linux-kernel - Re: [bug report] nvme: NULL pointer dereference in nvmet_setup

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Message-ID: <20220823161255.GA21462@lst.de>
Date:   Tue, 23 Aug 2022 18:12:55 +0200
From:   Christoph Hellwig <hch@....de>
To:     Hannes Reinecke <hare@...e.de>
Cc:     Tal Lossos <tallossos@...il.com>, sagi@...mberg.me, kch@...dia.com,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [bug report] nvme: NULL pointer dereference in nvmet_setup_auth

On Tue, Aug 23, 2022 at 03:23:37PM +0300, Tal Lossos wrote:
> Hello,
> There is a NULL pointer dereference in nvmet_setup_auth() introduced
> in commit db1312dd95488b5e6ff362ff66fcf953a46b1821 causing a DoS.
> As of v6.0-rc2, in target/auth.c:196, if there is an error with
> ctrl->ctrl_key, it gets reassigned to NULL, and one line afterwards,
> it gets dereferenced in the call for pr_debug():

Hannes, can you look into this?

> 
> ctrl->ctrl_key = nvme_auth_extract_key(host->dhchap_ctrl_secret + 10,
>     host->dhchap_ctrl_key_hash);
> if (IS_ERR(ctrl->ctrl_key)) {
>     ret = PTR_ERR(ctrl->ctrl_key);
>     ctrl->ctrl_key = NULL;   <--- Assigning NULL
> }
> pr_debug("%s: using ctrl hash %s key %*ph\n", __func__,
> ctrl->ctrl_key->hash > 0 ?   <--- NULL pointer dereference
> nvme_auth_hmac_name(ctrl->ctrl_key->hash) : "none",
> (int)ctrl->ctrl_key->len, ctrl->ctrl_key->key);
> 
> This bug occurs probably due to a missing goto statement (goto out_unlock).
> 
> Best Regards,
> Tal Lossos
---end quoted text---