On Tue, Sep 19, 2017 at 03:02:22PM -0700, Kees Cook wrote:

On Mon, Sep 11, 2017 at 8:26 AM, Mark Salyzyn [off-list ref] wrote:

quoted

Make it possible to disable the kuser helpers by adding a KUSER_HELPERS
config option (enabled by default). When disabled, all kuser
helpers-related code is removed from the kernel and no mapping is done
at the fixed high address (0xffff0000); any attempt to use a kuser
helper from a 32-bit process will result in a segfault.

Signed-off-by: Mark Salyzyn <redacted>

v2:
- vectors_page and compat_vdso_spec as array of 2
- free sigpage if vectors allocation failed
- adjust makefile so one line for each of the assembler source modules
- split off assembler changes to a new previous patch in series to reduce churn
- modify slightly the feature documentation to reduce its reach
- modify slightly the feature documentation to rationalize the yes default.
- There are more ifdefs as a result of the rebase.

v3:
- rebase (minor conflicts)

This looks great to me. I'd love to see kuser helpers gone. :)

Catalin, Will, does this need anything else?

I haven't had chance to look at the patches yet (buried in other stuff), but
I aim to get to it in the next couple of weeks.

Will