From patchwork Wed Jun 1 15:52:22 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 12867002 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5D9ACCA473 for ; Wed, 1 Jun 2022 15:52:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345870AbiFAPw0 (ORCPT ); Wed, 1 Jun 2022 11:52:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353707AbiFAPwZ (ORCPT ); Wed, 1 Jun 2022 11:52:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9DF83377DD for ; Wed, 1 Jun 2022 08:52:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2F1C761500 for ; Wed, 1 Jun 2022 15:52:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E7CEC3411A for ; Wed, 1 Jun 2022 15:52:23 +0000 (UTC) Subject: [PATCH] NFSD: Fix potential use-after-free in nfsd_file_put() From: Chuck Lever To: linux-nfs@vger.kernel.org Date: Wed, 01 Jun 2022 11:52:22 -0400 Message-ID: <165409874221.2508.12828917768712364345.stgit@bazille.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org nfsd_file_put_noref() can free @nf, so don't dereference @nf immediately upon return from nfsd_file_put_noref(). Suggested-by: Trond Myklebust Fixes: 999397926ab3 ("nfsd: Clean up nfsd_file_put()") Signed-off-by: Chuck Lever --- fs/nfsd/filecache.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index d32fcd8ad457..148b25a43caf 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -308,11 +308,12 @@ nfsd_file_put(struct nfsd_file *nf) if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags) == 0) { nfsd_file_flush(nf); nfsd_file_put_noref(nf); - } else { + } else if (nf->nf_file) { nfsd_file_put_noref(nf); - if (nf->nf_file) - nfsd_file_schedule_laundrette(); - } + nfsd_file_schedule_laundrette(); + } else + nfsd_file_put_noref(nf); + if (atomic_long_read(&nfsd_filecache_count) >= NFSD_FILE_LRU_LIMIT) nfsd_file_gc(); }