oss-security - CVE-2023-0122: Linux kernel: Pre-Auth Remote DoS in NVMe

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date: Thu, 12 Jan 2023 16:12:30 +0200
From: Tal Lossos <tallossos@...il.com>
To: oss-security@...ts.openwall.com
Subject: CVE-2023-0122: Linux kernel: Pre-Auth Remote DoS in NVMe

Hi all,

# Description
A NULL Pointer Dereference bug in nvmet_setup_auth
(drivers/nvme/target/auth.c) can be triggered remotely to cause a DoS.
Since the bug occurs in the authentication feature, it can be easily
triggered by an unauthorized client in the pre-auth stage.
Versions affected - v6.0-rc1 to v6.0-rc3 (fixed in v6.0-rc4).

# Vulnerability
The vulnerability is caused by a missing goto statement after
assigning ctrl->ctrl_key to NULL, thus causing a NULL Pointer
Dereference afterward:
---
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);
---

# Exploitation
If an invalid dhchap_ctrl_key (e.g., ‘DHHC-1:00:AAAA:’) is configured
in the NVMe target under a host object, when a remote client tries to
connect to the NVMe subsystem (e.g., NVMe-TCP), the NULL Pointer
Dereference would be triggered thus causing a DoS on the target
machine.
Running ‘nvme connect’ from a client to the remote subsystem would
cause a DoS on the remote target.
To bypass the authentication feature, we can pass the allowed client’s
NQN to the ‘nvme connect’ command, which can be obtained by network
sniffing.

# Patch
Bug report - https://lore.kernel.org/linux-nvme/20220823161255.GA21462@lst.de/T/#t
Fix patch - https://lore.kernel.org/linux-nvme/20220831045908.GC18042@lst.de/T/#u

Regards,
Tal Lossos

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.