aoe: fix use after free in aoedev_by_aoeaddr()

We should return NULL on failure instead of returning a freed pointer.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ed Cashin <ecashin@coraid.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/aoe/aoedev.c

@@ -461,6 +461,7 @@ aoedev_by_aoeaddr(ulong maj, int min, int do_alloc)
 	d->targets = kcalloc(NTARGETS, sizeof(*d->targets), GFP_ATOMIC);
 	if (!d->targets) {
 		kfree(d);
+		d = NULL;
 		goto out;
 	}
 	d->ntargets = NTARGETS;