From patchwork Thu Apr 22 22:14:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Disseldorp X-Patchwork-Id: 12219217 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 5448BC433ED for ; Thu, 22 Apr 2021 22:14:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26572611AE for ; Thu, 22 Apr 2021 22:14:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236877AbhDVWOv (ORCPT ); Thu, 22 Apr 2021 18:14:51 -0400 Received: from mx2.suse.de ([195.135.220.15]:48364 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235977AbhDVWOv (ORCPT ); Thu, 22 Apr 2021 18:14:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3F032AFEA for ; Thu, 22 Apr 2021 22:14:15 +0000 (UTC) From: David Disseldorp To: linux-cifs@vger.kernel.org Cc: David Disseldorp Subject: [PATCH] cifs: fix leak in cifs_smb3_do_mount() ctx Date: Fri, 23 Apr 2021 00:14:03 +0200 Message-Id: <20210422221403.13617-1-ddiss@suse.de> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org cifs_smb3_do_mount() calls smb3_fs_context_dup() and then cifs_setup_volume_info(). The latter's subsequent smb3_parse_devname() call overwrites the cifs_sb->ctx->UNC string already dup'ed by smb3_fs_context_dup(), resulting in a leak. E.g. unreferenced object 0xffff888002980420 (size 32): comm "mount", pid 160, jiffies 4294892541 (age 30.416s) hex dump (first 32 bytes): 5c 5c 31 39 32 2e 31 36 38 2e 31 37 34 2e 31 30 \\192.168.174.10 34 5c 72 61 70 69 64 6f 2d 73 68 61 72 65 00 00 4\rapido-share.. backtrace: [<00000000069e12f6>] kstrdup+0x28/0x50 [<00000000b61f4032>] smb3_fs_context_dup+0x127/0x1d0 [cifs] [<00000000c6e3e3bf>] cifs_smb3_do_mount+0x77/0x660 [cifs] [<0000000063467a6b>] smb3_get_tree+0xdf/0x220 [cifs] [<00000000716f731e>] vfs_get_tree+0x1b/0x90 [<00000000491d3892>] path_mount+0x62a/0x910 [<0000000046b2e774>] do_mount+0x50/0x70 [<00000000ca7b64dd>] __x64_sys_mount+0x81/0xd0 [<00000000b5122496>] do_syscall_64+0x33/0x40 [<000000002dd397af>] entry_SYSCALL_64_after_hwframe+0x44/0xae This change is a bandaid until the cifs_setup_volume_info() TODO and error handling issues are resolved. Signed-off-by: David Disseldorp Reviewed-by: Paulo Alcantara (SUSE) --- fs/cifs/cifsfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 5ddd20b62484..34c125798ad3 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -834,6 +834,12 @@ cifs_smb3_do_mount(struct file_system_type *fs_type, goto out; } + /* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */ + kfree(cifs_sb->ctx->UNC); + cifs_sb->ctx->UNC = NULL; + kfree(cifs_sb->ctx->prepath); + cifs_sb->ctx->prepath = NULL; + rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC); if (rc) { root = ERR_PTR(rc);