Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754188AbcDZXOe (ORCPT ); Tue, 26 Apr 2016 19:14:34 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40233 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754097AbcDZXOI (ORCPT ); Tue, 26 Apr 2016 19:14:08 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "J. Bruce Fields" Date: Wed, 27 Apr 2016 01:02:21 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 113/217] nfsd: fix deadlock secinfo+readdir compound In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8426:ae4:c500:9cba:69ae:962d:6167 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1044 Lines: 33 3.16.35-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "J. Bruce Fields" commit 2f6fc056e899bd0144a08da5cacaecbe8997cd74 upstream. nfsd_lookup_dentry exits with the parent filehandle locked. fh_put also unlocks if necessary (nfsd filehandle locking is probably too lenient), so it gets unlocked eventually, but if the following op in the compound needs to lock it again, we can deadlock. A fuzzer ran into this; normal clients don't send a secinfo followed by a readdir in the same compound. Signed-off-by: J. Bruce Fields [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- fs/nfsd/nfs4proc.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -880,6 +880,7 @@ nfsd4_secinfo(struct svc_rqst *rqstp, st &exp, &dentry); if (err) return err; + fh_unlock(&cstate->current_fh); if (dentry->d_inode == NULL) { exp_put(exp); err = nfserr_noent;