From: Paul Moore <paul@paul-moore.com>
To: Ondrej Mosnacek <omosnace@redhat.com>,
NitinGote <nitin.r.gote@intel.com>
Cc: Kees Cook <keescook@chromium.org>,
kernel-hardening@lists.openwall.com,
Stephen Smalley <sds@tycho.nsa.gov>,
Eric Paris <eparis@parisplace.org>,
SElinux list <selinux@vger.kernel.org>,
Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] selinux: convert struct sidtab count to refcount_t
Date: Mon, 22 Jul 2019 20:25:18 -0400 [thread overview]
Message-ID: <CAHC9VhSQLkRSby3-9PGZZrLMGB4Fe8ZZjupHRm0nVxco85A1fQ@mail.gmail.com> (raw)
In-Reply-To: <CAFqZXNs5vdQwoy2k=_XLiGRdyZCL=n8as6aL01Dw-U62amFREA@mail.gmail.com>
On Mon, Jul 22, 2019 at 9:18 AM Ondrej Mosnacek <omosnace@redhat.com> wrote:
> On Mon, Jul 22, 2019 at 1:35 PM NitinGote <nitin.r.gote@intel.com> wrote:
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
> >
> > Signed-off-by: NitinGote <nitin.r.gote@intel.com>
>
> Nack.
>
> The 'count' variable is not used as a reference counter here. It
> tracks the number of entries in sidtab, which is a very specific
> lookup table that can only grow (the count never decreases). I only
> made it atomic because the variable is read outside of the sidtab's
> spin lock and thus the reads and writes to it need to be guaranteed to
> be atomic. The counter is only updated under the spin lock, so
> insertions do not race with each other.
Agreed, this should be changed to use refcount_t.
--
paul moore
www.paul-moore.com
next prev parent reply other threads:[~2019-07-23 6:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 11:31 [PATCH] selinux: convert struct sidtab count to refcount_t NitinGote
2019-07-22 13:17 ` Ondrej Mosnacek
2019-07-23 0:25 ` Paul Moore [this message]
2019-07-23 5:44 ` Gote, Nitin R
2019-07-23 14:53 ` Jann Horn
2019-07-23 22:17 ` Kees Cook
2019-07-24 14:28 ` Jann Horn
2019-07-24 15:54 ` Kees Cook
2019-07-24 16:55 ` Jann Horn
2019-07-29 16:51 ` Kees Cook
2019-07-24 16:17 ` Ondrej Mosnacek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAHC9VhSQLkRSby3-9PGZZrLMGB4Fe8ZZjupHRm0nVxco85A1fQ@mail.gmail.com \
--to=paul@paul-moore.com \
--cc=eparis@parisplace.org \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nitin.r.gote@intel.com \
--cc=omosnace@redhat.com \
--cc=sds@tycho.nsa.gov \
--cc=selinux@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).