CVE-2021-47041

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

nvmet-tcp: fix incorrect locking in state_change sk callback

We are not changing anything in the TCP connection state so

we should not take a write_lock but rather a read lock.

This caused a deadlock when running nvmet-tcp and nvme-tcp

on the same system, where state_change callbacks on the

host and on the controller side have causal relationship

and made lockdep report on this with blktests:

================================

WARNING: inconsistent lock state

5.12.0-rc3 #1 Tainted: G I

--------------------------------

inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-R} usage.

nvme/1324 [HC0[0]:SC0[0]:HE1:SE1] takes:

ffff888363151000 (clock-AF_INET){++-?}-{2:2}, at: nvme_tcp_state_change+0x21/0x150 [nvme_tcp]

{IN-SOFTIRQ-W} state was registered at:

__lock_acquire+0x79b/0x18d0

lock_acquire+0x1ca/0x480

_raw_write_lock_bh+0x39/0x80

nvmet_tcp_state_change+0x21/0x170 [nvmet_tcp]

tcp_fin+0x2a8/0x780

tcp_data_

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References