From: Vasily Averin Subject: [patch 2.6.21-rc3] [smbfs] "double free" memory corruption in smbfs Date: Wed, 14 Mar 2007 15:23:33 +0300 Message-ID: <45F7E945.10406@sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit To: Andrew Morton , Linux Kernel Mailing List , linux-fsdevel@vger.kernel.org, Urban Widmark , devel@openvz.org Return-path: Received: from mailhub.sw.ru ([195.214.233.200]:37305 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161208AbXCNMZW (ORCPT ); Wed, 14 Mar 2007 08:25:22 -0400 Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org smbfs allocates rq_trans2buffer to handle server's multi transaction2 response messages. As struct smb_request may be reused, rq_trans2buffer is freed before each new request. However if last servers's response is not multi but single trans2 message then new rq_trans2buffer is not allocated but last smb_rput still tries to free it again. To prevent this issue rq_trans2buffer pointer should be set to NULL after kfree. Signed-off-by: Vasily Averin --- 2.6.21-rc3/fs/smbfs/request.c 2007-03-13 14:22:53.000000000 +0300 +++ 2.6.21-rc3/fs/smbfs/request.c 2007-03-14 11:44:18.000000000 +0300 @@ -181,6 +181,7 @@ static int smb_setup_request(struct smb_ req->rq_errno = 0; req->rq_fragment = 0; kfree(req->rq_trans2buffer); + req->rq_trans2buffer = NULL; return 0; }