libertas: fix write past end of array in mesh_id_get()

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>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 7 deletions

diff --git a/drivers/net/wireless/libertas/mesh.c b/drivers/net/wireless/libertas/mesh.c
index acf3bf63ee33..9d097b9c8005 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;
 }
 
 /**