Upstream-Status: Backport

CVE-2013-1752: Change use of readline in imaplib module to limit line length. Patch by Emil Lind.

Signed-off-by: Tudor Florea <tudor.florea@enea.com>

diff -r ce583eb0bec2 Lib/imaplib.py
--- a/Lib/imaplib.py	Thu Feb 21 20:17:54 2013 +0200
+++ b/Lib/imaplib.py	Tue Feb 26 22:36:52 2013 +0100
@@ -35,6 +35,15 @@
 IMAP4_SSL_PORT = 993
 AllowedVersions = ('IMAP4REV1', 'IMAP4')        # Most recent first
 
+# Maximal line length when calling readline(). This is to prevent
+# reading arbitrary length lines. RFC 3501 and 2060 (IMAP 4rev1)
+# don't specify a line length. RFC 2683 however suggests limiting client
+# command lines to 1000 octets and server command lines to 8000 octets.
+# We have selected 10000 for some extra margin and since that is supposedly
+# also what UW and Panda IMAP does.
+_MAXLINE = 10000
+
+
 #       Commands
 
 Commands = {
@@ -237,7 +246,10 @@
 
     def readline(self):
         """Read line from remote."""
-        return self.file.readline()
+        line = self.file.readline(_MAXLINE + 1)
+        if len(line) > _MAXLINE:
+            raise self.error("got more than %d bytes" % _MAXLINE) 
+        return line
 
 
     def send(self, data):