[Python-checkins] bpo-33706: Fix pymain_parse_cmdline_impl() (GH-7283)

[Victor Stinner]

https://github.com/python/cpython/commit/58d1683255abb0df4fc70960da6121aeaa41e1d1
commit: 58d1683255abb0df4fc70960da6121aeaa41e1d1
branch: master
author: Victor Stinner <vstinner at redhat.com>
committer: GitHub <noreply at github.com>
date: 2018-05-31T15:09:28+02:00
summary:

bpo-33706: Fix pymain_parse_cmdline_impl() (GH-7283)

Fix a crash in Python initialization when parsing the command line
options.

Fix memcpy() size parameter: previously, we read one wchar_t after
the end of _PyOS_optarg. Moreover, don't copy the trailingg NUL
character: we write it manually anyway.

Thanks Christoph Gohlke for the bug report and the fix!

files:
A Misc/NEWS.d/next/Core and Builtins/2018-05-31-14-50-04.bpo-33706.ztlH04.rst
M Modules/main.c

diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-05-31-14-50-04.bpo-33706.ztlH04.rst b/Misc/NEWS.d/next/Core and Builtins/2018-05-31-14-50-04.bpo-33706.ztlH04.rst
new file mode 100644
index 000000000000..d3b8477b2197
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-05-31-14-50-04.bpo-33706.ztlH04.rst	
@@ -0,0 +1,2 @@
+Fix a crash in Python initialization when parsing the command line options.
+Thanks Christoph Gohlke for the bug report and the fix!
diff --git a/Modules/main.c b/Modules/main.c
index 9cbb3f1ce003..286ad418fe13 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -761,7 +761,7 @@ pymain_parse_cmdline_impl(_PyMain *pymain, _Py_CommandLineDetails *cmdline)
                 pymain->err = _Py_INIT_NO_MEMORY();
                 return -1;
             }
-            memcpy(command, _PyOS_optarg, len * sizeof(wchar_t));
+            memcpy(command, _PyOS_optarg, (len - 2) * sizeof(wchar_t));
             command[len - 2] = '\n';
             command[len - 1] = 0;
             pymain->command = command;