Jan Beulich
2010-Feb-04 09:22 UTC
[Xen-devel] [PATCH] linux/blkfront: don''t access freed struct xenbus_device
Unfortunately c/s 983 still wasn''t quite right - there was a reference
to freed memory left from blkfront_closing().
As usual, written against 2.6.32.7 and made apply to the 2.6.18
tree without further testing.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
--- a/drivers/xen/blkfront/blkfront.c 2010-02-04 09:29:42.000000000 +0100
+++ b/drivers/xen/blkfront/blkfront.c 2010-02-04 09:31:52.000000000 +0100
@@ -63,7 +63,7 @@
#define GRANT_INVALID_REF 0
static void connect(struct blkfront_info *);
-static void blkfront_closing(struct xenbus_device *);
+static void blkfront_closing(struct blkfront_info *);
static int blkfront_remove(struct xenbus_device *);
static int talk_to_backend(struct xenbus_device *, struct blkfront_info *);
static int setup_blkring(struct xenbus_device *, struct blkfront_info *);
@@ -302,7 +302,7 @@ static void backend_changed(struct xenbu
xenbus_dev_error(dev, -EBUSY,
"Device in use; refusing to close");
else
- blkfront_closing(dev);
+ blkfront_closing(info);
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,17)
up(&bd->bd_sem);
#else
@@ -387,12 +387,11 @@ static void connect(struct blkfront_info
* the backend. Once is this done, we can switch to Closed in
* acknowledgement.
*/
-static void blkfront_closing(struct xenbus_device *dev)
+static void blkfront_closing(struct blkfront_info *info)
{
- struct blkfront_info *info = dev->dev.driver_data;
unsigned long flags;
- DPRINTK("blkfront_closing: %s removed\n", dev->nodename);
+ DPRINTK("blkfront_closing: %d removed\n", info->vdevice);
if (info->rq == NULL)
goto out;
@@ -414,7 +413,8 @@ static void blkfront_closing(struct xenb
xlvbd_del(info);
out:
- xenbus_frontend_closed(dev);
+ if (info->xbdev)
+ xenbus_frontend_closed(info->xbdev);
}
@@ -429,7 +429,7 @@ static int blkfront_remove(struct xenbus
if(info->users == 0)
kfree(info);
else
- info->is_ready = -1;
+ info->xbdev = NULL;
return 0;
}
@@ -498,7 +498,7 @@ int blkif_open(struct block_device *bd,
{
struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
- if(info->is_ready < 0)
+ if (!info->xbdev)
return -ENODEV;
info->users++;
return 0;
@@ -521,13 +521,13 @@ int blkif_release(struct gendisk *disk,
have ignored this request initially, as the device was
still mounted. */
struct xenbus_device * dev = info->xbdev;
- enum xenbus_state state = xenbus_read_driver_state(dev->otherend);
- if(info->is_ready < 0) {
- blkfront_closing(dev);
+ if (!dev) {
+ blkfront_closing(info);
kfree(info);
- } else if (state == XenbusStateClosing && info->is_ready)
- blkfront_closing(dev);
+ } else if (xenbus_read_driver_state(dev->otherend)
+ == XenbusStateClosing && info->is_ready)
+ blkfront_closing(info);
}
return 0;
}
@@ -920,7 +920,7 @@ int blkfront_is_ready(struct xenbus_devi
{
struct blkfront_info *info = dev->dev.driver_data;
- return info->is_ready > 0;
+ return info->is_ready && info->xbdev;
}
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