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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | net/rds: use wq_has_sleeper() in rds_cong_map_updated() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:05:58.866Z
Reserved: 2026-09-11T19:38:34.785Z
Link: CVE-2026-90081
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:16:57.423
Modified: 2026-09-17T17:16:57.423
Link: CVE-2026-90081
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.