CVE-2021-47382: s390/qeth: fix deadlock during failing recovery

Vulnerability summary

CVE-2021-47382 is a medium (CVSS 4.7) vulnerability in linux. EPSS estimates a 0.15% chance of exploitation in the next 30 days, higher than 4.4% of scored vulnerabilities.

Timeline

1. 21-05-2024
   PublishedVulnerability first disclosed.
2. 23-05-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: s390/qeth: fix deadlock during failing recovery Commit 0b9902c1fcc5 ("s390/qeth: fix deadlock during recovery") removed taking discipline_mutex inside qeth_do_reset(), fixing potential deadlocks. An error path was missed though, that still takes discipline_mutex and thus has the original deadlock potential. Intermittent deadlocks were seen when a qeth channel path is configured offline, causing a race between qeth_do_reset and ccwgroup_remove. Call qeth_set_offline() directly in the qeth_do_reset() error case and then a new variant of ccwgroup_set_offline(), without taking discipline_mutex.

• CWE-362Concurrent Execution using Shared Resource with Improper SynchronizationThe product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
• CWE-667Improper LockingThe product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.