From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH v2] drivers/net/cxgb3/cxgb3_main.c: prevent reading uninitialized stack memory Date: Thu, 16 Sep 2010 11:54:23 -0400 Message-ID: <20100916155423.GA14318@home.goodmis.org> References: <1284586992.6275.93.camel@dan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: divy@chelsio.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, security@kernel.org To: Dan Rosenberg Return-path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:44740 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754944Ab0IPPy0 (ORCPT ); Thu, 16 Sep 2010 11:54:26 -0400 Content-Disposition: inline In-Reply-To: <1284586992.6275.93.camel@dan> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Sep 15, 2010 at 05:43:12PM -0400, Dan Rosenberg wrote: > Fixed formatting (tabs and line breaks). > > The CHELSIO_GET_QSET_NUM device ioctl allows unprivileged users to read > 4 bytes of uninitialized stack memory, because the "addr" member of the > ch_reg struct declared on the stack in cxgb_extension_ioctl() is not > altered or zeroed before being copied back to the user. This patch > takes care of it. > > Signed-off-by: Dan Rosenberg > > --- linux-2.6.35.4.orig/drivers/net/cxgb3/cxgb3_main.c 2010-08-26 19:47:12.000000000 -0400 > +++ linux-2.6.35.4/drivers/net/cxgb3/cxgb3_main.c 2010-09-14 21:24:34.369511115 -0400 > @@ -2296,6 +2296,8 @@ static int cxgb_extension_ioctl(struct n > case CHELSIO_GET_QSET_NUM:{ > struct ch_reg edata; > > + memset(&edata, 0, sizeof(struct ch_reg)); > + > edata.cmd = CHELSIO_GET_QSET_NUM; > edata.val = pi->nqsets; This is a pretty expensive way to fix it. either... + edata.addr = 0; or: - struct ch_reg edata; + struct ch_reg edata = { + .cmd = CHELSIO_GET_QSET_NUM, + .val = pi->nqsets + }; - edata.cmd = CHELSIO_GET_QSET_NUM; - edata.val = pi->nqsets; If you are worried that the struct ch_reg may grow someday. -- Steve > if (copy_to_user(useraddr, &edata, sizeof(edata))) > >