From 6464920a6e30604cb71d0ecbaa20e35009bd76fb Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Wed, 25 May 2011 12:24:25 +0200
Subject: xen/blkback: don't call vbd_size() if bd_disk is NULL

...because vbd_size() dereferences bd_disk if bd_part is NULL.

Signed-off-by: Laszlo Ersek<lersek@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 3457082..6cc0db1 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -357,14 +357,13 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
 	}
 
 	vbd->bdev = bdev;
-	vbd->size = vbd_sz(vbd);
-
 	if (vbd->bdev->bd_disk == NULL) {
 		DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
 			vbd->pdevice);
 		xen_vbd_free(vbd);
 		return -ENOENT;
 	}
+	vbd->size = vbd_sz(vbd);
 
 	if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
 		vbd->type |= VDISK_CDROM;
-- 
cgit v0.10.2


From 9b83c771214cf6a256ee875050e6eaf320cf7983 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <error27@gmail.com>
Date: Fri, 27 May 2011 09:27:16 +0300
Subject: xen/blkback: potential null dereference in error handling

blkbk->pending_pages can be NULL here so I added a check for it.

Signed-off-by: Dan Carpenter <error27@gmail.com>
[v1: Redid the loop a bit]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index c73910c..5cf2993 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -809,11 +809,13 @@ static int __init xen_blkif_init(void)
  failed_init:
 	kfree(blkbk->pending_reqs);
 	kfree(blkbk->pending_grant_handles);
-	for (i = 0; i < mmap_pages; i++) {
-		if (blkbk->pending_pages[i])
-			__free_page(blkbk->pending_pages[i]);
+	if (blkbk->pending_pages) {
+		for (i = 0; i < mmap_pages; i++) {
+			if (blkbk->pending_pages[i])
+				__free_page(blkbk->pending_pages[i]);
+		}
+		kfree(blkbk->pending_pages);
 	}
-	kfree(blkbk->pending_pages);
 	kfree(blkbk);
 	blkbk = NULL;
 	return rc;
-- 
cgit v0.10.2