From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: [patch] libertas: fix write past end of array in mesh_id_get() Date: Thu, 10 Mar 2011 11:02:02 -0600 Message-ID: <1299776524.17443.14.camel@dcbw.foobar.com> References: <20110310152326.GA2008@bicker> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: javier@cozybit.com, "John W. Linville" , libertas-dev@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, kernel-janitors@vger.kernel.org To: Dan Carpenter Return-path: Received: from mx1.redhat.com ([209.132.183.28]:28303 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751606Ab1CJRAv (ORCPT ); Thu, 10 Mar 2011 12:00:51 -0500 In-Reply-To: <20110310152326.GA2008@bicker> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2011-03-10 at 18:23 +0300, Dan Carpenter wrote: > defs.meshie.val.mesh_id is 32 chars long. It's not supposed to be NUL > terminated. This code puts a terminator on the end to make it easier to > print to sysfs. The problem is that if the mesh_id fills the entire > buffer the original code puts the terminator one spot past the end. > > The way the original code was written, there was a check to make sure > that maxlen was less than PAGE_SIZE. Since we know that maxlen is at > most 34 chars, I just removed the check. > > Signed-off-by: Dan Carpenter Acked-by: Dan Williams > diff --git a/drivers/net/wireless/libertas/mesh.c b/drivers/net/wireless/libertas/mesh.c > index acf3bf6..9d097b9 100644 > --- a/drivers/net/wireless/libertas/mesh.c > +++ b/drivers/net/wireless/libertas/mesh.c > @@ -918,7 +918,6 @@ static ssize_t mesh_id_get(struct device *dev, struct device_attribute *attr, > char *buf) > { > struct mrvl_mesh_defaults defs; > - int maxlen; > int ret; > > ret = mesh_get_default_parameters(dev, &defs); > @@ -931,13 +930,11 @@ static ssize_t mesh_id_get(struct device *dev, struct device_attribute *attr, > defs.meshie.val.mesh_id_len = IEEE80211_MAX_SSID_LEN; > } > > - /* SSID not null terminated: reserve room for \0 + \n */ > - maxlen = defs.meshie.val.mesh_id_len + 2; > - maxlen = (PAGE_SIZE > maxlen) ? maxlen : PAGE_SIZE; > + memcpy(buf, defs.meshie.val.mesh_id, defs.meshie.val.mesh_id_len); > + buf[defs.meshie.val.mesh_id_len] = '\n'; > + buf[defs.meshie.val.mesh_id_len + 1] = '\0'; > > - defs.meshie.val.mesh_id[defs.meshie.val.mesh_id_len] = '\0'; > - > - return snprintf(buf, maxlen, "%s\n", defs.meshie.val.mesh_id); > + return defs.meshie.val.mesh_id_len + 1; > } > > /** > -- > To unsubscribe from this list: send the line "unsubscribe linux-wireless" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html