Messages in this thread | | | Date | Tue, 1 Aug 2023 12:50:56 -0700 | Subject | Re: [PATCH v3 00/12] Enable Linear Address Space Separation support | From | Sohil Mehta <> |
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On 7/31/2023 3:36 PM, Edgecombe, Rick P wrote: > CET introduces this unusual instruction called WRUSS. It allows you to > make user memory accesses while executing in the kernel. Because of > this special property, the CET shadow stack patches don't toggle > stac/clac while executing this instruction. So I think LASS will need > it to behave more like a normal userspace access from the kernel. > Shadow stack is not upstream yet, so just something to keep in mind for > the future. >
This is a good point. We should definitely test this out to confirm.
But, isn't WRUSS already defined as a user-mode access? So, in theory, a user-mode access to a user address space *should* not be blocked by LASS (even with CPL=0).
Are you suggesting that we might need to do something special for WRUSS with LASS enabled?
Sohil
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