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Fix fault_type handling in vm_map_lookup().
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Authored by markj on Dec 4 2019, 8:14 PM.
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Details

Summary

Suppose that the map entry is wired, so that we later assign
fault_type = entry->protection. Suppose further that we jump back to
RetryLookup. Then fault_type will no longer contain the original
fault protection mask.

I think this is mostly harmless from a correctness standpoint. We end
up with a fault_type that is a superset of its correct value. We may
trigger a copy-on-write update to the entry while handling a read fault,
or we may end up returning KERN_PROTECTION_FAILURE for a fault that
should have succeeded if the entry protections change while the map lock
was dropped.

Submitted by: Wuyang Chung <wuyang.chung1@gmail.com>

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rS FreeBSD src repository - subversion
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