CVE-2024-26627: scsi: core: Move scsi_host_busy() out of host lock for waking up EH handler

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-03-06 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: core: Move scsi_host_busy() out of host lock for waking up EH handler Inside scsi_eh_wakeup(), scsi_host_busy() is called & checked with host lock every time for deciding if error handler kthread needs to be waken up. This can be too heavy in case of recovery, such as: - N hardware queues - queue depth is M for each hardware queue - each scsi_host_busy() iterates over (N * M) tag/requests If recovery is triggered in case that all requests are in-flight, each scsi_eh_wakeup() is strictly serialized, when scsi_eh_wakeup() is called for the last in-flight request, scsi_host_busy() has been run for (N * M - 1) times, and request has been iterated for (N*M - 1) * (N * M) times. If both N and M are big enough, hard lockup can be triggered on acquiring host lock, and it is observed on mpi3mr(128 hw queues, queue depth 8169). Fix the issue by calling scsi_host_busy() outside the host lock. We don't need the host lock for getting busy count because host the lock never covers that. [mkp: Drop unnecessary 'busy' variables pointed out by Bart]

Affected products

Linux kernel: from 5.5 before 5.10.210; from 5.11 before 5.15.149; from 5.16 before 6.1.77; from 6.2 before 6.6.16; from 6.7 before 6.7.4; 6.8-rc1, 6.8-rc2 — fixed in 5.10.210, 5.15.149, 6.1.77, 6.6.16, 6.7.4

How to fix

Upgrade to a fixed version: Linux kernel 5.10.210, 5.15.149, 6.1.77, 6.6.16. Check the vendor advisory for mitigations.

References

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