CVE-2026-72491net/9p: fix race condition on rdma->state in trans_rdma.c

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.72% · top 45% of all CVEs (13 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.

Affected products

• Linux · Linux

  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 4cee2b8766045059d5e0b8114837b4a8efe827ac
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 5424138848eb7d7d8a7196676e90a2cbf2142454
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 3970a19a80de530b801b6256354d4a529a9a2d6c
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 151f8cf5b23d8a534d884432a82a6d54d5a61989
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 13bf9879b778b2f4b260b45bed18f31806120d1e
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < ebbcbe5c0db215feecc17def06178da443f4eea6
  • affected 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b – < 7d54894a1ee265a72d70f7cae1da6cc774cccc71
  • affected 3479b3c35e82ed10aa0ca2ee9e78c4eded06ba62
  • affected c01ddaa54d7411e964ffd250c018d8469c5852f2
  • affected 9e69c673fe077b8dc491cd8406c9bdcb1f76dee2
  • affected e48e7e27e4dfd00c81e0381e7cee610cce021452
  • affected 4.4.185 – < 4.5
  • affected 4.9.185 – < 4.10
  • affected 4.14.132 – < 4.15
  • affected 4.19.57 – < 4.20

• Linux · Linux

  • affected 4.20
  • unaffected < 4.20
  • unaffected 5.10.261 – ≤ 5.10.*
  • unaffected 5.15.212 – ≤ 5.15.*
  • unaffected 6.1.178 – ≤ 6.1.*
  • unaffected 6.6.145 – ≤ 6.6.*
  • unaffected 6.12.97 – ≤ 6.12.*
  • unaffected 6.18.40 – ≤ 6.18.*
  • unaffected 7.1.5 – ≤ 7.1.*
  • unaffected 7.2 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-59390 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-72491](https://cveledger.app/badge/CVE-2026-72491.svg)](https://cveledger.app/cve/CVE-2026-72491)

Record last updated 16 Oct 2026, 18:55 UTC.