From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DAAADC282E0 for ; Wed, 3 Mar 2021 11:03:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E3F864EDF for ; Wed, 3 Mar 2021 11:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238013AbhCCKwp (ORCPT ); Wed, 3 Mar 2021 05:52:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1581832AbhCBT1O (ORCPT ); Tue, 2 Mar 2021 14:27:14 -0500 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB774C061756 for ; Tue, 2 Mar 2021 07:48:38 -0800 (PST) Received: by fieldses.org (Postfix, from userid 2815) id 59F651C81; Tue, 2 Mar 2021 10:48:38 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 59F651C81 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1614700118; bh=PoU6Jm21uiDYByZZf+xG78ujmB2iDcWgJjiajIuG1Uo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C72+yKsWu/GIDurlAHT/fmdM4HJQmtHnO7IzycvYY9vXxCCb/zmfdIRqrfbYBVb0A jbkOjBTjLLTESF4NHhKsTtWzTYHqK76jnbdGURQnm64YvnvTVdtHl5DPmUufFOwIzX C6NXdBO5XPzejH6c3/Qq+l1S8EgkWwF0d0rGRdUs= Date: Tue, 2 Mar 2021 10:48:38 -0500 From: Bruce Fields To: Chuck Lever Cc: Daniel Kobras , Linux NFS Mailing List Subject: [PATCH] rpc: fix NULL dereference on kmalloc failure Message-ID: <20210302154838.GB2263@fieldses.org> References: <20210226230437.jfgagcq5magzlrtv@tuedko18.puzzle-itc.de> <20210301162820.GB11772@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210301162820.GB11772@fieldses.org> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: "J. Bruce Fields" I think this is unlikely but possible: svc_authenticate sets rq_authop and calls svcauth_gss_accept. The kmalloc(sizeof(*svcdata), GFP_KERNEL) fails, leaving rq_auth_data NULL, and returning SVC_DENIED. This causes svc_process_common to go to err_bad_auth, and eventually call svc_authorise. That calls ->release == svcauth_gss_release, which tries to dereference rq_auth_data. Signed-off-by: J. Bruce Fields --- net/sunrpc/auth_gss/svcauth_gss.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) On Mon, Mar 01, 2021 at 11:28:20AM -0500, Bruce Fields wrote: > Possibly orthogonal to this problem, but: svcauth_gss_release > unconditionally dereferences rqstp->rq_auth_data. Isn't that a NULL > dereference if the kmalloc at the start of svcauth_gss_accept() fails? diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index bd4678db9d76..6dff64374bfe 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1825,11 +1825,14 @@ static int svcauth_gss_release(struct svc_rqst *rqstp) { struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data; - struct rpc_gss_wire_cred *gc = &gsd->clcred; + struct rpc_gss_wire_cred *gc; struct xdr_buf *resbuf = &rqstp->rq_res; int stat = -EINVAL; struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id); + if (!gsd) + goto out; + gc = &gsd->clcred; if (gc->gc_proc != RPC_GSS_PROC_DATA) goto out; /* Release can be called twice, but we only wrap once. */ @@ -1870,10 +1873,10 @@ svcauth_gss_release(struct svc_rqst *rqstp) if (rqstp->rq_cred.cr_group_info) put_group_info(rqstp->rq_cred.cr_group_info); rqstp->rq_cred.cr_group_info = NULL; - if (gsd->rsci) + if (gsd && gsd->rsci) { cache_put(&gsd->rsci->h, sn->rsc_cache); - gsd->rsci = NULL; - + gsd->rsci = NULL; + } return stat; } -- 2.29.2