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From: Al Viro <>
To: Casey Schaufler <>
Subject: Re: [PATCH] Version 8 (2.6.23) Smack: Simplified Mandatory Access Control Kernel
Date: Thu, 18 Oct 2007 05:57:05 +0100
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, Oct 16, 2007 at 09:17:40PM -0700, Casey Schaufler wrote:

At random:

> +static int smack_netlabel(struct sock *sk)
> +{
> +	static int initialized;
> +	struct socket_smack *ssp = sk->sk_security;
> +	struct netlbl_lsm_secattr secattr;
> +	int rc = 0;
> +
> +	if (!initialized) {
> +		smk_cipso_doi();
> +		initialized = 1;
> +	}

And just what happens if another task calls the same while we are
blocked on allocation in smk_cipso_doi()?

Another problem is your handling of smk_known - you add to head under
mutex; fine.  However, you read without one _and_ have no barriers
in initializing new list entries.

Think what happens if CPU1 adds to list and CPU2 sees write to smk_known
*before* it sees write to ->smk_next.  We see a single-element list and
we'll be lucky if that single entry won't be FUBAR.

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-17  4:17 Casey Schaufler
2007-10-18  4:57 ` Al Viro [this message]
2007-10-18  5:10   ` Al Viro
2007-10-19 12:39     ` Ahmed S. Darwish
2007-10-18 20:13   ` Casey Schaufler
2007-10-18 20:26     ` Al Viro
2007-10-21  1:40 ` [PATCH] Smackv8: Omit non-cipso labels in cipso_seq_start Ahmed S. Darwish
2007-10-21  2:25   ` [PATCH] Smackv8: Safe lockless {cipso,load} read operation Ahmed S. Darwish

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