# HG changeset patch
# Parent  e0761e817deb20ccd8e6612f11ed79eb4caee3be
Issue #nnnnn: Avoid zero-length memcpy() calls with null source pointers

diff -r e0761e817deb Misc/NEWS
--- a/Misc/NEWS	Tue Jul 19 02:50:51 2016 +0000
+++ b/Misc/NEWS	Tue Jul 19 02:56:44 2016 +0000
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #nnnnn: Avoid zero-length memcpy() etc calls with null source
+  pointers.
+
 - Issue #27507: Add integer overflow check in bytearray.extend().  Patch by
   Xiang Zhang.
 
diff -r e0761e817deb Modules/_ctypes/_ctypes.c
--- a/Modules/_ctypes/_ctypes.c	Tue Jul 19 02:50:51 2016 +0000
+++ b/Modules/_ctypes/_ctypes.c	Tue Jul 19 02:56:44 2016 +0000
@@ -1381,8 +1381,10 @@
         goto error;
     }
     stgdict->shape[0] = length;
-    memmove(&stgdict->shape[1], itemdict->shape,
-        sizeof(Py_ssize_t) * (stgdict->ndim - 1));
+    if (stgdict->ndim > 1) {
+        memmove(&stgdict->shape[1], itemdict->shape,
+            sizeof(Py_ssize_t) * (stgdict->ndim - 1));
+    }
 
     itemsize = itemdict->size;
     if (length * itemsize < 0) {
diff -r e0761e817deb Modules/_ctypes/stgdict.c
--- a/Modules/_ctypes/stgdict.c	Tue Jul 19 02:50:51 2016 +0000
+++ b/Modules/_ctypes/stgdict.c	Tue Jul 19 02:56:44 2016 +0000
@@ -391,9 +391,11 @@
         }
         memset(stgdict->ffi_type_pointer.elements, 0,
                sizeof(ffi_type *) * (basedict->length + len + 1));
-        memcpy(stgdict->ffi_type_pointer.elements,
-               basedict->ffi_type_pointer.elements,
-               sizeof(ffi_type *) * (basedict->length));
+        if (basedict->length > 0) {
+            memcpy(stgdict->ffi_type_pointer.elements,
+                   basedict->ffi_type_pointer.elements,
+                   sizeof(ffi_type *) * (basedict->length));
+        }
         ffi_ofs = basedict->length;
     } else {
         offset = 0;
diff -r e0761e817deb Modules/hashtable.c
--- a/Modules/hashtable.c	Tue Jul 19 02:50:51 2016 +0000
+++ b/Modules/hashtable.c	Tue Jul 19 02:56:44 2016 +0000
@@ -71,8 +71,10 @@
 #define ENTRY_WRITE_PDATA(TABLE, ENTRY, DATA_SIZE, PDATA) \
     do { \
         assert((DATA_SIZE) == (TABLE)->data_size); \
-        Py_MEMCPY((void *)_Py_HASHTABLE_ENTRY_PDATA((TABLE), (ENTRY)), \
-                  (PDATA), (DATA_SIZE)); \
+        if ((DATA_SIZE) > 0) { \
+            Py_MEMCPY((void *)_Py_HASHTABLE_ENTRY_PDATA((TABLE), (ENTRY)), \
+                      (PDATA), (DATA_SIZE)); \
+        } \
     } while (0)
 
 /* Forward declaration */
diff -r e0761e817deb Objects/listobject.c
--- a/Objects/listobject.c	Tue Jul 19 02:50:51 2016 +0000
+++ b/Objects/listobject.c	Tue Jul 19 02:56:44 2016 +0000
@@ -648,7 +648,9 @@
             goto Error;
         }
     }
-    memcpy(recycle, &item[ilow], s);
+    if (s > 0) {
+        memcpy(recycle, &item[ilow], s);
+    }
 
     if (d < 0) { /* Delete -d items */
         Py_ssize_t tail;