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));
 }
 
 /*
' value='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>refs</a><a class='active' href='/guix/log/etc/substitutes'>log</a><a href='/guix/tree/etc/substitutes?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>tree</a><a href='/guix/commit/etc/substitutes?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>commit</a><a href='/guix/diff/etc/substitutes?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/etc/substitutes'>
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<option value='grep'>log msg</option>
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<option value='committer'>committer</option>
<option value='range'>range</option>
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<input class='txt' type='search' size='10' name='q' value=''/>
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<div class='path'>path: <a href='/guix/log/?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>root</a>/<a href='/guix/log/etc?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>etc</a>/<a href='/guix/log/etc/substitutes?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab'>substitutes</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/etc/substitutes?id=2cb678cd04f6a77626b0a7d9ff9cba9ba00bb9ab&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-07-10 00:11:00 +0200'>2020-07-10</span></td><td><a href='/guix/commit/etc/substitutes?id=d283bb960f927dd5f7bb8b96bc697221e4e8ad39'>maint: Remove traces of "berlin.guixsd.org".</a><span class='msg-avail'>...<span class='msg-tooltip'>The guixsd.org domain is no longer advertised since before in 1.0.0
release in May 2019.

* etc/substitutes/berlin.guixsd.org.pub: Rename to...
* etc/substitutes/berlin.guix.gnu.org.pub: ... this.
* etc/substitutes/ci.guix.gnu.org.pub,
etc/substitutes/ci.guix.info.pub: Adjust accordingly.
* gnu/services/base.scm (%default-authorized-guix-keys): Likewise.
* guix/build/download-nar.scm (urls-for-item): Likewise.
* guix/self.scm (miscellaneous-files): Likewise.
* Makefile.am (dist_pkgdata_DATA): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-06-29 14:27:22 +0200'>2019-06-29</span></td><td><a href='/guix/commit/etc/substitutes?id=3a8bfebed94ba295432da8304b7ffb4a611ef761'>etc: Remove hydra.gnu.org.pub key.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/substitutes/hydra.gnu.org.pub: Delete file.
* guix/self.scm (miscellaneous-files): Don't install it.
* Makefile.am (dist_pkgdata_DATA): Remove it.
* gnu/services/base.scm (%default-authorized-guix-keys): Likewise.
(hydra-key-authorization): Rename to…
(substitute-key-authorization): …this.  Adjust only call site.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-05-01 11:05:47 +0200'>2019-05-01</span></td><td><a href='/guix/commit/etc/substitutes?id=757e633d57a7b994759d69e41dd759a39f1a34ae'>build: Change default substitute server to "ci.guix.gnu.org".</a><span class='msg-avail'>...<span class='msg-tooltip'>* config-daemon.ac: Replace "ci.guix.info" with "ci.guix.gnu.org".
* doc/guix.texi (SUBSTITUTE-SERVER): Likewise.
* etc/substitutes/ci.guix.gnu.org.pub: New file.
* Makefile.am (dist_pkgdata_DATA): Add it.
* guix/scripts/build.scm (%default-log-urls): Update.
* guix/scripts/substitute.scm (%default-substitute-urls): Likewise.
* guix/store.scm (%default-substitute-urls): Likewise.
* guix/self.scm (miscellaneous-files): Add "ci.guix.gnu.org".
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-12-04 10:57:56 +0100'>2018-12-04</span></td><td><a href='/guix/commit/etc/substitutes?id=6a837b6062ab405f6ca6d9c0163836769098d89b'>etc: Add "ci.guix.info.pub" public key file.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/substitutes/ci.guix.info.pub: New file.
* Makefile.am (dist_pkgdata_DATA): Add it.
* guix/self.scm (miscellaneous-files): Add
"share/guix/ci.guix.info.pub".
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-11-06 00:04:11 +0100'>2018-11-06</span></td><td><a href='/guix/commit/etc/substitutes?id=aa919fbc890c5438166083f9ff02e4b1968a182b'>maint: Move substitute public keys to etc/substitutes.</a><span class='msg-avail'>...<span class='msg-tooltip'>* berlin.guixsd.org.pub, hydra.gnu.org.pub: Move to...
* etc/substitutes: ... here.  New directory.
* Makefile.am (dist_pkgdata_DATA): Adjust accordingly.
</span></span></td><td>Ludovic Courtès</td></tr>