| Description: | The dispatch_discard_io function in drivers/block/xen-blkback/blkback.c in the Xen blkback implementation in the Linux kernel before 3.10.5 allows guest OS users to cause a denial of service (data loss) via filesystem write operations on a read-only disk that supports the (1) BLKIF_OP_DISCARD (aka discard or TRIM) or (2) SCSI UNMAP feature. A flaw was discovered in the Xen subsystem of the Linux kernel when it provides read-only access to a disk that supports TRIM or SCSI UNMAP to a guest OS. A privileged user in the guest OS could exploit this flaw to destroy data on the disk, even though the guest OS should not be able to write to the disk.
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