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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 388B3C282C8 for ; Mon, 28 Jan 2019 16:10:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F40272175B for ; Mon, 28 Jan 2019 16:10:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548691823; bh=yG1I47SHAW1Y9veuNv5imVcFdG2h60Ym3uH0MJ8ZrW4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=uY4xYQzt2i2AIEiMSIYeHeJ2NRriQdMVu/IoLLhyi+OtZcTDfL5DZY0YNi5UrPi5n A6ez7NFGVhr7wuGhDbwrVJzfQlZGI29pFMG8GY46wdH4fiu5tl0LfZCJVqyqewJ7in 8cXek+BIsiYDKOf6RZaMLiLinq8mYwuYGY+oUonE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732768AbfA1QKV (ORCPT ); Mon, 28 Jan 2019 11:10:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:35928 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732747AbfA1QKP (ORCPT ); Mon, 28 Jan 2019 11:10:15 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5EDB62184D; Mon, 28 Jan 2019 16:10:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548691814; bh=yG1I47SHAW1Y9veuNv5imVcFdG2h60Ym3uH0MJ8ZrW4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YOYTJW+CFUAZOm4OQWpJBOpPUfdy6ph+oNPkilAYTkegamU6l+PKkhc9l8Jy051AY PdZQSlA3td6DdtQva2wdWUzxYxYaZ39SHUXFjpMuKQv3jaiDnYzAW0lonWeIqcGbn6 1sYD2jf2DXXfQcD5+lyreYMt/+DSxc4/Pr+iWcU4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ronnie Sahlberg , Steve French , Sasha Levin , linux-cifs@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 226/258] cifs: check ntwrk_buf_start for NULL before dereferencing it Date: Mon, 28 Jan 2019 10:58:52 -0500 Message-Id: <20190128155924.51521-226-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128155924.51521-1-sashal@kernel.org> References: <20190128155924.51521-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ronnie Sahlberg [ Upstream commit 59a63e479ce36a3f24444c3a36efe82b78e4a8e0 ] RHBZ: 1021460 There is an issue where when multiple threads open/close the same directory ntwrk_buf_start might end up being NULL, causing the call to smbCalcSize later to oops with a NULL deref. The real bug is why this happens and why this can become NULL for an open cfile, which should not be allowed. This patch tries to avoid a oops until the time when we fix the underlying issue. Signed-off-by: Ronnie Sahlberg Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/cifs/readdir.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index e169e1a5fd35..3925a7bfc74d 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -655,7 +655,14 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, /* scan and find it */ int i; char *cur_ent; - char *end_of_smb = cfile->srch_inf.ntwrk_buf_start + + char *end_of_smb; + + if (cfile->srch_inf.ntwrk_buf_start == NULL) { + cifs_dbg(VFS, "ntwrk_buf_start is NULL during readdir\n"); + return -EIO; + } + + end_of_smb = cfile->srch_inf.ntwrk_buf_start + server->ops->calc_smb_size( cfile->srch_inf.ntwrk_buf_start, server); -- 2.19.1