Add LLVM realtime sanitizer #147935

luca3s · 2025-10-21T07:46:17Z

This is a new attempt at adding the LLVM real-time sanitizer to rust.

Previously this was attempted in rust-lang/rfcs#3766.

Since then the sanitize attribute was introduced in #142681 and it is a lot more flexible than the old no_santize attribute. This allows adding real-time sanitizer without the need for a new attribute, like it was proposed in the RFC. Because i only add a new value to a existing command line flag and to a attribute i don't think an MCP is necessary.

Currently real-time santizer is usable in rust code with the rtsan-standalone crate. This downloads or builds the sanitizer runtime and then links it into the rust binary.

The first commit adds support for more detailed sanitizer information.
The second commit then actually adds real-time sanitizer.
The third adds a warning against using real-time sanitizer with async functions, cloures and blocks because it doesn't behave as expected when used with async functions. I am not sure if this is actually wanted, so i kept it in a seperate commit.
The fourth commit adds the documentation for real-time sanitizer.

rustbot · 2025-10-21T07:46:20Z

compiletest directives have been modified. Please add or update docs for the
new or modified directive in src/doc/rustc-dev-guide/.

Some changes occurred in tests/ui/sanitizer

cc @rcvalle

Some changes occurred in src/tools/compiletest

cc @jieyouxu

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred in src/doc/unstable-book/src/compiler-flags/sanitizer.md

cc @rust-lang/project-exploit-mitigations, @rcvalle

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol, @tshepang

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

rustbot · 2025-10-21T07:46:23Z

r? @petrochenkov

rustbot has assigned @petrochenkov.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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jdonszelmann · 2025-10-21T07:49:32Z

Looks ok from attr parsing pov :)

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

petrochenkov · 2025-10-21T12:29:00Z

This change has a lang component (marking functions a blocking or non-blocking), so I'll send this to lang team first, before reviewing the implementation in detail.

traviscross · 2025-10-22T17:38:16Z

Thanks for checking with us. We talked about this in the lang meeting today. We were OK with this going forward experimentally in nightly.

We talked about how, ahead of stabilization, we'd like to see the feature flags for the individual sanitizers be separate to facilitate our review, as we're likely to want to stabilize these incrementally.

luca3s · 2025-10-30T06:12:21Z

Or do i need to use
@bors cancel

Zalathar · 2025-10-30T06:54:18Z

@bors r- retry

luca3s · 2025-10-30T10:31:14Z

I can now reproduce the failure locally reliably with./x test --doc compiler/rustc_lint_defs. I still don't know why it happens. I have basically the same code in the ui tests as in the doctest and the ui test compiles, while the doctest fails.

@rustbot label +S-waiting-on-author -S-waiting-on-bors

luca3s · 2025-10-30T18:44:14Z

I think this should be fixed now. Thanks @Zalathar and @jieyouxu for the help!

@rustbot ready

petrochenkov · 2025-10-31T14:51:40Z

@bors r+

bors · 2025-10-31T14:51:42Z

📌 Commit 8fb9389 has been approved by petrochenkov

It is now in the queue for this repository.

Add LLVM realtime sanitizer This is a new attempt at adding the [LLVM real-time sanitizer](https://clang.llvm.org/docs/RealtimeSanitizer.html) to rust. Previously this was attempted in rust-lang/rfcs#3766. Since then the `sanitize` attribute was introduced in #142681 and it is a lot more flexible than the old `no_santize` attribute. This allows adding real-time sanitizer without the need for a new attribute, like it was proposed in the RFC. Because i only add a new value to a existing command line flag and to a attribute i don't think an MCP is necessary. Currently real-time santizer is usable in rust code with the [rtsan-standalone](https://crates.io/crates/rtsan-standalone) crate. This downloads or builds the sanitizer runtime and then links it into the rust binary. The first commit adds support for more detailed sanitizer information. The second commit then actually adds real-time sanitizer. The third adds a warning against using real-time sanitizer with async functions, cloures and blocks because it doesn't behave as expected when used with async functions. I am not sure if this is actually wanted, so i kept it in a seperate commit. The fourth commit adds the documentation for real-time sanitizer.

bors · 2025-10-31T14:55:19Z

⌛ Testing commit 8fb9389 with merge 88e2495...

bors · 2025-10-31T15:56:58Z

💔 Test failed - checks-actions

luca3s · 2025-10-31T22:17:59Z

My bootstrap.toml was a bit weird and this in combination with a llvm update lead to x.py ignoring the rtsan tests. So i didn't notice that i used abort_on_error completely wrong. I tested (locally) with an aarch64-apple machine and tests ran and passed.

@rustbot ready

rust-log-analyzer · 2025-10-31T23:39:51Z

The job x86_64-gnu-tools failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

...........................................        (143/143)

======== tests/rustdoc-gui/item-info-overflow.goml ========

`tests/rustdoc-gui/item-info-overflow.goml` item-info-overflow output:
Waiting failed: 30000ms exceeded
stack: TimeoutError: Waiting failed: 30000ms exceeded
    at new WaitTask (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/common/WaitTask.js:50:34)
    at IsolatedWorld.waitForFunction (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/api/Realm.js:25:26)
    at CdpFrame.waitForFunction (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/api/Frame.js:561:43)
    at CdpFrame.<anonymous> (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/util/decorators.js:98:27)
    at CdpPage.waitForFunction (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/api/Page.js:1366:37)
    at runAllCommands (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:418:28)
    at async innerRunTestCode (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:696:21)
    at async innerRunTests (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:633:17)
    at async runTests (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:824:27)


======== tests/rustdoc-gui/search-result-display.goml ========

[WARNING] `tests/rustdoc-gui/search-result-display.goml` line 39: Delta is 0 for "x", maybe try to use `compare-elements-position` instead?

rustbot assigned petrochenkov Oct 21, 2025

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luca3s force-pushed the add-rtsan branch from 1a39a8d to a8fc414 Compare October 21, 2025 07:58

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luca3s commented Oct 21, 2025

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luca3s force-pushed the add-rtsan branch from a8fc414 to 28d5767 Compare October 21, 2025 08:29

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luca3s force-pushed the add-rtsan branch from 28d5767 to 7133d59 Compare October 21, 2025 09:26

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traviscross added the P-lang-drag-1 Lang team prioritization drag level 1. https://rust-lang.zulipchat.com/#narrow/channel/410516-t-lang label Oct 22, 2025

traviscross removed the I-lang-nominated Nominated for discussion during a lang team meeting. label Oct 22, 2025

bors added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Oct 30, 2025

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 30, 2025

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luca3s force-pushed the add-rtsan branch from 2e1fdb4 to 8fb9389 Compare October 30, 2025 11:40

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 30, 2025

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 31, 2025

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bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Oct 31, 2025

luca3s and others added 3 commits October 31, 2025 23:13

add realtime sanitizer

54f96d9

add warning for async

366f3aa

add docs

f2ffe66

luca3s force-pushed the add-rtsan branch from 8fb9389 to f2ffe66 Compare October 31, 2025 22:14

Add LLVM realtime sanitizer #147935

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