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 <[email protected]>

drivers/net/wireless/libertas/mesh.c +4 -8

index acf3bf6..9d097b9 100644
@@ -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;
 }
 
 /**
--

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