{"id":"CVE-2026-72491","state":"PUBLISHED","title":"net/9p: fix race condition on rdma->state in trans_rdma.c","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/9p: fix race condition on rdma->state in trans_rdma.c\n\nThe rdma->state field is modified without holding req_lock in both\nrecv_done() and p9_cm_event_handler(), while rdma_request() accesses\nthe same field under the req_lock spinlock. This inconsistent locking\ncreates a race condition:\n\n- recv_done() running in softirq completion context sets\n  rdma->state = P9_RDMA_FLUSHING without acquiring req_lock\n\n- p9_cm_event_handler() modifies rdma->state at multiple points\n  (ADDR_RESOLVED, ROUTE_RESOLVED, ESTABLISHED, CLOSED) without\n  req_lock\n\n- rdma_request() uses spin_lock_irqsave(&rdma->req_lock, flags) to\n  protect the read-modify-write of rdma->state\n\nThe race can cause lost state transitions: recv_done() or the CM\nevent handler could set state to FLUSHING/CLOSED while rdma_request()\nis concurrently checking or modifying state under the lock, leading to\nthe FLUSHING transition being silently overwritten by CLOSING. This\ncorrupts the connection state machine and can cause use-after-free on\nRDMA request objects during teardown.\n\nFix by adding req_lock protection to all rdma->state modifications in\nrecv_done() and p9_cm_event_handler(), matching the pattern already\nused in rdma_request(). Use spin_lock_irqsave/spin_unlock_irqrestore\nin the CM event handler since it can race with recv_done() which runs\nin softirq context.\n\nTested with a kernel module that races two threads (simulating\nrdma_request and recv_done/CM handler) on rdma->state with proper\nlocking: 5.5M+ FLUSHING writes over 27M iterations with 0 lost\ntransitions.","publishedAt":"2026-08-15T05:57:26.281Z","updatedAt":"2026-10-16T18:55:26.515Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"4cee2b8766045059d5e0b8114837b4a8efe827ac","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"5424138848eb7d7d8a7196676e90a2cbf2142454","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"3970a19a80de530b801b6256354d4a529a9a2d6c","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"151f8cf5b23d8a534d884432a82a6d54d5a61989","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"13bf9879b778b2f4b260b45bed18f31806120d1e","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"ebbcbe5c0db215feecc17def06178da443f4eea6","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"7d54894a1ee265a72d70f7cae1da6cc774cccc71","versionType":"git"},{"version":"3479b3c35e82ed10aa0ca2ee9e78c4eded06ba62","status":"affected","versionType":"git"},{"version":"c01ddaa54d7411e964ffd250c018d8469c5852f2","status":"affected","versionType":"git"},{"version":"9e69c673fe077b8dc491cd8406c9bdcb1f76dee2","status":"affected","versionType":"git"},{"version":"e48e7e27e4dfd00c81e0381e7cee610cce021452","status":"affected","versionType":"git"},{"version":"4.4.185","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"4.9.185","status":"affected","lessThan":"4.10","versionType":"semver"},{"version":"4.14.132","status":"affected","lessThan":"4.15","versionType":"semver"},{"version":"4.19.57","status":"affected","lessThan":"4.20","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_rdma.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.20","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.20","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_rdma.c"]}],"references":["https://git.kernel.org/stable/c/4cee2b8766045059d5e0b8114837b4a8efe827ac","https://git.kernel.org/stable/c/5424138848eb7d7d8a7196676e90a2cbf2142454","https://git.kernel.org/stable/c/3970a19a80de530b801b6256354d4a529a9a2d6c","https://git.kernel.org/stable/c/8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b","https://git.kernel.org/stable/c/151f8cf5b23d8a534d884432a82a6d54d5a61989","https://git.kernel.org/stable/c/13bf9879b778b2f4b260b45bed18f31806120d1e","https://git.kernel.org/stable/c/ebbcbe5c0db215feecc17def06178da443f4eea6","https://git.kernel.org/stable/c/7d54894a1ee265a72d70f7cae1da6cc774cccc71"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72491.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72491","state":"PUBLISHED","datePublished":"2026-08-15T05:57:26.281Z","dateUpdated":"2026-10-16T18:55:26.515Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.936Z"},"containers":{"cna":{"title":"net/9p: fix race condition on rdma->state in trans_rdma.c","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/9p: fix race condition on rdma->state in trans_rdma.c\n\nThe rdma->state field is modified without holding req_lock in both\nrecv_done() and p9_cm_event_handler(), while rdma_request() accesses\nthe same field under the req_lock spinlock. This inconsistent locking\ncreates a race condition:\n\n- recv_done() running in softirq completion context sets\n  rdma->state = P9_RDMA_FLUSHING without acquiring req_lock\n\n- p9_cm_event_handler() modifies rdma->state at multiple points\n  (ADDR_RESOLVED, ROUTE_RESOLVED, ESTABLISHED, CLOSED) without\n  req_lock\n\n- rdma_request() uses spin_lock_irqsave(&rdma->req_lock, flags) to\n  protect the read-modify-write of rdma->state\n\nThe race can cause lost state transitions: recv_done() or the CM\nevent handler could set state to FLUSHING/CLOSED while rdma_request()\nis concurrently checking or modifying state under the lock, leading to\nthe FLUSHING transition being silently overwritten by CLOSING. This\ncorrupts the connection state machine and can cause use-after-free on\nRDMA request objects during teardown.\n\nFix by adding req_lock protection to all rdma->state modifications in\nrecv_done() and p9_cm_event_handler(), matching the pattern already\nused in rdma_request(). Use spin_lock_irqsave/spin_unlock_irqrestore\nin the CM event handler since it can race with recv_done() which runs\nin softirq context.\n\nTested with a kernel module that races two threads (simulating\nrdma_request and recv_done/CM handler) on rdma->state with proper\nlocking: 5.5M+ FLUSHING writes over 27M iterations with 0 lost\ntransitions."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"4cee2b8766045059d5e0b8114837b4a8efe827ac","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"5424138848eb7d7d8a7196676e90a2cbf2142454","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"3970a19a80de530b801b6256354d4a529a9a2d6c","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"151f8cf5b23d8a534d884432a82a6d54d5a61989","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"13bf9879b778b2f4b260b45bed18f31806120d1e","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"ebbcbe5c0db215feecc17def06178da443f4eea6","versionType":"git"},{"version":"473c7dd1d7b59ff8f88a5154737e3eac78a96e5b","status":"affected","lessThan":"7d54894a1ee265a72d70f7cae1da6cc774cccc71","versionType":"git"},{"version":"3479b3c35e82ed10aa0ca2ee9e78c4eded06ba62","status":"affected","versionType":"git"},{"version":"c01ddaa54d7411e964ffd250c018d8469c5852f2","status":"affected","versionType":"git"},{"version":"9e69c673fe077b8dc491cd8406c9bdcb1f76dee2","status":"affected","versionType":"git"},{"version":"e48e7e27e4dfd00c81e0381e7cee610cce021452","status":"affected","versionType":"git"},{"version":"4.4.185","status":"affected","lessThan":"4.5","versionType":"semver"},{"version":"4.9.185","status":"affected","lessThan":"4.10","versionType":"semver"},{"version":"4.14.132","status":"affected","lessThan":"4.15","versionType":"semver"},{"version":"4.19.57","status":"affected","lessThan":"4.20","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_rdma.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.20","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.20","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_rdma.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4cee2b8766045059d5e0b8114837b4a8efe827ac"},{"url":"https://git.kernel.org/stable/c/5424138848eb7d7d8a7196676e90a2cbf2142454"},{"url":"https://git.kernel.org/stable/c/3970a19a80de530b801b6256354d4a529a9a2d6c"},{"url":"https://git.kernel.org/stable/c/8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b"},{"url":"https://git.kernel.org/stable/c/151f8cf5b23d8a534d884432a82a6d54d5a61989"},{"url":"https://git.kernel.org/stable/c/13bf9879b778b2f4b260b45bed18f31806120d1e"},{"url":"https://git.kernel.org/stable/c/ebbcbe5c0db215feecc17def06178da443f4eea6"},{"url":"https://git.kernel.org/stable/c/7d54894a1ee265a72d70f7cae1da6cc774cccc71"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The 9p RDMA client processes RDMA receive completions and CM disconnect events from the remote peer in recv_done() and p9_cm_event_handler(); a malicious or compromised 9p server over RoCE/iWARP can trigger err_out and concurrent teardown without local access.\nAC:L - The attacker controls both sides of the race by sending malformed 9p RDMA replies to drive recv_done() into err_out while forcing disconnects and concurrent rdma_request() error paths; no uncontrollable memory layout or rare victim state is required.\nPR:N - A remote malicious 9p RDMA server needs no credentials on the victim kernel; HPC clusters and virtio-9p backends with persistent trans=rdma mounts let the server alone time malformed replies against in-flight client requests.\nUI:N - No per-attack victim action is needed on existing 9p RDMA mounts—automated workloads, parallel I/O, and server-initiated RDMA disconnects concurrently reach recv_done() and rdma_request() during normal filesystem operation.\nS:U - Impact is kernel heap corruption and local privilege escalation within the victim kernel security domain; UAF on p9_req_t during RDMA teardown does not cross VM, container, or IOMMU isolation boundaries.\nC:H - Lost FLUSHING state transitions corrupt the connection teardown state machine and cause use-after-free on RDMA request (p9_req_t) objects; UAF provides attacker-influenced freed-heap contents usable for arbitrary kernel memory disclosure.\nI:H - Corrupted rdma->state frees in-flight p9_req_t structures while send_done() and p9_client_cb() still hold references, enabling heap grooming and arbitrary kernel write or control-flow hijack primitives.\nA:H - Use-after-free during RDMA request teardown causes kernel oops or panic when dangling p9_req_t objects are accessed, and state-machine corruption alone can hang or crash the 9p RDMA transport."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:44:52.224Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.185"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.185"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.132"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.57"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72491","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:50:50.731501Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:55:26.515Z"}}]}}}