On Sat, 2005-12-03 at 01:38 +0000, Al Viro wrote:
> On Fri, Dec 02, 2005 at 08:09:59PM -0500, Steven Rostedt wrote:
> > > Secondly, they seem to use memcpy as opposed to using
> > > copy_to_user/copy_from_user which is also very
> > > dangerous.
> >
> > If they are grabbing data from user context into kernel (or vise versa)
> > that could easily cause an oops. Not to mention it is a security risk.
>
> Not to mention it simply won't work on a many platforms, no matter what...
Hmm, I've only worked with a few platforms (i386, x86_64, ppc, mips, and
a little arm but I don't remember that much). I believe that a memcpy
could work on all these platforms (error prone of course, but if the
memory is mapped its OK). When entering a system call, the kernel still
has access to the memory locations assigned to the user.
It's been a while since I had to deal with the semantics of
copy_to/from_user. So what platforms can not access a user space area
directly. Is there a special assembly command to use to copy from user?
I haven't dealt (yet) with the copy_user of x86_64. Is there a problem
when one tries to copy to/from a 32 bit address while in a 64 bit
address space?
Just curious, sorry for my ignorance here.
-- Steve
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]