On Thu, Jan 19, 2023 at 12:08 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> >
> > What do you suggest?
> > I frankly don't see other options other than done in this patch,
> > though it's not great.
> > Happy to be proven otherwise.
>
> Matthew, do you have any thoughts on dealing with this? Can we use a
> counter instead of a spin lock?
Have you consider using pagefault_disabled() instead of in_interrupt()?
spin_trylock() and if (pagefault_disabled()) out ?
or
diff --git a/mm/usercopy.c b/mm/usercopy.c
index 4c3164beacec..83c164aba6e0 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -173,7 +173,7 @@ static inline void check_heap_object(const void
*ptr, unsigned long n,
return;
}
- if (is_vmalloc_addr(ptr)) {
+ if (is_vmalloc_addr(ptr) && !pagefault_disabled()) {
struct vmap_area *area = find_vmap_area(addr);
effectively gutting that part of check for *_nofault() and *_nmi() ?
