From: Julia Lawall <julia@diku.dk>
Date: Mon, 12 May 2008 13:38:26 +0000 (+0200)
Subject: drivers/net/fs_enet: remove null pointer dereference
X-Git-Tag: v2.6.26-rc4~7^2~1^2~7
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ecc8c066f3cecb55807644a01435084d8ed638a;p=linux-2.6

drivers/net/fs_enet: remove null pointer dereference

The following code appears in the function fs_init_instance in the file drivers/net/fs_enet/fs_enet-main.c.

	if (fep->ops == NULL) {
		printk(KERN_ERR DRV_MODULE_NAME
		       ": %s No matching ops found (%d).\n",
		       ndev->name, fpi->fs_no);
		err = -EINVAL;
		goto err;
	}

This code implies that at the point of err, fep->ops can be NULL, so an
extra test is needed before dereferencing this value.

This problem was found using the following semantic match
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E, E1;
identifier f;
statement S1,S2,S3;
@@

* if (E == NULL)
{
  ... when != if (E == NULL) S1 else S2
      when != E = E1
* E->f
  ... when any
  return ...;
}
else S3
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
---

diff --git a/drivers/net/fs_enet/fs_enet-main.c b/drivers/net/fs_enet/fs_enet-main.c
index 67b4b0728f..a5baaf59ff 100644
--- a/drivers/net/fs_enet/fs_enet-main.c
+++ b/drivers/net/fs_enet/fs_enet-main.c
@@ -1093,7 +1093,7 @@ err:
 		if (registered)
 			unregister_netdev(ndev);
 
-		if (fep != NULL) {
+		if (fep && fep->ops) {
 			(*fep->ops->free_bd)(ndev);
 			(*fep->ops->cleanup_data)(ndev);
 		}