Fedora Kernel: Strict user copy checks: Disabled

[Paul Bolle]

On Wed, 2013-07-17 at 15:25 -0400, Dave Jones wrote:
> On Tue, Jul 16, 2013 at 03:39:35PM +0200, Reindl Harald wrote:
>  > is there a strong performance-wise reason for
>  > "Strict user copy checks: Disabled" - IMHO if
>  > something may make things more secure while not
>  > have a dramatically performance impact security
>  > in doubt should go first

Are that the checks enabled by CONFIG_DEBUG_STRICT_USER_COPY_CHECKS? If
so, they don't do anything on x86_64 (which Harald seems to be using),
do they?

And please note that on x86_32 one will still see compiler warnings if
that Kconfig symbol is not set.

And also note that recently (I think since v3.10, but I haven't checked)
actually no copy_from_user() related warnings show up when building for
x86_32 and using Fedora-based .config. At least, they don't show up
anymore when I build locally. I'm not sure what caused that.


Paul Bolle