Currently this Python program triggers a segmentation fault in
libselinux SWIG wrapper:
import selinux
selinux.get_ordered_context_list()
gdb shows that the segmentation fault occurs when freeing some memory:
Reading symbols from python...(no debugging symbols found)...done.
Starting program: /usr/bin/python -c import\
selinux\;selinux.get_ordered_context_list\(\)
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff789a304 in free () from /usr/lib/libc.so.6
(gdb) bt
#0 0x00007ffff789a304 in free () from /usr/lib/libc.so.6
#1 0x00007ffff6011499 in freeconary (con=0x7ffff6ac5d00) at
freeconary.c:14
#2 0x00007ffff6296899 in _wrap_get_ordered_context_list
(self=<optimized out>, args=<optimized out>) at
selinuxswig_wrap.c:6185
#3 0x00007ffff741891f in _PyCFunction_FastCallDict () from
/usr/lib/libpython3.6m.so.1.0
...
SWIG generated the following code for _wrap_get_ordered_context_list():
char ***arg3 = (char ***) 0 ;
char **temp3 ;
arg3 = &temp3;
if (!PyArg_ParseTuple(args, "OO:get_ordered_context_list",&obj0,&obj1))
SWIG_fail;
/* ... */
fail:
if (*arg3) freeconary(*arg3);
If PyArg_ParseTuple fails, freeconary() is called on the value of
"temp3", which has not been initialized. Fix this by initializing temp
to NULL in the SWIG template.
A similar issue exists with security_get_boolean_names(). Fix it too.
This issue has been found using clang's static analyzer, on a system
which uses SWIG 3.0.12.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
ded385d377