CVE-2024-26627 Information

Mar 07, 2024 cve

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 (NM - 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]

Reference

https://git.kernel.org/stable/c/f5944853f7a961fedc1227dc8f60393f8936d37c https://git.kernel.org/stable/c/d37c1c81419fdef66ebd0747cf76fb8b7d979059 https://git.kernel.org/stable/c/db6338f45971b4285ea368432a84033690eaf53c https://git.kernel.org/stable/c/65ead8468c21c2676d4d06f50b46beffdea69df1 https://git.kernel.org/stable/c/07e3ca0f17f579491b5f54e9ed05173d6c1d6fcb https://git.kernel.org/stable/c/4373534a9850627a2695317944898eb1283a2db0

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