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 9F56F2E8897 for ; Sat, 5 Sep 2026 16:40:49 +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=1788626450; cv=none; b=PwZgAJvYLvudenSMy+HY84dTP/Fxx+Q7sE/LqaWBqU3RMldbuSanjoe6jU+cEWMS/iFdKCPVmIqfZSWx0tl/cgTPuWwp3hW8X119FvAUHPxPA2vnuMBUoDBuMKojuydPDCUqevKpYYjRB5bi1y8lrbklLKQe1eT3jG5ZDnXtP5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788626450; c=relaxed/simple; bh=Bi7uGM4Mau65oeParTbOUtt2bsD05UCg5o6VYJILrMc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uKNiWk0Rw5gKIhW2nE8Y8zVnf5jgHJdFkq6VkUi2tsjZ5yEv2CULOZK8m5D/6vsT91OLKjMtvNXKl80JrNww3Gg6LKjUlfQ8Lq5b/ykwv6C34qtzYPxwIEjOprpaPd6Igx/+GYYeDwtJR0ciKUh6NCX7+ie4zKqpUlRYwEoZoi0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cm1YB+l+; 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="cm1YB+l+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC43A1F00A3A; Sat, 5 Sep 2026 16:40:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788626449; bh=qsEXmR8tgPYw/vubk+K7oduLwLlET0/WSKuriEN8K2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cm1YB+l+HRcxroqkPeBvPfgfWFprVFjr/9kOqUdFGN9rwO5aGqAxi4c7OnhaSTgOr 9bX5LTsvddlN0OccsEdI15rvDVlm3WTHCzV6l1yn1sU0FxCa49TxmT6xgKBNHh0hlz jPazTTWUtr0DZu/OqMRsQ520quhKXI57p3Ubds0RW88C6BkToM/LZ2YNucMTrNgTtu VS/yd7QzwprDemnaLQ/74Zl10GGZH3gDeBUEjBIGK3UqvSxxWAD/Ft5kV+sma0Dt2Q zCB43m/bTcSDd+yg/GhycI2U/r6sTtp6myTdwoGA92HR1GJno1yB95/ItAhh2nbcy4 ZZywPr3MfJBBQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chris Mason , Chuck Lever , Sasha Levin Subject: [PATCH 5.15.y] nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke Date: Sat, 5 Sep 2026 12:40:47 -0400 Message-ID: <20260905164047.457754-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090305-musky-peculiar-c632@gregkh> References: <2026090305-musky-peculiar-c632@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit ca94ba36172046be6a694a7986f6931e47ed4d51 ] nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON. This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window. Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid. Fixes: c5c707f96fc9 ("nfsd: implement pNFS layout recalls") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-7 Reported-by: Chris Mason Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260530-nfsd-fixes-v2-1-f27e8eb4d974@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4layouts.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c index bcf16dd07d488..d0b76aee54f83 100644 --- a/fs/nfsd/nfs4layouts.c +++ b/fs/nfsd/nfs4layouts.c @@ -167,9 +167,12 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid) list_del_init(&ls->ls_perfile); spin_unlock(&fp->fi_lock); - if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls) - vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, (void **)&ls); - nfsd_file_put(ls->ls_file); + if (ls->ls_file) { + if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls) + vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, + (void **)&ls); + nfsd_file_put(ls->ls_file); + } if (ls->ls_recalled) atomic_dec(&ls->ls_stid.sc_file->fi_lo_recalls); @@ -234,11 +237,17 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate, nfsd4_init_cb(&ls->ls_recall, clp, &nfsd4_cb_layout_ops, NFSPROC4_CLNT_CB_LAYOUT); - if (parent->sc_type == NFS4_DELEG_STID) + if (parent->sc_type == NFS4_DELEG_STID) { + spin_lock(&fp->fi_lock); ls->ls_file = nfsd_file_get(fp->fi_deleg_file); - else + spin_unlock(&fp->fi_lock); + } else { ls->ls_file = find_any_file(fp); - BUG_ON(!ls->ls_file); + } + if (!ls->ls_file) { + nfs4_put_stid(stp); + return NULL; + } if (nfsd4_layout_setlease(ls)) { nfs4_put_stid(stp); -- 2.53.0