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GET /api/patches/2224793/?format=api
{ "id": 2224793, "url": "http://patchwork.ozlabs.org/api/patches/2224793/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260418172844.1333378-2-charsyam@gmail.com/", "project": { "id": 12, "url": "http://patchwork.ozlabs.org/api/projects/12/?format=api", "name": "Linux CIFS Client", "link_name": "linux-cifs-client", "list_id": "linux-cifs.vger.kernel.org", "list_email": "linux-cifs@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260418172844.1333378-2-charsyam@gmail.com>", "list_archive_url": null, "date": "2026-04-18T17:28:43", "name": "[1/2] ksmbd: fix active_num_conn leak when alloc_transport() fails", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "d65d0c56d3e0cfd2a4daf4f8ee18f47615108b35", "submitter": { "id": 93166, "url": "http://patchwork.ozlabs.org/api/people/93166/?format=api", "name": "DaeMyung Kang", "email": "charsyam@gmail.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260418172844.1333378-2-charsyam@gmail.com/mbox/", "series": [ { "id": 500457, "url": "http://patchwork.ozlabs.org/api/series/500457/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=500457", "date": "2026-04-18T17:28:42", "name": "ksmbd: connection accounting and session teardown fixes", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/500457/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2224793/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2224793/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linux-cifs+bounces-10900-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-cifs@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=S4a7aoy3;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c15:e001:75::12fc:5321; helo=sin.lore.kernel.org;\n envelope-from=linux-cifs+bounces-10900-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)", "smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com\n header.b=\"S4a7aoy3\"", "smtp.subspace.kernel.org;\n arc=none smtp.client-ip=209.85.214.176", "smtp.subspace.kernel.org;\n dmarc=pass (p=none dis=none) header.from=gmail.com", "smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=gmail.com" ], "Received": [ "from sin.lore.kernel.org (sin.lore.kernel.org\n [IPv6:2600:3c15:e001:75::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fyf0g3tWlz1yGt\n\tfor <incoming@patchwork.ozlabs.org>; Sun, 19 Apr 2026 03:30:43 +1000 (AEST)", "from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sin.lore.kernel.org (Postfix) with ESMTP id 5223B300515F\n\tfor <incoming@patchwork.ozlabs.org>; Sat, 18 Apr 2026 17:30:40 +0000 (UTC)", "from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 0B06932C8B;\n\tSat, 18 Apr 2026 17:30:38 +0000 (UTC)", "from mail-pl1-f176.google.com (mail-pl1-f176.google.com\n [209.85.214.176])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id CC66A18C2C\n\tfor <linux-cifs@vger.kernel.org>; Sat, 18 Apr 2026 17:30:36 +0000 (UTC)", "by mail-pl1-f176.google.com with SMTP id\n d9443c01a7336-2ab08e6c553so2429575ad.3\n for <linux-cifs@vger.kernel.org>;\n Sat, 18 Apr 2026 10:30:36 -0700 (PDT)", "from ser8.. 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The decrement normally\nhappens in ksmbd_tcp_disconnect() at the end of the connection's\nlifetime.\n\nIf alloc_transport() fails in ksmbd_tcp_new_connection(), the function\nreleases the socket and returns -ENOMEM without going through\nksmbd_tcp_disconnect(), so active_num_conn never gets decremented.\nUnder memory pressure, repeated failures monotonically inflate the\ncounter until max_connections is reached and new clients are refused\nindefinitely.\n\nDecrement active_num_conn on this error path, matching the accounting\nrule used by ksmbd_kthread_fn() and ksmbd_tcp_disconnect().\n\nCommit 77ffbcac4e56 (\"smb: server: fix leak of active_num_conn in\nksmbd_tcp_new_connection()\") fixed the sibling leak on the kthread_run()\nfailure path; this patch closes the remaining one.\n\nReproduced with a debug build that adds a temporary module parameter\nguarding an early return at the top of alloc_transport(), forcing\nthe first N accept-time transport allocations to fail:\n\n * Configure ksmbd with \"max connections = 3\".\n * Force 5 successive alloc_transport() failures at the accept path.\n * Without the fix: active_num_conn drifts up to max_connections and\n subsequent legitimate mount.cifs attempts are refused with\n \"ksmbd: Limit the maximum number of connections(3)\" in dmesg.\n * With the fix: the counter is correctly decremented on each\n failure and legitimate mounts continue to succeed.\n\nTested by injecting 5 alloc_transport() failures with\nmax_connections=3 and verifying that subsequent mount.cifs attempts\nstill succeed on the patched kernel while the unpatched kernel\nrefuses them.\n\nFixes: 0d0d4680db22 (\"ksmbd: add max connections parameter\")\nCc: stable@vger.kernel.org\nSigned-off-by: DaeMyung Kang <charsyam@gmail.com>\n---\n fs/smb/server/transport_tcp.c | 2 ++\n 1 file changed, 2 insertions(+)", "diff": "diff --git a/fs/smb/server/transport_tcp.c b/fs/smb/server/transport_tcp.c\nindex 7e29b06820e2..400412444838 100644\n--- a/fs/smb/server/transport_tcp.c\n+++ b/fs/smb/server/transport_tcp.c\n@@ -182,6 +182,8 @@ static int ksmbd_tcp_new_connection(struct socket *client_sk)\n \n \tt = alloc_transport(client_sk);\n \tif (!t) {\n+\t\tif (server_conf.max_connections)\n+\t\t\tatomic_dec(&active_num_conn);\n \t\tsock_release(client_sk);\n \t\treturn -ENOMEM;\n \t}\n", "prefixes": [ "1/2" ] }