From: Nadeem Vawda <nadeem.vawda@gmail.com>
Date: Sun, 28 Aug 2011 09:26:46 +0000 (+0200)
Subject: Issue #12839: Fix crash in zlib module due to version mismatch.
X-Git-Tag: v3.2.2~22
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=97d67924e3a3ac1bbe07d6abc02c233a330013f1;p=thirdparty%2FPython%2Fcpython.git

Issue #12839: Fix crash in zlib module due to version mismatch.

If the version of zlib used to compile the zlib module is incompatible
with the one that is actually linked in, then calls into zlib will fail.
This can leave attributes of the z_stream uninitialized, so we must take
care to avoid segfaulting by trying to use an invalid pointer.

Fix by Richard M. Tew.
---

diff --git a/Misc/ACKS b/Misc/ACKS
index d345e54ef9d1..add8c617a7ff 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -873,6 +873,7 @@ Monty Taylor
 Amy Taylor
 Anatoly Techtonik
 Mikhail Terekhov
+Richard M. Tew
 Tobias Thelen
 James Thomas
 Robin Thomas
diff --git a/Misc/NEWS b/Misc/NEWS
index 48ef326d56e3..86eea69a3f61 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -17,6 +17,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #12839: Fix crash in zlib module due to version mismatch.
+  Fix by Richard M. Tew.
+
+
 
 What's New in Python 3.2.2 release candidate 1?
 ===============================================
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index ba0e59ce0641..a1e605b3d2be 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -52,7 +52,13 @@ typedef struct
 static void
 zlib_error(z_stream zst, int err, char *msg)
 {
-    const char *zmsg = zst.msg;
+    const char *zmsg = Z_NULL;
+    /* In case of a version mismatch, zst.msg won't be initialized.
+       Check for this case first, before looking at zst.msg. */
+    if (err == Z_VERSION_ERROR)
+        zmsg = "library version mismatch";
+    if (zmsg == Z_NULL)
+        zmsg = zst.msg;
     if (zmsg == Z_NULL) {
         switch (err) {
         case Z_BUF_ERROR: