Re: Security fix for remapping of page 0 (was [PATCH] Change ZERO_SIZE_PTR to point at unmapped space)

Christoph Lameter
2009-06-03T19:42:35Z

On Wed, 3 Jun 2009, Eric Paris wrote:

> NAK with SELinux on you now need both the SELinux mmap_zero
> permission and the CAP_SYS_RAWIO permission. Previously you only
> needed one or the other, depending on which was the predominant
> LSM.....

CAP_SYS_RAWIO is checked so you only need to check for mmap_zero in
SELinux.

> Even if you want to argue that I have to take CAP_SYS_RAWIO in the
> SELinux case what about all the other places? do_mremap? do_brk?
> expand_downwards?

brk(0) would free up all the code? The others could be added.