From: Gregory P. Smith <greg@krypto.org>
Date: Sat, 20 Jun 2020 19:15:03 +0000 (-0700)
Subject: bpo-41056: Fix a NULL pointer dereference on MemoryError within the ssl module. ... 
X-Git-Tag: v3.10.0a1~571
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=eb0d5c38de7f970d8cd8524f4163d831c7720f51;p=thirdparty%2FPython%2Fcpython.git

bpo-41056: Fix a NULL pointer dereference on MemoryError within the ssl module. (GH-21009)



Detected by Coverity.
---

diff --git a/Misc/NEWS.d/next/Library/2020-06-20-18-35-43.bpo-41056.Garcle.rst b/Misc/NEWS.d/next/Library/2020-06-20-18-35-43.bpo-41056.Garcle.rst
new file mode 100644
index 000000000000..1776f0d1cf8a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-06-20-18-35-43.bpo-41056.Garcle.rst
@@ -0,0 +1 @@
+Fix a NULL pointer dereference within the ssl module during a MemoryError in the keylog callback. (discovered by Coverity)
\ No newline at end of file
diff --git a/Modules/_ssl/debughelpers.c b/Modules/_ssl/debughelpers.c
index 858b3d7955c9..b840da2f663a 100644
--- a/Modules/_ssl/debughelpers.c
+++ b/Modules/_ssl/debughelpers.c
@@ -125,6 +125,12 @@ _PySSL_keylog_callback(const SSL *ssl, const char *line)
 
     threadstate = PyGILState_Ensure();
 
+    ssl_obj = (PySSLSocket *)SSL_get_app_data(ssl);
+    assert(PySSLSocket_Check(ssl_obj));
+    if (ssl_obj->ctx->keylog_bio == NULL) {
+        return;
+    }
+
     /* Allocate a static lock to synchronize writes to keylog file.
      * The lock is neither released on exit nor on fork(). The lock is
      * also shared between all SSLContexts although contexts may write to
@@ -141,12 +147,6 @@ _PySSL_keylog_callback(const SSL *ssl, const char *line)
         }
     }
 
-    ssl_obj = (PySSLSocket *)SSL_get_app_data(ssl);
-    assert(PySSLSocket_Check(ssl_obj));
-    if (ssl_obj->ctx->keylog_bio == NULL) {
-        return;
-    }
-
     PySSL_BEGIN_ALLOW_THREADS
     PyThread_acquire_lock(lock, 1);
     res = BIO_printf(ssl_obj->ctx->keylog_bio, "%s\n", line);