Arm provides multiple helpers to clean & invalidate the cache for a given region. This is, for instance, used when allocating guest memory to ensure any writes (such as the ones during scrubbing) have reached memory before handing over the page to a guest.

Unfortunately, the arithmetics in the helpers can overflow and would then result to skip the cache cleaning/invalidation. Therefore there is no guarantee when all the writes will reach the memory.

This undefined behavior was meant to be addressed by XSA-437, but the approach was not sufficient.

Arm provides multiple helpers to clean & invalidate the cache for a given region. This is, for instance, used when allocating guest memory to ensure any writes (such as the ones during scrubbing) have reached memory before handing over the page to a guest.

Unfortunately, the arithmetics in the helpers can overflow and would then result to skip the cache cleaning/invalidation. Therefore there is no guarantee when all the writes will reach the memory.

This undefined behavior was meant to be addressed by XSA-437, but the approach was not sufficient.

Affected: Ubuntu:16.04:LTS: xen, Ubuntu:18.04:LTS: xen, Ubuntu:20.04:LTS: xen, Ubuntu:22.04:LTS: xen, Ubuntu:24.04:LTS: xen, Ubuntu:25.10: xen, Ubuntu:26.10: xen, Ubuntu:26.04:LTS: xen

Arm provides multiple helpers to clean & invalidate the cache for a given region. This is, for instance, used when allocating guest memory to ensure any writes (such as the ones during scrubbing) have reached memory before handing over the page to a guest. Unfortunately, the arithmetics in the helpers can overflow and would then result to skip the cache cleaning/invalidation. Therefore there is no guarantee when all the writes will reach the memory. This undefined behavior was meant to be addressed by XSA-437, but the approach was not sufficient.

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