Fix CVE-2017-16844:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-16844
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=876511

Patch copied from Debian procmail package 3.22-26:

http://http.debian.net/debian/pool/main/p/procmail/procmail_3.22-26.debian.tar.xz

From: Santiago Vila <sanvila@debian.org>
Subject: Fix heap-based buffer overflow in loadbuf()
Bug-Debian: http://bugs.debian.org/876511
X-Debian-version: 3.22-26

--- a/src/formisc.c
+++ b/src/formisc.c
@@ -103,7 +103,7 @@
 }
 							    /* append to buf */
 void loadbuf(text,len)const char*const text;const size_t len;
-{ if(buffilled+len>buflen)			  /* buf can't hold the text */
+{ while(buffilled+len>buflen)			  /* buf can't hold the text */
      buf=realloc(buf,buflen+=Bsize);
   tmemmove(buf+buffilled,text,len);buffilled+=len;
 }
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<tr><td><span title='2023-12-11 23:18:53 +0100'>2023-12-11</span></td><td><a href='/guix/commit/nix/libstore/worker-protocol.hh?id=1e47148f46e31eb99ce8ec7bc12232cf50d0ebec'>daemon: Implement ‘substitute-urls’ RPC.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>