{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-72491", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-72491" ], "published": "2026-08-15T06:04:33Z", "summary": "net/9p: fix race condition on rdma->state in trans_rdma.c", "details": "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.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.178", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-72491" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/4cee2b8766045059d5e0b8114837b4a8efe827ac" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5424138848eb7d7d8a7196676e90a2cbf2142454" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/3970a19a80de530b801b6256354d4a529a9a2d6c" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/151f8cf5b23d8a534d884432a82a6d54d5a61989" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/13bf9879b778b2f4b260b45bed18f31806120d1e" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ebbcbe5c0db215feecc17def06178da443f4eea6" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/7d54894a1ee265a72d70f7cae1da6cc774cccc71" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-17T05:50:24Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 9.8, "cvss_v3_severity": "Critical", "scenario": "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\u2014automated 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." } } }