Use trampoline for kallsyms_lookup_name if CET is enabled on Intel CPUs #47
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
During initialization, the PTEditor kernel module for Linux uses kprobes to get the address for the
kallsyms_lookup_namefunction. However, the address obtained this way does not point to anendbr64orendbr32instruction. On CPUs with Intel CET, where the kernel uses Indirect Branch Tracking, calling this address causes a crash.This commit adds a trampoline for
kallsyms_lookup_name, which allows for calling it safely without having to disable Indirect Branch Tracking. Since setting up this trampoline involves hot-patching code, it the commit also adds helper functions to access CR0 and CR4, which we need to modify to disable access restrictions.