- Issue python#16038: CVE-2013-1752: ftplib: Limit amount of data read by

warsaw · warsaw · commit d6fddf3d15b5 · 2013-09-25T09:36:58.000-04:00
limiting the call to readline().  Original patch by Michał
  Jastrzębski and Giampaolo Rodola.

with test fixes by Serhiy Storchaka.
diff --git a/Lib/ftplib.py b/Lib/ftplib.py
@@ -54,6 +54,8 @@
 
 # The standard FTP server control port
 FTP_PORT = 21
+# The sizehint parameter passed to readline() calls
+MAXLINE = 8192
 
 
 # Exception raised when an error or invalid response is received
@@ -100,6 +102,7 @@ class FTP:
     debugging = 0
     host = ''
     port = FTP_PORT
+    maxline = MAXLINE
     sock = None
     file = None
     welcome = None
@@ -179,7 +182,9 @@ def putcmd(self, line):
     # Internal: return one line from the server, stripping CRLF.
     # Raise EOFError if the connection is closed
     def getline(self):
-        line = self.file.readline()
+        line = self.file.readline(self.maxline + 1)
+        if len(line) > self.maxline:
+            raise Error("got more than %d bytes" % self.maxline)
         if self.debugging > 1:
             print '*get*', self.sanitize(line)
         if not line: raise EOFError
@@ -421,7 +426,9 @@ def retrlines(self, cmd, callback = None):
         conn = self.transfercmd(cmd)
         fp = conn.makefile('rb')
         while 1:
-            line = fp.readline()
+            line = fp.readline(self.maxline + 1)
+            if len(line) > self.maxline:
+                raise Error("got more than %d bytes" % self.maxline)
             if self.debugging > 2: print '*retr*', repr(line)
             if not line:
                 break
@@ -473,7 +480,9 @@ def storlines(self, cmd, fp, callback=None):
         self.voidcmd('TYPE A')
         conn = self.transfercmd(cmd)
         while 1:
-            buf = fp.readline()
+            buf = fp.readline(self.maxline + 1)
+            if len(buf) > self.maxline:
+                raise Error("got more than %d bytes" % self.maxline)
             if not buf: break
             if buf[-2:] != CRLF:
                 if buf[-1] in CRLF: buf = buf[:-1]
diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
@@ -46,6 +46,7 @@ def __init__(self, conn):
         self.last_received_cmd = None
         self.last_received_data = ''
         self.next_response = ''
+        self.next_retr_data = RETR_DATA
         self.push('220 welcome')
 
     def collect_incoming_data(self, data):
@@ -162,7 +163,7 @@ def cmd_stor(self, arg):
 
     def cmd_retr(self, arg):
         self.push('125 retr ok')
-        self.dtp.push(RETR_DATA)
+        self.dtp.push(self.next_retr_data)
         self.dtp.close_when_done()
 
     def cmd_list(self, arg):
@@ -175,6 +176,11 @@ def cmd_nlst(self, arg):
         self.dtp.push(NLST_DATA)
         self.dtp.close_when_done()
 
+    def cmd_setlongretr(self, arg):
+        # For testing. Next RETR will return long line.
+        self.next_retr_data = 'x' * int(arg)
+        self.push('125 setlongretr ok')
+
 
 class DummyFTPServer(asyncore.dispatcher, threading.Thread):
 
@@ -362,6 +368,20 @@ def test_makepasv(self):
         # IPv4 is in use, just make sure send_epsv has not been used
         self.assertEqual(self.server.handler.last_received_cmd, 'pasv')
 
+    def test_line_too_long(self):
+        self.assertRaises(ftplib.Error, self.client.sendcmd,
+                          'x' * self.client.maxline * 2)
+
+    def test_retrlines_too_long(self):
+        self.client.sendcmd('SETLONGRETR %d' % (self.client.maxline * 2))
+        received = []
+        self.assertRaises(ftplib.Error,
+                          self.client.retrlines, 'retr', received.append)
+
+    def test_storlines_too_long(self):
+        f = StringIO.StringIO('x' * self.client.maxline * 2)
+        self.assertRaises(ftplib.Error, self.client.storlines, 'stor', f)
+
 
 class TestIPv6Environment(TestCase):
 
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -13,6 +13,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #16038: CVE-2013-1752: ftplib: Limit amount of data read by
+  limiting the call to readline().  Original patch by Michał
+  Jastrzębski and Giampaolo Rodola.
+
 - Issue #16039: CVE-2013-1752: Change use of readline in imaplib module to
   limit line length.  Patch by Emil Lind.
 
