf37'>tests</a>/<a href='/guix/log/tests/scripts.scm?id=ec5ea1917a2706dfce006f6c3b87eb4f4b5dbf37'>scripts.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/scripts.scm?id=ec5ea1917a2706dfce006f6c3b87eb4f4b5dbf37&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-03-24 00:13:53 +0100'>2019-03-24</span></td><td><a href='/guix/commit/tests/scripts.scm?id=7b7e4e89c8a1a34e166a2755493e48035e8a78ab'>tests: Add missing import.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a followup to 22f95e028f038cee342f455dfc55bd32b804907c.

* tests/scripts.scm: Use (guix tests).
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-03-16 18:15:09 +0100'>2019-03-16</span></td><td><a href='/guix/commit/tests/scripts.scm?id=22f95e028f038cee342f455dfc55bd32b804907c'>tests: Add 'with-environment-variable'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/scripts.scm (with-environment-variable): Move to...
* guix/tests.scm (with-environment-variable): ... here.
* tests/build-utils.scm ("wrap-program, one input, multiple calls"):
Use it instead of 'setenv'.
</span></span></td><td>Ludovic Courtès</td></tr>