Re: [PATCH 1/2] x86: Increase brk randomness entropy on x86_64

[Jiri Kosina]

On Fri, 16 Feb 2024, Kees Cook wrote:

> In commit c1d171a00294 ("x86: randomize brk"), arch_randomize_brk() was
> defined to use a 32MB range (13 bits of entropy), but was never increased
> when moving to 64-bit. The default arch_randomize_brk() uses 32MB for
> 32-bit tasks, and 1GB (18 bits of entropy) for 64-bit tasks. Update
> x86_64 to match the entropy used by arm64 and other 64-bit architectures.
> 
> Reported-by: y0un9n132@xxxxxxxxx
> Closes: https://lore.kernel.org/linux-hardening/CA+2EKTVLvc8hDZc+2Yhwmus=dzOUG5E4gV7ayCbu0MPJTZzWkw@xxxxxxxxxxxxxx/
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Wow, this is a pretty aged code indeed.

	Acked-by: Jiri Kosina <jkosina@xxxxxxxx>

Thanks,

-- 
Jiri Kosina
SUSE Labs