Re: [Valgrind-users] another 'cannot enable executable stack as shared object requires: Invalid argument'

[John R. <jr...@Bi...>]

> $ valgrind --tool=memcheck --log-file=log --trace-syscalls=yes \
>     python -c 'import ctypes'
> 
> Traceback (most recent call last):
>   File "<string>", line 1, in ?
>   File "ctypes/__init__.py", line 13, in ?
>     from _ctypes import Union, Structure, Array
> ImportError: ./_ctypes.so: cannot enable executable stack as shared 
> object requires: Invalid argument

    $ execstack --query ./_ctypes.so $( which valgrind )
Note that _ctypes.so probably says '?' ["don't know"]
and valgrind probably says '-' ["executable stack not required"].

    $ readelf --program-headers ./_ctypes.so
    $ readelf --program-headers $( which valgrind )
Look at the GNU_STACK line.  _ctypes.so probably has none at all,
while valrind probably has one that says "RW-" ["executable stack
not required" because no 'X' is present].

So, valgrind forgot to put "-W,-z,execstack" in its static link command
so as to be usable when an old .so is invoked on a new system where
dlopen [and ld-linux.so.2, both of which are components of glibc]
and the Linux kernel enforce non-executable stacks.

Also, _ctype.so forgot to put "-W,-z,noexecstack" in its static link
command, so as to be usable on systems that prefer to enforce non-
executable stacks.

It might be possible to achieve a "quick fix" via
    $ execstack --clear-execstack ./_ctype.so
[above is preferable] _or_ via [below is last resort]
    $ execstack --set-execstack $( which valgrind )
assuming you have the necessary filesystem permissions.

-- 
John Reiser, jr...@Bi...