Fix MXCSR configuration dependent timing #111139
Merged
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
Some data-independent timing vector instructions may have subtle data-dependent timing due to MXCSR configuration; dependent on (potentially secret) data instruction retirement may be delayed by one cycle.
|
r? @thomcc (rustbot has picked a reviewer for you, use r? to override) |
rustbot
added
S-waiting-on-review
|
Hey! It looks like you've submitted a new PR for the library teams! If this PR contains changes to any Examples of
|
|
LGTM |
|
@bors r+ |
bors
added
S-waiting-on-bors
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
May 6, 2023
Rollup of 8 pull requests Successful merges: - rust-lang#109677 (Stabilize raw-dylib, link_ordinal, import_name_type and -Cdlltool) - rust-lang#110780 (rustdoc-search: add slices and arrays to index) - rust-lang#110830 (Add FreeBSD cpuset support to `std::thread::available_concurrency`) - rust-lang#111139 (Fix MXCSR configuration dependent timing) - rust-lang#111239 (Remove unnecessary attribute from a diagnostic) - rust-lang#111246 (forbid escaping bound vars in combine) - rust-lang#111251 (Issue 109502 follow up, remove unnecessary Vec::new() from compile_test()) - rust-lang#111261 (Mark `ErrorGuaranteed` constructor as deprecated so people don't use it) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
Dependent on the (potentially secret) data some vector instructions operate on, and the content in MXCSR, instruction retirement may be delayed by one cycle. This is a potential side channel.
This PR fixes this vulnerability for the
x86_64-fortanix-unknown-sgxplatform by loading MXCSR with0x1fbfthrough anxrstorinstruction when the enclave is entered and executing anlfenceimmediately after. Other changes of the MXCSR happen only when the enclave is about to be exited and no vector instructions will be executed before it will actually do so. Users of EDP who change the MXCSR and do wish to defend against this side channel, will need to implement the software mitigation described here.cc: @jethrogb @monokles