[Pkg-kbd-devel] Bug#872623: kbd: setmetamode fails with StackSmashing detected

[alsauser at pragmasoft.com]

As a follow-up to my initial post ...

Obviously, changing the return statement in setmetamode.c is only
a "band-aid" that restores operation, but does nothing to correct
the underlying problem.

Upon closer examination, it appears that the KDGKBMETA IOCTL that
is called by setmetamode.c, is subsequently calling:
   put_user (<unsigned int>, (int __user*) arg);

Unfortunately, the argument (ometa) is only declared as "char" in
setmetamode.c.  So, in essence, we are asking the kernel to store
an <unsigned int> into a user space location that has only been
allocated as a "char".

I now believe that the appropriate correction is to change the
"char ometa, nmeta;" declaration in setmetamode.c to
"unsigned int ometa, nmeta;".  During my testing, this change
eliminated the StackSmashing detection and subsequent traceback.

If this problem and analysis is confirmed by other users, I would
hope that this fix could be propagated into a subsequent Stretch
update so as to restore operation of the setmetamode utility.