Re: Security question: "Text file busy" overwriting executables but

Alan Cox
2001-10-04T20:35:00Z

> On Thu, 4 Oct 2001, Linus Torvalds wrote:
>
> > The reason the kernel refuses to honour it, is that MAP_DENYWRITE is an
> > excellent DoS-vehicle - you just mmap("/etc/passwd") with MAP_DENYWRITE,
> > and even root cannot write to it.. Vary nasty.
>
> <nit>
> I _really_ doubt that something does write() on /etc/passwd. Create a
> file and rename it over the thing - sure, but that's it.
> </nit>

The MAP_DENYWRITE rule was added a long time ago because people found actual
workable DoS attacks