[3.6] bpo-41004: Resolve hash collisions for IPv4Interface and IPv6Interface (GH...

CVE-2020-14422
The __hash__() methods of classes IPv4Interface and IPv6Interface had issue
of generating constant hash values of 32 and 128 respectively causing hash collisions.
The fix uses the hash() function to generate hash values for the objects
instead of XOR operation
(cherry picked from commit b30ee26e366bf509b7538d79bfec6c6d38d53f28)

Co-authored-by: Ravi Teja P <rvteja92@gmail.com>
Signed-off-by: Tapas Kundu <tkundu@vmware.com>

diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index 583f02ad5427529a998d2deba8f69dce9212bcb0..98492136ca5f4011a4998578029cd0b16fbcf333 100644 (file)
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -1418,7 +1418,7 @@ class IPv4Interface(IPv4Address):
             return False
 
     def __hash__(self):
-        return self._ip ^ self._prefixlen ^ int(self.network.network_address)
+        return hash((self._ip, self._prefixlen, int(self.network.network_address)))
 
     __reduce__ = _IPAddressBase.__reduce__
 
@@ -2092,7 +2092,7 @@ class IPv6Interface(IPv6Address):
             return False
 
     def __hash__(self):
-        return self._ip ^ self._prefixlen ^ int(self.network.network_address)
+        return hash((self._ip, self._prefixlen, int(self.network.network_address)))
 
     __reduce__ = _IPAddressBase.__reduce__
 

diff --git a/Lib/test/test_ipaddress.py b/Lib/test/test_ipaddress.py
index 1cef4217bc88344e51ada60cae662a4879d5546b..7de444af4aa57c2c0cfdd58edc4af840484dfb7c 100644 (file)
--- a/Lib/test/test_ipaddress.py
+++ b/Lib/test/test_ipaddress.py
@@ -1990,6 +1990,17 @@ class IpaddrUnitTest(unittest.TestCase):
                          sixtofouraddr.sixtofour)
         self.assertFalse(bad_addr.sixtofour)
 
+    # issue41004 Hash collisions in IPv4Interface and IPv6Interface
+    def testV4HashIsNotConstant(self):
+        ipv4_address1 = ipaddress.IPv4Interface("1.2.3.4")
+        ipv4_address2 = ipaddress.IPv4Interface("2.3.4.5")
+        self.assertNotEqual(ipv4_address1.__hash__(), ipv4_address2.__hash__())
+
+    # issue41004 Hash collisions in IPv4Interface and IPv6Interface
+    def testV6HashIsNotConstant(self):
+        ipv6_address1 = ipaddress.IPv6Interface("2001:658:22a:cafe:200:0:0:1")
+        ipv6_address2 = ipaddress.IPv6Interface("2001:658:22a:cafe:200:0:0:2")
+        self.assertNotEqual(ipv6_address1.__hash__(), ipv6_address2.__hash__())
 
 if __name__ == '__main__':
     unittest.main()

diff --git a/Misc/NEWS.d/next/Security/2020-06-29-16-02-29.bpo-41004.ovF0KZ.rst b/Misc/NEWS.d/next/Security/2020-06-29-16-02-29.bpo-41004.ovF0KZ.rst
new file mode 100644 (file)
index 0000000..f5a9db5
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2020-06-29-16-02-29.bpo-41004.ovF0KZ.rst
@@ -0,0 +1 @@
+CVE-2020-14422: The __hash__() methods of  ipaddress.IPv4Interface and ipaddress.IPv6Interface incorrectly generated constant hash values of 32 and 128 respectively. This resulted in always causing hash collisions. The fix uses hash() to generate hash values for the tuple of (address, mask length, network address).