Re: ASLRn't is still alive and well on x86 kernels, despite CVE-2024-26621 patch

["David A. Wheeler" <dwheeler () dwheeler com>]

Yves-Alexis Perez wrote in
> <6771f9536d49185fc8f1ea9905c13cf4dd8776d2.camel () debian org>:
> ...
> |mmap(NULL, 2097152, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 0, 0) = 0xf7df\
> |3000

On Jul 10, 2024, at 5:44 PM, Steffen Nurpmeso <steffen () sdaoden eu> wrote:
> I thought on Linux MAP_DENYWRITE is actually an ignored flag.

I believe you're correct, but I believe what Yves-Alexis Perez is showing is the
flags that are being *passed* to the kernel (whether or not they DO anything).
Which is why there's a proposal to *make* MAP_DENYWRITE do something in this case.

My plea is that if this DOES start doing something, PLEASE document that ASAP
(including a note that it USED to be ignored). I fear that this security property
might, on some platforms, depend on a quiet undocumented change.

--- David A. Wheeler