From: Zackery Spytz <zspytz@gmail.com>
Date: Sat, 6 Oct 2018 17:41:45 +0000 (-0600)
Subject: bpo-34824: Fix a possible NULL pointer dereference in _ssl.c (GH-9606)
X-Git-Tag: v3.8.0a1~822
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=365ad2ead5bbaf7a3b18648ffa36e819559d3f75;p=python

bpo-34824: Fix a possible NULL pointer dereference in _ssl.c (GH-9606)



On failure, _PyBytes_Resize() will deallocate the bytes object and set
"result" to NULL.


https://bugs.python.org/issue34824
---

diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-09-27-11-10-02.bpo-34824.VLlCaU.rst b/Misc/NEWS.d/next/Core and Builtins/2018-09-27-11-10-02.bpo-34824.VLlCaU.rst
new file mode 100644
index 0000000000..fe95b8973c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-09-27-11-10-02.bpo-34824.VLlCaU.rst	
@@ -0,0 +1,2 @@
+Fix a possible null pointer dereference in Modules/_ssl.c. Patch by Zackery
+Spytz.
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 96bdac4491..93498f4756 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -4710,12 +4710,17 @@ _ssl_MemoryBIO_read_impl(PySSLMemoryBIO *self, int len)
         return result;
 
     nbytes = BIO_read(self->bio, PyBytes_AS_STRING(result), len);
-    /* There should never be any short reads but check anyway. */
-    if ((nbytes < len) && (_PyBytes_Resize(&result, len) < 0)) {
+    if (nbytes < 0) {
         Py_DECREF(result);
+        _setSSLError(NULL, 0, __FILE__, __LINE__);
         return NULL;
     }
 
+    /* There should never be any short reads but check anyway. */
+    if (nbytes < len) {
+        _PyBytes_Resize(&result, nbytes);
+    }
+
     return result;
 }