[SCSI] aacraid: Eliminate use after free
Julia Lawall [Sat, 15 May 2010 09:46:12 +0000 (11:46 +0200)]
The debugging code using the freed structure is moved before the kfree.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@free@
expression E;
position p;
@@
kfree@p(E)

@@
expression free.E, subE<=free.E, E1;
position free.p;
@@

  kfree@p(E)
  ...
(
  subE = E1
|
* E
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/aacraid/commctrl.c

index 9c0c911..1a5bf57 100644 (file)
@@ -655,9 +655,9 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
                                /* Does this really need to be GFP_DMA? */
                                p = kmalloc(usg->sg[i].count,GFP_KERNEL|__GFP_DMA);
                                if(!p) {
-                                       kfree (usg);
-                                       dprintk((KERN_DEBUG"aacraid: Could not allocate SG buffer - size = %d buffer number %d of %d\n",
+                                       dprintk((KERN_DEBUG "aacraid: Could not allocate SG buffer - size = %d buffer number %d of %d\n",
                                          usg->sg[i].count,i,usg->count));
+                                       kfree(usg);
                                        rcode = -ENOMEM;
                                        goto cleanup;
                                }