Address review comments.

Author: serhiy-storchaka

Lib/http/server.py

@@ -136,7 +136,7 @@
 
 # Data larger than this will be read in chunks, to prevent extreme
 # overallocation.
-SAFE_BUF_SIZE = 1 << 20
+_MIN_READ_BUF_SIZE = 1 << 20
 
 class HTTPServer(socketserver.TCPServer):
 
@@ -1289,10 +1289,13 @@ def run_cgi(self):
                                  )
             if self.command.lower() == "post" and nbytes > 0:
                 cursize = 0
-                data = self.rfile.read(min(nbytes, SAFE_BUF_SIZE))
+                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)
             else:

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

@@ -1,6 +1,5 @@
-Fix a potential denial of service in the :mod:`http.server` module.
+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.
-In best case this could lead to a :exc:`MemoryError` or other process crash.
-In worst case it could lead to swapping which would dramatically slow down the
-whole system and make it less responcible.
+This could have led to symptoms including a :exc:`MemoryError`, swapping, out
+of memory (OOM) killed processes or containers, or even system crashes.