[PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive()

[Jason A. Donenfeld]

On Tue, Jun 16, 2020 at 12:54 PM Joe Perches <joe at perches.com> wrote:
>
> On Mon, 2020-06-15 at 21:57 -0400, Waiman Long wrote:
> >  v4:
> >   - Break out the memzero_explicit() change as suggested by Dan Carpenter
> >     so that it can be backported to stable.
> >   - Drop the "crypto: Remove unnecessary memzero_explicit()" patch for
> >     now as there can be a bit more discussion on what is best. It will be
> >     introduced as a separate patch later on after this one is merged.
>
> To this larger audience and last week without reply:
> https://lore.kernel.org/lkml/573b3fbd5927c643920e1364230c296b23e7584d.camel@perches.com/
>
> Are there _any_ fastpath uses of kfree or vfree?

The networking stack has various places where there will be a quick
kmalloc followed by a kfree for an incoming or outgoing packet. One
place that comes to mind would be esp_alloc_tmp, which does a quick
allocation of some temporary kmalloc memory, processes some packet
things inside of that, and then frees it, sometimes in the same
function, and sometimes later in an async callback. I don't know how
"fastpath" you consider this, but usually packet processing is
something people want to do with minimal overhead, considering how
fast NICs are these days.