From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 101974195A8 for ; Thu, 9 Jul 2026 17:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783618841; cv=none; b=GC811adrY2OR5LWRKWjmhfCTSrsqGDDTMsqP3ZYm/fwV/ndUf972C6rUZrvYqB9MV7qbXUIzTLba/7EqLjgiU6jJjZ2uTkSxX5p7mcbn19hmOOw5ad8KPZQuUeqdyR1p2yesP4Oj1oxYFA04q8V/xtsjRkAjXvjANy40f6DceXU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783618841; c=relaxed/simple; bh=Bnz0DH+LSldhHkcyXR2kaynlY6v1355RFkpwxlsqFnk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=saalZOXtuDsRUrniwYuAmR1FRPHO2MIDp534u33rorGqkjr6Yl5L7aMnyFlgsli2nWf+Fz7TETlvirAm6leZa0Rxfl2FUY2KAymONaJNC4PUA1oq3PRZpwj3jKcZck+CMWeXIOJCs6KPL+wc3mUhk0dpxIV88O5G8xNanKPJd1E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cfb1pxZ6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cfb1pxZ6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2832C1F00A3D; Thu, 9 Jul 2026 17:40:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783618839; bh=T4mQmBtcEZgche4SQCCmXZcj0Cp2O6lYsK3HIu6Ohu0=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=cfb1pxZ62YXclneA01WwPP/jBGsCnqiTcaRboaP2u86xJRB64gN3FLkC27hc8uca8 i0TgwjpXa/Mv7rhdiRGMBlJL7qjNhLo075awG5e/uN7XIvd6PbVEJhFRmb5XJwUljS VKKz2kvUGPrsRgSNRaba1KGNAMn6UKRj1bWLXfMrzcDv8NCXMsGgXIENyOOAcqxApw qY/lGd4gVWz/ejeKeN0XiqCU8naxDvnlppgTDMSLeWr2ja8QoBqE1Ht/z4nnSt4Ma9 eXeRNFRcBt6oAROj1xAUKZzsVFdvWnlZSflY+u0nzTzWUWXSgjm7TUIzl3LQdVGE7O /SWaF7eYsIccg== From: Chuck Lever Date: Thu, 09 Jul 2026 13:40:24 -0400 Subject: [PATCH v4 1/9] NFSD: Prevent lock owner use-after-free during client teardown Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260709-cel-v4-1-1d519d9be0cb@kernel.org> References: <20260709-cel-v4-0-1d519d9be0cb@kernel.org> In-Reply-To: <20260709-cel-v4-0-1d519d9be0cb@kernel.org> To: Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, Wolfgang Walter , Chuck Lever X-Mailer: b4 0.16-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2595; i=cel@kernel.org; h=from:subject:message-id; bh=Bnz0DH+LSldhHkcyXR2kaynlY6v1355RFkpwxlsqFnk=; b=owEBbQKS/ZANAwAKATNqszNvZn+XAcsmYgBqT90VNDwdVP9G3p2t30JpsxzVCmiMmVVcCJ6CJ me5W8dj4FWJAjMEAAEKAB0WIQQosuWwEobfJDzyPv4zarMzb2Z/lwUCak/dFQAKCRAzarMzb2Z/ l+OPEACaLjjqbTXyftnZZvZ6qSwR+iQFptHvc9OFpDA/iAQb4fdxj2mZpl+afku1eojoRB+6iHz f3/AX54BO1mfxqbTveJNYlZsxA+BtoJcAtjowB2NeHhz3jE9kzO4mu9jgW0oQWmFXCSxu1jr7HD wbjoXn801fN/N+6VnEb8p0vWPgXhDHC2Hp2zTMhFVXJRIvF2FRp8RZLwniQxLwosWFbBws77phg DO8BRms3rlVoh56/6u1T929zhpTmPNw0z5Z+7f/Ud+vH3jjIzknL3QkF+Yw2f2cZSZ9UpeJ8487 fGhLsyfCgw4ztNHfa8eP9zHLOmecrpPlVtSPsh52zOWjPMq6SyGeKNriXSFA69V58gKVO0hCb1z QoqAw/hjM0yEh4kLS0w4FqdJns0Wl81xG7OkrD177gvXrup5+gB7Oiq5FkxdP0Epj9g0sDhjZFX gbg/z2/rFTWRYTZqyEyORnIKOL/Tq9joJJ2j2WJ3r+NOIbotmzW/iYVTpGCZv4OcyadWghheeCl VTzZDMlU+wcCcOO3IUGZXmwuD6UeUdApXxgqgRnHTg89VT/OecgGLzIPjOqCc8iBUMYZQ017pbX fUOvlebALEFEYBVLgC+ovrlLatkXVnVQ3lmDDxRJRCD+TkrxkC7STCcbnhNYcs+kEkGJ06obXJ0 ZCdZgQAE7mI8IlA== X-Developer-Key: i=cel@kernel.org; a=openpgp; fpr=28B2E5B01286DF243CF23EFE336AB3336F667F97 __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock. Reported-by: Wolfgang Walter Closes: https://lore.kernel.org/linux-nfs/6eccafaaaa60651ef091257c3439c46b@stwm.de/ Fixes: 68ef3bc31664 ("nfsd: remove blocked locks on client teardown") Reviewed-by: NeilBrown Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- fs/nfsd/nfs4state.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index a4398dc861a5..e000ed3e96e9 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2758,14 +2758,24 @@ __destroy_client(struct nfs4_client *clp) release_openowner(oo); } for (i = 0; i < OWNER_HASH_SIZE; i++) { - struct nfs4_stateowner *so, *tmp; + struct nfs4_stateowner *so; - list_for_each_entry_safe(so, tmp, &clp->cl_ownerstr_hashtbl[i], - so_strhash) { + spin_lock(&clp->cl_lock); + while (!list_empty(&clp->cl_ownerstr_hashtbl[i])) { + so = list_first_entry(&clp->cl_ownerstr_hashtbl[i], + struct nfs4_stateowner, so_strhash); /* Should be no openowners at this point */ WARN_ON_ONCE(so->so_is_open_owner); + nfs4_get_stateowner(so); + unhash_lockowner_locked(lockowner(so)); + spin_unlock(&clp->cl_lock); + remove_blocked_locks(lockowner(so)); + nfs4_put_stateowner(so); + + spin_lock(&clp->cl_lock); } + spin_unlock(&clp->cl_lock); } nfsd4_return_all_client_layouts(clp); nfsd4_shutdown_copy(clp); -- 2.54.0