All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dan Carpenter <error27@gmail.com>
To: Dan Williams <dcbw@redhat.com>, javier@cozybit.com
Cc: "John W. Linville" <linville@tuxdriver.com>,
	libertas-dev@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [patch] libertas: fix write past end of array in mesh_id_get()
Date: Thu, 10 Mar 2011 15:23:26 +0000	[thread overview]
Message-ID: <20110310152326.GA2008@bicker> (raw)

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 <error27@gmail.com>

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;
 }
 
 /**

WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <error27@gmail.com>
To: Dan Williams <dcbw@redhat.com>, javier@cozybit.com
Cc: "John W. Linville" <linville@tuxdriver.com>,
	libertas-dev@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [patch] libertas: fix write past end of array in mesh_id_get()
Date: Thu, 10 Mar 2011 18:23:26 +0300	[thread overview]
Message-ID: <20110310152326.GA2008@bicker> (raw)

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 <error27@gmail.com>

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;
 }
 
 /**

             reply	other threads:[~2011-03-10 15:23 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-10 15:23 Dan Carpenter [this message]
2011-03-10 15:23 ` [patch] libertas: fix write past end of array in mesh_id_get() Dan Carpenter
2011-03-10 17:02 ` Dan Williams
2011-03-10 17:02   ` Dan Williams

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110310152326.GA2008@bicker \
    --to=error27@gmail.com \
    --cc=dcbw@redhat.com \
    --cc=javier@cozybit.com \
    --cc=kernel-janitors@vger.kernel.org \
    --cc=libertas-dev@lists.infradead.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=linville@tuxdriver.com \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.