[Python-checkins] cpython (2.7): Issue #12839: Fix crash in zlib module due to version mismatch.

[nadeem.vawda]

http://hg.python.org/cpython/rev/ba5000307b5d
changeset:   72110:ba5000307b5d
branch:      2.7
parent:      72105:a355731f105c
user:        Nadeem Vawda <nadeem.vawda at gmail.com>
date:        Sun Aug 28 11:23:57 2011 +0200
summary:
  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.

files:
  Misc/ACKS            |  1 +
  Misc/NEWS            |  3 +++
  Modules/zlibmodule.c |  8 +++++++-
  3 files changed, 11 insertions(+), 1 deletions(-)


diff --git a/Misc/ACKS b/Misc/ACKS
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -813,6 +813,7 @@
 Amy Taylor
 Anatoly Techtonik
 Mikhail Terekhov
+Richard M. Tew
 Tobias Thelen
 James Thomas
 Robin Thomas
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -40,6 +40,9 @@
 Library
 -------
 
+- Issue #12839: Fix crash in zlib module due to version mismatch.
+  Fix by Richard M. Tew.
+
 - Issue #12786: Set communication pipes used by subprocess.Popen CLOEXEC to
   avoid them being inherited by other subprocesses.
 
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -72,7 +72,13 @@
 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:

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