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{ "id": 2229662, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2229662/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/cover/20260428140856.941847-1-charsyam@gmail.com/", "project": { "id": 12, "url": "http://patchwork.ozlabs.org/api/1.1/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": "" }, "msgid": "<20260428140856.941847-1-charsyam@gmail.com>", "date": "2026-04-28T14:08:53", "name": "[v2,0/3] ksmbd: fix connection and durable handle teardown races", "submitter": { "id": 93166, "url": "http://patchwork.ozlabs.org/api/1.1/people/93166/?format=api", "name": "DaeMyung Kang", "email": "charsyam@gmail.com" }, "mbox": "http://patchwork.ozlabs.org/project/linux-cifs-client/cover/20260428140856.941847-1-charsyam@gmail.com/mbox/", "series": [ { "id": 501865, "url": "http://patchwork.ozlabs.org/api/1.1/series/501865/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=501865", "date": "2026-04-28T14:08:55", "name": "ksmbd: fix connection and durable handle teardown races", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/501865/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2229662/comments/", "headers": { "Return-Path": "\n <linux-cifs+bounces-11216-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=jbn354As;\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-11216-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=\"jbn354As\"", "smtp.subspace.kernel.org;\n arc=none smtp.client-ip=209.85.216.46", "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 4g4kyX14nrz1xvV\n\tfor <incoming@patchwork.ozlabs.org>; Wed, 29 Apr 2026 01:35:00 +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 A5D943483ACC\n\tfor <incoming@patchwork.ozlabs.org>; Tue, 28 Apr 2026 14:09:14 +0000 (UTC)", "from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 21AC843E4B4;\n\tTue, 28 Apr 2026 14:09:03 +0000 (UTC)", "from mail-pj1-f46.google.com (mail-pj1-f46.google.com\n [209.85.216.46])\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 AE5ED43E9FF\n\tfor <linux-cifs@vger.kernel.org>; Tue, 28 Apr 2026 14:09:01 +0000 (UTC)", "by mail-pj1-f46.google.com with SMTP id\n 98e67ed59e1d1-35d9b4f93f0so1965581a91.3\n for <linux-cifs@vger.kernel.org>;\n Tue, 28 Apr 2026 07:09:01 -0700 (PDT)", "from ser8.. 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The release is queued\nto a dedicated workqueue because transport teardown can sleep, while\none known last-putter is an RCU callback.\n\nPatch 2 hardens __close_file_table_ids() by taking a transient\nksmbd_file reference, unpublishing from the session idr under ft->lock,\nand doing sleepable preserve/close work outside ft->lock. It also\nmakes the FP_NEW window visible to the opener through\nksmbd_update_fstate().\n\nPatch 2 is scoped to file-table teardown and the FP_NEW publication\nwindow. It does not try to fix durable reconnect rollback on later\nsmb2_open() error paths (and the related post-FP_INITED reference\nwindow in fresh smb2_open). Both already exist before this series\nand need either an explicit unpublish-on-error step or an extra\nsession-owned reference. That is left as follow-up work. The\nFP_NEW -> FP_INITED failure reuses smb2_open()'s existing -ENOENT to\nSTATUS_OBJECT_NAME_INVALID mapping to avoid changing wire behavior in\nthis lifetime fix.\n\nPatch 3 closes two related races in the durable scavenger against any\nwalker that iterates f_ci->m_fp_list (ksmbd_lookup_fd_inode() and the\nshare-mode checks). The scavenger no longer reuses fp->node as a\nscavenger-private collect-list node, takes an explicit transient\nreference under global_ft.lock, and drops both the durable lifetime\nand transient refs with atomic_sub_and_test(2, ...) after the\nm_fp_list unlink so an in-flight m_fp_list walker that snatched fp\nowns the final close cleanly. fp->persistent_id is cleared inside\n__ksmbd_remove_durable_fd() so a delayed final close cannot re-issue\nidr_remove() on a slot that idr_alloc_cyclic() may have already\nre-handed to a new durable handle. __put_fd_final() bypasses the\nper-conn open_files_count decrement when fp is detached from any\nsession table (fp->conn cleared by session_fd_check() at durable\npreserve, paired with the volatile_id clear at unpublish), since the\nwalker that owns the final close in that case runs from an unrelated\nwork->conn whose counter never tracked this durable fp.\n\nThe series is intentionally scoped to lifetime/race fixes and the\nwalker-final-putter regression that the durable scavenger handoff in\npatch 3 newly exposes. Pre-existing reconnect rollback and per-conn\nopen_files_count accounting gaps are left as follow-up work so this\nseries does not have to claim a full durable-reconnect or accounting\ncleanup.\n\nValidation:\n * abrupt-disconnect kmemleak/kprobe A/B for connection release\n * same-session two-tcon DEBUG_LIST/DEBUG_OBJECTS_WORK stress\n * forced durable-preserve sleep-path harness for session teardown\n * KASAN-enabled direct SMB2 coverage for session/tree teardown and\n durable-preserve paths\n * KASAN-enabled direct SMB2 coverage for durable scavenger expiry\n racing with m_fp_list lookups\n * checkpatch --strict for all patches\n * make -j$(nproc) M=fs/smb/server\n\nv1 -> v2:\n * Split the original change into bisectable patches: connection final\n release, session file-table teardown, and durable scavenger races.\n * Keep sleepable session preserve/close work out of ft->lock and make\n the FP_NEW publication race visible through a cleared volatile id.\n * Document that durable reconnect rollback on later smb2_open()\n error paths is a pre-existing follow-up item, and keep the\n existing -ENOENT to STATUS_OBJECT_NAME_INVALID wire mapping for\n this lifetime fix.\n * Avoid reusing fp->node as a temporary durable scavenger list node\n and take a transient reference in the durable scavenger so\n concurrent ksmbd_lookup_fd_inode() walkers cannot UAF on freed fp.\n These two fixes are folded into a single patch because the\n list-head-reuse fix alone leaves a deterministic UAF window for\n m_fp_list walkers; bisecting onto an intermediate state would land\n on a use-after-free that pre-patch chaos merely made less\n reproducible.\n * Clear fp->persistent_id in __ksmbd_remove_durable_fd() so a holder\n that owns the final close after a scavenger removal does not\n re-issue idr_remove() on a persistent id that may have already been\n handed out to a new durable handle.\n * Bypass the per-conn open_files_count decrement in __put_fd_final()\n when fp is detached from any session table, so an m_fp_list walker\n that owns the final close of a scavenged durable fp does not\n underflow an unrelated conn's stats counter.\n * Document the ksmbd_conn_wq lifetime invariant in ksmbd_conn_put()\n instead of guarding with WARN_ON_ONCE, so a violation surfaces as\n a NULL deref rather than a silent leak of the final release.\n\nDaeMyung Kang (3):\n ksmbd: centralize ksmbd_conn final release to plug transport leak\n ksmbd: harden file lifetime during session teardown\n ksmbd: close durable scavenger races against m_fp_list lookups\n\n fs/smb/server/connection.c | 101 +++++++++--\n fs/smb/server/connection.h | 6 +\n fs/smb/server/oplock.c | 7 +-\n fs/smb/server/server.c | 12 ++\n fs/smb/server/smb2pdu.c | 6 +-\n fs/smb/server/vfs_cache.c | 341 ++++++++++++++++++++++++++++++-------\n fs/smb/server/vfs_cache.h | 4 +-\n 7 files changed, 396 insertions(+), 81 deletions(-)" }