From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: [patch] libertas: fix write past end of array in mesh_id_get() Date: Thu, 10 Mar 2011 18:23:26 +0300 Message-ID: <20110310152326.GA2008@bicker> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "John W. Linville" , libertas-dev@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, kernel-janitors@vger.kernel.org To: Dan Williams , javier@cozybit.com Return-path: Received: from mail-bw0-f46.google.com ([209.85.214.46]:63924 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752220Ab1CJP3V (ORCPT ); Thu, 10 Mar 2011 10:29:21 -0500 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: 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 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; } /**