CVE-2026-98072
Received Received - Intake

Race Condition in Linux Kernel RDS Module Leads to Deadlock

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/rds: use wq_has_sleeper() in release_in_xmit() release_in_xmit() clears RDS_IN_XMIT with clear_bit_unlock() and then checks waitqueue_active() to decide whether anyone needs waking. clear_bit_unlock() is only a release operation: it orders the critical section before the bit clear, but does not order the subsequent plain load of the wait queue head after it. The waiter side does the mirror image - it adds itself to the wait queue and then tests the bit. That is the classic store-buffering pattern: the releasing CPU can read the wait queue as empty while the waiting CPU still reads the bit as set, so the sleeper is never woken. The waiters are rds_conn_shutdown() and rds_tcp_reset_callbacks(), both in uninterruptible wait_event() with no timeout. A lost wake-up strands the shutdown worker on its single-threaded workqueue until some other sender releases the bit again - and on a connection that is being torn down precisely because it failed, there may never be another sender. The barrier used to be there: release_in_xmit() did clear_bit() followed by smp_mb__after_atomic() until commit 1422f28826d2 ("rds: introduce acquire/release ordering in acquire/release_in_xmit()") folded both into clear_bit_unlock(), which strengthened the lock hand-off but silently dropped the full barrier the wake-up check depends on. The refill counterpart, release_refill() in net/rds/ib_recv.c, still carries its smp_mb__after_atomic() for exactly this reason. Use wq_has_sleeper(), which is waitqueue_active() preceded by the required full barrier.

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
CVE-2026-98072
EUVD
EUVD-2026-86725

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where a missing memory barrier in the RDS (Reliable Datagram Sockets) subsystem causes a lost wake-up condition. The issue occurs in release_in_xmit() when clearing a bit and checking a wait queue without proper synchronization. This can strand shutdown processes indefinitely.

Detection Guidance

This vulnerability is specific to the Linux kernel's RDS (Reliable Datagram Sockets) implementation and may not have direct detection commands. Monitoring for hung processes in the rds_conn_shutdown() or rds_tcp_reset_callbacks() functions, particularly during connection teardown, could indicate the issue. Check kernel logs for stalled workqueue threads or connection shutdown delays.

Impact Analysis

If you use systems running vulnerable Linux kernels, network connections may fail to properly shut down. This could lead to hung processes, resource leaks, or system instability during network operations, particularly in high-reliability environments.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. If patching is not immediately possible, consider disabling the RDS protocol if it is not required, or restrict its use to trusted networks. Monitor system logs for hung processes or connection shutdown failures as potential indicators of exploitation.

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