commit 51b36ed96d29c9440fbca18fb0c9e3087f763da5
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Fri Jul 10 03:18:45 2020 -0700
committer GitHub <noreply@github.com> Fri Jul 10 03:18:45 2020 -0700
tree 9292654309c41e429358f2ab1c1bc7c0b50a70c4
parent fd27fb7f3dd157294f05bb060f7efd243732ab2d

bpo-41175: Guard against a NULL pointer dereference within bytearrayobject (GH-21240)


The issue is triggered by the bytearray() + bytearray() operation.

Detected by GCC 10 static analysis tool.
(cherry picked from commit 61fc23ca106bc82955b0e59d1ab42285b94899e2)

Co-authored-by: stratakis <cstratak@redhat.com>

Objects/bytearrayobject.c

diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 5a803be..97d7796 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -273,7 +273,9 @@
 
     result = (PyByteArrayObject *) \
         PyByteArray_FromStringAndSize(NULL, va.len + vb.len);
-    if (result != NULL) {
+    // result->ob_bytes is NULL if result is an empty string:
+    // if va.len + vb.len equals zero.
+    if (result != NULL && result->ob_bytes != NULL) {
         memcpy(result->ob_bytes, va.buf, va.len);
         memcpy(result->ob_bytes + va.len, vb.buf, vb.len);
     }