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[Xen-devel] [PATCH 05 of 10] blkfront: Lock blkfront_info when closing

To: Xen <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] [PATCH 05 of 10] blkfront: Lock blkfront_info when closing
From: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
Date: Thu, 29 Apr 2010 02:19:42 -0000
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Delivery-date: Wed, 28 Apr 2010 19:25:34 -0700
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The bdev .open/.release fops race against backend switches to Closing,
handled by the XenBus thread.

The original code attempted to serialize block device holders and
xenbus only via bd_mutex. This is insufficient, the info->bd pointer
may already be stale (or null) while xenbus tries to bump up the
refcount. Worst case scenario is a null ptr deref.

Protect blkfront_info with a dedicated mutex.

Signed-off-by: Daniel Stodden <daniel.stodden@xxxxxxxxxx>


Attachment: blkfront-xenbus-closing.diff
Description: Text Data

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