[prev in list] [next in list] [prev in thread] [next in thread] 

List:       mythtv-dev
Subject:    Re: [mythtv] VideoOut Priority
From:       Simon Wilkinson <simon () sxw ! org ! uk>
Date:       2004-01-30 23:24:42
Message-ID: 401AE7BA.4060505 () sxw ! org ! uk
[Download RAW message or body]

Kenneth Aafløy wrote:

> And you can run MythTV with a non root user if you assign the correct 
> permissions to /dev/mem (untested - but all reasonable logic tells me that it 
> should work), but that's another security hole (not that it matters on a 
> frontend).

No, you can't.

The problem is that ddmpeg calls ioperm() and iopl() to gain permission 
for a later call to inb(). The ioperm() and iopl() fail when not run as 
root, but the exit code isn't checked. This means that when inb() is 
called, it seg faults, as indictated in its man page:

  You  use ioperm(2) or alternatively iopl(2) to tell the kernel to allow
  the user space application to access the I/O ports in question. Failure
  to  do this will cause the application to receive a segmentation fault.

Cheers,

Simon.




[prev in list] [next in list] [prev in thread] [next in thread]