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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLACK,USER_AGENT_GIT autolearn=unavailable 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 4F19EC433DF for ; Tue, 28 Jul 2020 12:41:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 34FD220759 for ; Tue, 28 Jul 2020 12:41:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729852AbgG1Mlk (ORCPT ); Tue, 28 Jul 2020 08:41:40 -0400 Received: from 107-174-27-60-host.colocrossing.com ([107.174.27.60]:35556 "EHLO ozlabs.ru" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1729379AbgG1Mlj (ORCPT ); Tue, 28 Jul 2020 08:41:39 -0400 Received: from fstn1-p1.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id EDB48AE800ED; Tue, 28 Jul 2020 08:38:56 -0400 (EDT) From: Alexey Kardashevskiy To: v9fs-developer@lists.sourceforge.net Cc: Alexey Kardashevskiy , "David S. Miller" , Dominique Martinet , Eric Van Hensbergen , Jakub Kicinski , Latchesar Ionkov , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH kernel] 9p/trans_fd: Check file mode at opening Date: Tue, 28 Jul 2020 22:41:29 +1000 Message-Id: <20200728124129.130856-1-aik@ozlabs.ru> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The "fd" transport layer uses 2 file descriptors passed externally and calls kernel_write()/kernel_read() on these. If files were opened without FMODE_WRITE/FMODE_READ, WARN_ON_ONCE() will fire. This adds file mode checking in p9_fd_open; this returns -EBADF to preserve the original behavior. Found by syzkaller. Signed-off-by: Alexey Kardashevskiy --- net/9p/trans_fd.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 13cd683a658a..62cdfbd01f0a 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -797,6 +797,7 @@ static int parse_opts(char *params, struct p9_fd_opts *opts) static int p9_fd_open(struct p9_client *client, int rfd, int wfd) { + bool perm; struct p9_trans_fd *ts = kzalloc(sizeof(struct p9_trans_fd), GFP_KERNEL); if (!ts) @@ -804,12 +805,16 @@ static int p9_fd_open(struct p9_client *client, int rfd, int wfd) ts->rd = fget(rfd); ts->wr = fget(wfd); - if (!ts->rd || !ts->wr) { + perm = ts->rd && (ts->rd->f_mode & FMODE_READ) && + ts->wr && (ts->wr->f_mode & FMODE_WRITE); + if (!ts->rd || !ts->wr || !perm) { if (ts->rd) fput(ts->rd); if (ts->wr) fput(ts->wr); kfree(ts); + if (!perm) + return -EBADF; return -EIO; } -- 2.17.1