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CVE-2026-72491

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 4.5, 4.10, 4.15, 4.20, 5.10.261, and 6 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: total

Summary

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

  1. CVE published
  2. CISA SSVC assessment

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

  3. Record last updated

Affected versions

  • Linux Linux

    From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 4cee2b8766045059d5e0b8114837b4a8efe827ac; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 5424138848eb7d7d8a7196676e90a2cbf2142454; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 3970a19a80de530b801b6256354d4a529a9a2d6c; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 151f8cf5b23d8a534d884432a82a6d54d5a61989; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 13bf9879b778b2f4b260b45bed18f31806120d1e; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in ebbcbe5c0db215feecc17def06178da443f4eea6; From 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b · fixed in 7d54894a1ee265a72d70f7cae1da6cc774cccc71; From 4.4.185 · fixed in 4.5; From 4.9.185 · fixed in 4.10; From 4.14.132 · fixed in 4.15; From 4.19.57 · fixed in 4.20

  • Linux Linux

    4.20

  • KernelLinux

    From 4.20.0 · fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5

References 8

git.kernel.org