Re: [GIT PULL] MM updates for 6.1-rc1

[Josh Poimboeuf]

On Tue, Oct 11, 2022 at 10:24:27AM +0200, Peter Zijlstra wrote:
> On Mon, Oct 10, 2022 at 06:20:00PM -0700, Linus Torvalds wrote:
> > The other thing I notice from just doing a build is that I now get
> > 
> >    vmlinux.o: warning: objtool: kasan_report+0x12: call to
> > stackleak_track_stack() with UACCESS enabled
> 
> So kasan_report() is already marked as being special; and it does the
> mandatory user_access_save() / user_access_restore() things to fix it
> up.
> 
> But it looks like kasan code itself is now getting instrumented by the
> stackleak stuff and that inserts a call outside of the
> user_access_save()/restore() thing, and *that* is getting flagged.
> 
> Looking at mm/kasan/Makefile it disables a lot of the instrumentation,
> but perhaps not enough?

I can recreate, but weirdly the below doesn't seem to fix it.

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index d4837bff3b60..a41cf1235032 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 KASAN_SANITIZE := n
+KMSAN_SANITIZE := n
 UBSAN_SANITIZE := n
 KCOV_INSTRUMENT := n