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

[Daniel Stodden <daniel.stodden@xxxxxxxxxx>]

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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