CVE-2026-72491
Received
Received - Intake
Race Condition in Linux Kernel 9P RDMA Transport
Vulnerability report for CVE-2026-72491, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-15
Last updated on: 2026-08-15
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
net/9p: fix race condition on rdma->state in trans_rdma.c
The rdma->state field is modified without holding req_lock in both
recv_done() and p9_cm_event_handler(), while rdma_request() accesses
the same field under the req_lock spinlock. This inconsistent locking
creates a race condition:
- recv_done() running in softirq completion context sets
rdma->state = P9_RDMA_FLUSHING without acquiring req_lock
- p9_cm_event_handler() modifies rdma->state at multiple points
(ADDR_RESOLVED, ROUTE_RESOLVED, ESTABLISHED, CLOSED) without
req_lock
- rdma_request() uses spin_lock_irqsave(&rdma->req_lock, flags) to
protect the read-modify-write of rdma->state
The race can cause lost state transitions: recv_done() or the CM
event handler could set state to FLUSHING/CLOSED while rdma_request()
is concurrently checking or modifying state under the lock, leading to
the FLUSHING transition being silently overwritten by CLOSING. This
corrupts the connection state machine and can cause use-after-free on
RDMA request objects during teardown.
Fix by adding req_lock protection to all rdma->state modifications in
recv_done() and p9_cm_event_handler(), matching the pattern already
used in rdma_request(). Use spin_lock_irqsave/spin_unlock_irqrestore
in the CM event handler since it can race with recv_done() which runs
in softirq context.
Tested with a kernel module that races two threads (simulating
rdma_request and recv_done/CM handler) on rdma->state with proper
locking: 5.5M+ FLUSHING writes over 27M iterations with 0 lost
transitions.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
