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AUTIA authentication sometimes fails
From: |
Derrick McKee |
Subject: |
AUTIA authentication sometimes fails |
Date: |
Mon, 29 Mar 2021 16:07:20 -0400 |
Hi,
I am running across a scenario where a PAC signed code pointer (using
pacia) sometimes does not successfully authenticate despite the signed
pointer and the salt used to sign the pointer are correctly given to a
autia instruction. Only one particular pointer fails, while others
are correctly authenticated. Unfortunately, I can't provide a simple
use case, because the behavior is part of a running kernel, and all
the pointers involved are kernel space pointers. An example of what I
am seeing (not guaranteeing correct assembly, just a gist):
mov x9, 0xffff800009200000
mov x10, 0x20001
pacia x9, x10 // x9 contains 0xff90800009200000
...
mov x9, 0xff90800009200000
mov x10 0x20001
autia x9, x10 // x9 contains invalid pointer
However, this same code with different pointer values correctly
authenticate. Is there something specific about the kernel and PAC
authentication that I am missing? Thanks.
--
Derrick McKee
Phone: (703) 957-9362
Email: derrick.mckee@gmail.com
- AUTIA authentication sometimes fails,
Derrick McKee <=