From: Kees Cook <keescook@chromium.org>
To: Ondrej Mosnacek <omosnace@redhat.com>
Cc: selinux@vger.kernel.org, Paul Moore <paul@paul-moore.com>,
NitinGote <nitin.r.gote@intel.com>,
kernel-hardening@lists.openwall.com,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH] selinux: check sidtab limit before adding a new entry
Date: Mon, 22 Jul 2019 09:50:26 -0700 [thread overview]
Message-ID: <201907220949.AFB5B68@keescook> (raw)
In-Reply-To: <20190722132111.25743-1-omosnace@redhat.com>
On Mon, Jul 22, 2019 at 03:21:11PM +0200, Ondrej Mosnacek wrote:
> We need to error out when trying to add an entry above SIDTAB_MAX in
> sidtab_reverse_lookup() to avoid overflow on the odd chance that this
> happens.
>
> Fixes: ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve performance")
> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Is this reachable from unprivileged userspace?
> ---
> security/selinux/ss/sidtab.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
> index e63a90ff2728..54c1ba1e79ab 100644
> --- a/security/selinux/ss/sidtab.c
> +++ b/security/selinux/ss/sidtab.c
> @@ -286,6 +286,11 @@ static int sidtab_reverse_lookup(struct sidtab *s, struct context *context,
> ++count;
> }
>
> + /* bail out if we already reached max entries */
> + rc = -ENOMEM;
> + if (count == SIDTAB_MAX)
Do you want to use >= here instead?
-Kees
> + goto out_unlock;
> +
> /* insert context into new entry */
> rc = -ENOMEM;
> dst = sidtab_do_lookup(s, count, 1);
> --
> 2.21.0
>
--
Kees Cook
next prev parent reply other threads:[~2019-07-22 16:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 13:21 [PATCH] selinux: check sidtab limit before adding a new entry Ondrej Mosnacek
2019-07-22 14:17 ` William Roberts
2019-07-23 6:48 ` Ondrej Mosnacek
2019-07-22 16:50 ` Kees Cook [this message]
2019-07-23 0:36 ` Paul Moore
2019-07-23 6:48 ` Ondrej Mosnacek
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