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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 77C3FC4CECD for ; Fri, 20 Sep 2019 14:25:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51E1620882 for ; Fri, 20 Sep 2019 14:25:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388379AbfITOZO (ORCPT ); Fri, 20 Sep 2019 10:25:14 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36722 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388343AbfITOZN (ORCPT ); Fri, 20 Sep 2019 10:25:13 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iBJqQ-00051C-50; Fri, 20 Sep 2019 15:25:10 +0100 Received: from ben by deadeye with local (Exim 4.92.1) (envelope-from ) id 1iBJqF-0007v5-MH; Fri, 20 Sep 2019 15:24:59 +0100 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, Denis Kirjanov , "Christoph Probst" , "Steve French" , "Pavel Shilovsky" Date: Fri, 20 Sep 2019 15:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 081/132] cifs: fix strcat buffer overflow and reduce raciness in smb21_set_oplock_level() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 3.16.74-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Probst commit 6a54b2e002c9d00b398d35724c79f9fe0d9b38fb upstream. Change strcat to strncpy in the "None" case to fix a buffer overflow when cinode->oplock is reset to 0 by another thread accessing the same cinode. It is never valid to append "None" to any other message. Consolidate multiple writes to cinode->oplock to reduce raciness. Signed-off-by: Christoph Probst Reviewed-by: Pavel Shilovsky Signed-off-by: Steve French Signed-off-by: Ben Hutchings --- fs/cifs/smb2ops.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -1000,26 +1000,28 @@ smb21_set_oplock_level(struct cifsInodeI unsigned int epoch, bool *purge_cache) { char message[5] = {0}; + unsigned int new_oplock = 0; oplock &= 0xFF; if (oplock == SMB2_OPLOCK_LEVEL_NOCHANGE) return; - cinode->oplock = 0; if (oplock & SMB2_LEASE_READ_CACHING_HE) { - cinode->oplock |= CIFS_CACHE_READ_FLG; + new_oplock |= CIFS_CACHE_READ_FLG; strcat(message, "R"); } if (oplock & SMB2_LEASE_HANDLE_CACHING_HE) { - cinode->oplock |= CIFS_CACHE_HANDLE_FLG; + new_oplock |= CIFS_CACHE_HANDLE_FLG; strcat(message, "H"); } if (oplock & SMB2_LEASE_WRITE_CACHING_HE) { - cinode->oplock |= CIFS_CACHE_WRITE_FLG; + new_oplock |= CIFS_CACHE_WRITE_FLG; strcat(message, "W"); } - if (!cinode->oplock) - strcat(message, "None"); + if (!new_oplock) + strncpy(message, "None", sizeof(message)); + + cinode->oplock = new_oplock; cifs_dbg(FYI, "%s Lease granted on inode %p\n", message, &cinode->vfs_inode); }