Re: [PATCH BUGFIX -v2 -rc4] Smack: Respect 'unlabeled' netlabelmode

[Andrew Morton]

On Sat, 31 May 2008 02:57:51 +0300
"Ahmed S. Darwish" <darwish.07@xxxxxxxxx> wrote:

> +		mutex_lock(&smack_ambient_lock);
> +		nlsp->domain = kstrdup(smack_net_ambient, GFP_ATOMIC);
> +		mutex_unlock(&smack_ambient_lock);

no no no no no.  And no.

GFP_ATOMIC is *unreliable*.  Using it in a "security" feature is a bug
- if it fails, the feature isn't secure any more.

Failing to check the kmalloc() return value might be a bug.

If we _need_ GFP_ATOMIC here then taking a mutex in a cannot-sleep
context is a bug.

The patch adds a kmalloc but doesn't add a kfree.  Is it leaky?

Finally, why is there a need to take a lock around a single store
instruction?
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