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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 32B5DC004C9 for ; Tue, 7 May 2019 16:13:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0181520825 for ; Tue, 7 May 2019 16:13:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QHZynWd2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726495AbfEGQNt (ORCPT ); Tue, 7 May 2019 12:13:49 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:40358 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726558AbfEGQNr (ORCPT ); Tue, 7 May 2019 12:13:47 -0400 Received: by mail-pl1-f196.google.com with SMTP id b3so8415476plr.7; Tue, 07 May 2019 09:13:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PvouaYjN3Arp+88+2ukjI7BrrRf9lUz+IEKElaRnfEQ=; b=QHZynWd2QYaXvolmJ2TVdMus1VL9YSL+KBfdl3oW1im3eGDEhHXcTHTPr5fHG5NHL1 P1tPTJQBEplq5W+TrTmNGLR3sSvXrZ50RNK8G1LnVoDz5qp8NgfpfahuxzbByan1+1pl LoPJj8bmA6DTi50GOVFqXBA5053BgnXKVU7f3/+qfYOaQ5vlXWrqI4uIh1lhSR5qxe91 0CISQFBxXzuC4yVEIuLmLpx0leHBOfPA6iiH35PNgFMbqvVMeDw36h7Hfbpw6Hp1ZM+T q12fZmmdaPk27jPyUqyyDXVRbIVNsT06SHTmIclL5L9eOR5+2l6jCXKmKSPs4VxFrB1H BkTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PvouaYjN3Arp+88+2ukjI7BrrRf9lUz+IEKElaRnfEQ=; b=YGhFQHxZE8Zg83BYKWnJWPjeAkk+jQgCmQ4iFxI4W+Q9KaqtfyK6Yo4VQbpseO+taN mOSDjryiHGO1eqxj4NysDDYWNHRdKT/nVO9jhM65/n9NqVr9N/80rNitn9RdZnevJjBH jzjhNAbsGwxtWBqtdxuCwhqgVIP8Nw0/xqIGjQvAakdcan4Ymi6s4Y9gHvLLp4Evn1oE e2ZSuQs2Sg15dss0MlXMHKugslnyfZWFAr2PsDIXetgcmueSDDhhFiaAifOUtQ8psPMI gztSyzDWTRwMVwD6/pi9Y20Y4uNpUdCpKqwlKGTUTD5fnHoVmBRw2Jo/SiZiKDAQHmS5 cBmw== X-Gm-Message-State: APjAAAX2MgFMKb9eGWn3q1wu+63tIr/2vNvp+6SYdNDr88/frJR+/zUJ 6rGJNAUQcp8IrYF2sGt/Uhvxjh7ArX7XJdZgSf+nIQ== X-Google-Smtp-Source: APXvYqzwej+/HPo7Bs6aRyGls46/1CQgiFLznL8JZhUc7dAFJOuirFsxCA42mxNCF1VwIn1EexS6Nu9rkXYKvnNMuEk= X-Received: by 2002:a17:902:e00a:: with SMTP id ca10mr10539729plb.18.1557245626111; Tue, 07 May 2019 09:13:46 -0700 (PDT) MIME-Version: 1.0 References: <1557242200-26194-1-git-send-email-kernel@probst.it> In-Reply-To: <1557242200-26194-1-git-send-email-kernel@probst.it> From: Steve French Date: Tue, 7 May 2019 11:13:34 -0500 Message-ID: Subject: Re: [PATCH v2] cifs: fix strcat buffer overflow and reduce raciness in smb21_set_oplock_level() To: Christoph Probst Cc: CIFS , Steve French , samba-technical , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org merged into cifs-2.6.git for-next On Tue, May 7, 2019 at 10:17 AM Christoph Probst via samba-technical wrote: > > 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 > --- > fs/cifs/smb2ops.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c > index c36ff0d..aa61dcf 100644 > --- a/fs/cifs/smb2ops.c > +++ b/fs/cifs/smb2ops.c > @@ -2917,26 +2917,28 @@ smb21_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock, > 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); > } > -- > 2.1.4 > > -- Thanks, Steve