From: Eric Biggers <ebiggers3@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH 2/5] KEYS: user_defined: sanitize key payloads
Date: Fri, 21 Apr 2017 11:34:45 -0700 [thread overview]
Message-ID: <20170421183445.GB12755@gmail.com> (raw)
In-Reply-To: <20091.1492783037@warthog.procyon.org.uk>
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
next prev parent reply other threads:[~2017-04-21 18:34 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-21 8:30 [PATCH 0/5] KEYS: " Eric Biggers
2017-04-21 8:30 ` [PATCH 1/5] KEYS: sanitize add_key() and keyctl() " Eric Biggers
2017-04-28 17:57 ` Eric Biggers
2017-04-21 8:30 ` [PATCH 2/5] KEYS: user_defined: sanitize " Eric Biggers
2017-04-21 8:30 ` [PATCH 3/5] KEYS: encrypted: sanitize all key material Eric Biggers
2017-04-21 8:30 ` [PATCH 4/5] KEYS: trusted: " Eric Biggers
2017-04-21 8:30 ` [PATCH 5/5] KEYS: sanitize key structs before freeing Eric Biggers
2017-04-21 13:57 ` [PATCH 2/5] KEYS: user_defined: sanitize key payloads David Howells
2017-04-21 18:34 ` Eric Biggers [this message]
2017-04-24 14:14 ` David Howells
2017-04-21 14:31 ` [PATCH 3/5] KEYS: encrypted: sanitize all key material David Howells
2017-04-21 18:24 ` Eric Biggers
2017-04-24 14:14 ` David Howells
2017-04-27 15:09 ` [PATCH 0/5] KEYS: sanitize key payloads David Howells
2017-04-27 17:43 ` Eric Biggers
2017-06-02 15:34 ` [PATCH 1/5] KEYS: sanitize add_key() and keyctl() " David Howells
2017-06-02 17:24 ` Eric Biggers
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