{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-74692", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-74692" ], "published": "2026-08-22T15:32:12Z", "summary": "net/smc: fix TOCTOU race between smc_listen_out() and listener close", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix TOCTOU race between smc_listen_out() and listener close\n\nsmc_listen_out() reads lsmc->sk.sk_state without the listener lock,\nthen acquires lock_sock_nested() only after the check passes. This\nopens a window where smc_close_active() can transition the listener\nto SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept\nqueue, and release the lock, all between the lockless read and the\ndelayed lock acquisition:\n\n smc_listen_work (smc_hs_wq) smc_close_active()\n ------------------------------- -------------------------\n release_sock(child)\n if (sk_state == SMC_LISTEN) TRUE\n lock_sock(listener)\n sk_state = SMC_CLOSED\n smc_close_cleanup_listen()\n release_sock(listener)\n flush_work(tcp_listen_work)\n lock_sock_nested(listener)\n smc_accept_enqueue(listener, child) /* child enqueued on dead listener */\n\nsmc_close_active() flushes only tcp_listen_work. Work items already\ndispatched onto smc_hs_wq for the CLC handshake continue running\nunguarded. smc_accept_enqueue() takes a sock_hold() on the child that\nis never released, so the child smc_sock, its clcsock, and the\nreference all leak. A remote peer that opens TCP connections while the\nserver calls close() can exhaust kernel memory.\n\nMove lock_sock_nested() to before the sk_state check so that the test\nand the enqueue are atomic under the listener lock.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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": "6.1.183", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-74692" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/53c7938d8bcfde3296ec1a347ba2a9393c1fdcfa" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/feb71634bb1abab3e8fb5cde874b27001cc1282e" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/01865e1ddb126b25ac9eba5cdd7ec49e11183a64" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/00f89433777236ced4771211047fb5d4cd581cea" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/78e5ebcd1c10ed7c8bda0a99e0abd5b62da86d67" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ff5bcd804b5bc5c64736b7d318c20e12ea9506b8" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/185a4caeecabc150106deda1da170b09f2ad803f" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-25T05:42:41Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.5, "cvss_v3_severity": "High", "scenario": "AV:N - The bug fires when smc_listen_work() on smc_hs_wq finishes an inbound SMC/TCP handshake queued by smc_tcp_listen_work() for each remote connection to an AF_SMC listener, so any network peer that reaches the listener port drives the full path via SYN and CLC messages.\nAC:L - The attacker controls handshake completions by flooding SMC-capable TCP connections and overlapping them with listener close(), either by timing floods against restarts or locally by running server and client together; smc_close_active() only flushes tcp_listen_work, leaving smc_hs_wq workers racing through the unlocked sk_state check.\nPR:N - SMC performs no authentication; smc_create() and smc_listen() enforce no capabilities, and smc_listen_work() processes the CLC handshake immediately after TCP accept before any credential verification, so an unauthenticated remote peer need only reach the listener port.\nUI:N - Exploitation requires only inbound network connections and kernel handshake/close processing; no end-user action such as opening a file or mounting a filesystem is needed, and listener shutdown during deployments or restarts is routine automated server behavior.\nS:U - The leak accumulates orphaned smc_sock structures and clcsock references within the kernel networking subsystem on the targeted host; it does not cross VM, container, IOMMU, or other security boundaries.\nC:N - The bug is an unreleased sock_hold() leaving child sockets on a closed listener accept queue; objects are never freed prematurely, so there is no out-of-bounds read, use-after-free dereference, or kernel data disclosure to the attacker.\nI:N - Only reference counts are incremented without matching decrements; no memory is written out of bounds, no freed object is reused, and no control-flow or integrity primitive is obtained\u2014only unreclaimable kernel allocations accumulate.\nA:H - Each successful race permanently leaks a child smc_sock, its clcsock, and sock references that smc_close_cleanup_listen() can never drain; a remote peer repeating handshakes during listener close can exhaust kernel memory and cause system-wide denial of service." } } }