[Python-checkins] cpython (merge 3.3 -> default): Issue #16411: Fix a bug where zlib.decompressobj().flush() might try to access

[nadeem.vawda]

http://hg.python.org/cpython/rev/d63c751e9f01
changeset:   80356:d63c751e9f01
parent:      80352:4440e45c10f9
parent:      80355:a7934fe2927e
user:        Nadeem Vawda <nadeem.vawda at gmail.com>
date:        Sun Nov 11 03:19:49 2012 +0100
summary:
  Issue #16411: Fix a bug where zlib.decompressobj().flush() might try to access previously-freed memory.

Patch by Serhiy Storchaka.

files:
  Lib/test/test_zlib.py |  12 ++++++++++++
  Misc/NEWS             |   3 +++
  Modules/zlibmodule.c  |   2 ++
  3 files changed, 17 insertions(+), 0 deletions(-)


diff --git a/Lib/test/test_zlib.py b/Lib/test/test_zlib.py
--- a/Lib/test/test_zlib.py
+++ b/Lib/test/test_zlib.py
@@ -513,6 +513,18 @@
                 self.assertEqual(dco.unconsumed_tail, b'')
                 self.assertEqual(dco.unused_data, remainder)
 
+    def test_flush_with_freed_input(self):
+        # Issue #16411: decompressor accesses input to last decompress() call
+        # in flush(), even if this object has been freed in the meanwhile.
+        input1 = b'abcdefghijklmnopqrstuvwxyz'
+        input2 = b'QWERTYUIOPASDFGHJKLZXCVBNM'
+        data = zlib.compress(input1)
+        dco = zlib.decompressobj()
+        dco.decompress(data, 1)
+        del data
+        data = zlib.compress(input2)
+        self.assertEqual(dco.flush(), input1[1:])
+
     if hasattr(zlib.compressobj(), "copy"):
         def test_compresscopy(self):
             # Test copying a compression object
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -113,6 +113,9 @@
 Library
 -------
 
+- Issue #16411: Fix a bug where zlib.decompressobj().flush() might try to access
+  previously-freed memory. Patch by Serhiy Storchaka.
+
 - Issue #16357: fix calling accept() on a SSLSocket created through
   SSLContext.wrap_socket().  Original patch by Jeff McNeil.
 
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -975,6 +975,8 @@
     ENTER_ZLIB(self);
 
     start_total_out = self->zst.total_out;
+    self->zst.avail_in = PyBytes_GET_SIZE(self->unconsumed_tail);
+    self->zst.next_in = (Byte *)PyBytes_AS_STRING(self->unconsumed_tail);
     self->zst.avail_out = length;
     self->zst.next_out = (Byte *)PyBytes_AS_STRING(retval);
 

-- 
Repository URL: http://hg.python.org/cpython