Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1628455

Re: [PATCH 2/5] KEYS: user_defined: sanitize key payloads

Show all headers | View raw

On Fri, Apr 21, 2017 at 02:57:17PM +0100, David Howells wrote:
> Eric Biggers <ebiggers3@gmail.com> wrote:
> 
> > -		kfree_rcu(zap, rcu);
> > +		call_rcu(&zap->rcu, user_free_payload_rcu);
> 
> Add kzfree_rcu()?
> 
> David

We could, but it's not trivial because the way kfree_rcu() works is to store the
offset of the rcu_head as the callback function, then have a special case in RCU
reclaim that recognizes "function pointers" with value < 4096 and call kfree()
rather than the function.  To support kzfree_rcu() we'd need to reserve another
4096 bytes of the address space (maybe at the end?), then check for the special
kzfree value on every RCU reclaim.  Or equivalently it could be a flag.  It's
possible, but it may be best to just use a custom callback for now.  Then if it
can be shown later that there are a lot of users who would like a
"kzfree_rcu()", it can be added.

- Eric

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/5] KEYS: sanitize key payloads Eric Biggers <ebiggers3@gmail.com> - 2017-04-21 10:40 +0200
  [PATCH 1/5] KEYS: sanitize add_key() and keyctl() key payloads Eric Biggers <ebiggers3@gmail.com> - 2017-04-21 10:40 +0200
  [PATCH 4/5] KEYS: trusted: sanitize all key material Eric Biggers <ebiggers3@gmail.com> - 2017-04-21 10:40 +0200
  [PATCH 2/5] KEYS: user_defined: sanitize key payloads Eric Biggers <ebiggers3@gmail.com> - 2017-04-21 10:40 +0200
    Re: [PATCH 2/5] KEYS: user_defined: sanitize key payloads David Howells <dhowells@redhat.com> - 2017-04-21 16:00 +0200
      Re: [PATCH 2/5] KEYS: user_defined: sanitize key payloads Eric Biggers <ebiggers3@gmail.com> - 2017-04-21 20:40 +0200
        Re: [PATCH 2/5] KEYS: user_defined: sanitize key payloads David Howells <dhowells@redhat.com> - 2017-04-24 16:20 +0200

csiph-web