[3.13] Revert "gh-119452: Fix a potential virtual memory allocation denial of service in http.server (GH-119455) (GH-142130)" (#142185)

Revert "[3.13] gh-119452: Fix a potential virtual memory allocation denial of service in http.server (GH-119455) (GH-142130)"

This reverts commit 6c922bbe28.

Lib/http/server.py

@@ -127,10 +127,6 @@
 
 DEFAULT_ERROR_CONTENT_TYPE = "text/html;charset=utf-8"
 
-# Data larger than this will be read in chunks, to prevent extreme
-# overallocation.
-_MIN_READ_BUF_SIZE = 1 << 20
-
 class HTTPServer(socketserver.TCPServer):
 
     allow_reuse_address = 1    # Seems to make sense in testing environment
@@ -1238,16 +1234,7 @@ def run_cgi(self):
                                  env = env
                                  )
             if self.command.lower() == "post" and nbytes > 0:
-                cursize = 0
-                data = self.rfile.read(min(nbytes, _MIN_READ_BUF_SIZE))
-                while (len(data) < nbytes and len(data) != cursize and
-                       select.select([self.rfile._sock], [], [], 0)[0]):
-                    cursize = len(data)
-                    # This is a geometric increase in read size (never more
-                    # than doubling our the current length of data per loop
-                    # iteration).
-                    delta = min(cursize, nbytes - cursize)
-                    data += self.rfile.read(delta)
+                data = self.rfile.read(nbytes)
             else:
                 data = None
             # throw away additional data [see bug #427345]

Lib/test/test_httpservers.py

@@ -802,20 +802,6 @@ def test_path_without_leading_slash(self):
 print("</pre>")
 """
 
-cgi_file7 = """\
-#!%s
-import os
-import sys
-
-print("Content-type: text/plain")
-print()
-
-content_length = int(os.environ["CONTENT_LENGTH"])
-body = sys.stdin.buffer.read(content_length)
-
-print(f"{content_length} {len(body)}")
-"""
-
 
 @unittest.skipIf(hasattr(os, 'geteuid') and os.geteuid() == 0,
         "This test can't be run reliably as root (issue #13308).")
@@ -855,8 +841,6 @@ def setUp(self):
         self.file3_path = None
         self.file4_path = None
         self.file5_path = None
-        self.file6_path = None
-        self.file7_path = None
 
         # The shebang line should be pure ASCII: use symlink if possible.
         # See issue #7668.
@@ -911,11 +895,6 @@ def setUp(self):
             file6.write(cgi_file6 % self.pythonexe)
         os.chmod(self.file6_path, 0o777)
 
-        self.file7_path = os.path.join(self.cgi_dir, 'file7.py')
-        with open(self.file7_path, 'w', encoding='utf-8') as file7:
-            file7.write(cgi_file7 % self.pythonexe)
-        os.chmod(self.file7_path, 0o777)
-
         os.chdir(self.parent_dir)
 
     def tearDown(self):
@@ -938,8 +917,6 @@ def tearDown(self):
                 os.remove(self.file5_path)
             if self.file6_path:
                 os.remove(self.file6_path)
-            if self.file7_path:
-                os.remove(self.file7_path)
             os.rmdir(self.cgi_child_dir)
             os.rmdir(self.cgi_dir)
             os.rmdir(self.cgi_dir_in_sub_dir)
@@ -1012,21 +989,6 @@ def test_post(self):
 
         self.assertEqual(res.read(), b'1, python, 123456' + self.linesep)
 
-    def test_large_content_length(self):
-        for w in range(15, 25):
-            size = 1 << w
-            body = b'X' * size
-            headers = {'Content-Length' : str(size)}
-            res = self.request('/cgi-bin/file7.py', 'POST', body, headers)
-            self.assertEqual(res.read(), b'%d %d' % (size, size) + self.linesep)
-
-    def test_large_content_length_truncated(self):
-        for w in range(18, 65):
-            size = 1 << w
-            headers = {'Content-Length' : str(size)}
-            res = self.request('/cgi-bin/file1.py', 'POST', b'x', headers)
-            self.assertEqual(res.read(), b'Hello World' + self.linesep)
-
     def test_invaliduri(self):
         res = self.request('/cgi-bin/invalid')
         res.read()

Misc/NEWS.d/next/Security/2024-05-23-11-44-41.gh-issue-119452.PRfsSv.rst

@@ -1,5 +0,0 @@
-Fix a potential memory denial of service in the :mod:`http.server` module.
-When a malicious user is connected to the CGI server on Windows, it could cause
-an arbitrary amount of memory to be allocated.
-This could have led to symptoms including a :exc:`MemoryError`, swapping, out
-of memory (OOM) killed processes or containers, or even system crashes.