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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT 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 D9055C282DD for ; Thu, 23 May 2019 19:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFD6D21841 for ; Thu, 23 May 2019 19:08:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558638515; bh=it0I7Gz7nzbyQOCIAFGPR1F82AQBs2kZZi/28FjGoPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sep9kE0U658ZC5MLvtsJBwVtJwrFEgtiIx8s8cbJs42OOdUeeSqqXcds9WSIDNNur r9papWgaJldPQlbuJU5xoqtBeygGgbbDoa0B3FRdtRhDj6N0+kN+L9/uEazEfj61F4 uUvrj878ZSk4rROZ8KBTI+VHC+Mj2+nKH0dqbAi0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731797AbfEWTIe (ORCPT ); Thu, 23 May 2019 15:08:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:41304 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731464AbfEWTIc (ORCPT ); Thu, 23 May 2019 15:08:32 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BDAC02133D; Thu, 23 May 2019 19:08:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558638512; bh=it0I7Gz7nzbyQOCIAFGPR1F82AQBs2kZZi/28FjGoPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tliJiYIIN+4B/nGkV+CN8X3sx7nHbNEQxe21OuJmRFyDaiNtzdx4fvMt9yWz8lS51 MS0tmXtCiv+r781iGzUVel1SZ5d+rDUrSMJHje6jl5PLdclY4nlWm3GD8aN3hXLaGO 8VVJFXNHAucSUY7yFlYIlDd4JPRJLnh0npBKGLjs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christoph Probst , Pavel Shilovsky , Steve French Subject: [PATCH 4.9 16/53] cifs: fix strcat buffer overflow and reduce raciness in smb21_set_oplock_level() Date: Thu, 23 May 2019 21:05:40 +0200 Message-Id: <20190523181713.476317191@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523181710.981455400@linuxfoundation.org> References: <20190523181710.981455400@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 CC: Stable Signed-off-by: Greg Kroah-Hartman --- fs/cifs/smb2ops.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -1413,26 +1413,28 @@ 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); }