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 A67C54CCDC7; Fri, 4 Sep 2026 05:43:57 +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=1788500638; cv=none; b=gHN4CJR2Jj6XVk65nmK8Zn++l3zvpfw7dJpJCyLB4JFRK1NXxc4Okf5c0lsXIvQLG7j3esTEO+UWXxj8W25AULXz6REDxXMLOWjbs6JtRDyZAcOEnhsmAq3zZHLVTj8gI4c5sXIk8gHYuHwnoRoqqk1Img1Fo/h7dTwcbG1Rbgs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788500638; c=relaxed/simple; bh=0VJwyd4lNeLxNGfPFHtqc5YLFonvmw1qu+hTAj/puYI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OWMideiJyomtnZZwI0hJWBvwKpzgnScev2YWPGTHW7qkXN2fqlfw3OA08q64bdi8UqeBoWIdgw2f7LS64ZpC6qAn7uLhJP8MGoyWfgZTf4ADfjKxjBxmojZJ2WVh6gmhIADAcU+V51TgYVfYuyiU9cYNEyarR6sbo148RHPNbnk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OqCACb/m; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OqCACb/m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD28A1F00A3D; Fri, 4 Sep 2026 05:43:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788500637; bh=xeLKwPiSreTcb69ysWMdvFXnysAiTx865NZP/TklerY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OqCACb/mZkg/2BRfgjQ8XUA0uG5FjE3C8wJfU1e43PWjV//qG0AYrOhO+KtbZAj5y D8/aLRPr1s2F0JciCLhbsLbxsIfMamOYjamOLklAyTX43LKhcCP4Hq2ik6B5v+ZTgN Qw5uzMlRqP++7d2EZaec7ZTT5lz5xlDfslOgf6Y8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Jeff Layton , Chuck Lever Subject: [PATCH 6.18 128/552] nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke Date: Fri, 4 Sep 2026 06:54:45 +0200 Message-ID: <20260904045751.183089601@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045747.813364717@linuxfoundation.org> References: <20260904045747.813364717@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Layton commit ca94ba36172046be6a694a7986f6931e47ed4d51 upstream. 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: Greg Kroah-Hartman --- fs/nfsd/nfs4layouts.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/fs/nfsd/nfs4layouts.c +++ b/fs/nfsd/nfs4layouts.c @@ -249,11 +249,17 @@ nfsd4_alloc_layout_stateid(struct nfsd4_ nfsd4_init_cb(&ls->ls_recall, clp, &nfsd4_cb_layout_ops, NFSPROC4_CLNT_CB_LAYOUT); - if (parent->sc_type == SC_TYPE_DELEG) + if (parent->sc_type == SC_TYPE_DELEG) { + 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);