sanitizers: Stabilize AddressSanitizer and LeakSanitizer for the Tier 1 targets

[rcvalle]

Add support for specifying stable sanitizers in addition to the existing supported sanitizers, remove the -Zsanitizer unstable option and have only the -Csanitize codegen option, requiring the -Zunstable-options to be passed for using unstable sanitizers, add AddressSanitizer and LeakSanitizer for the Tier 1 targets that support them, and also stabilize the no_sanitize attribute so stable sanitizers can also be selectively disabled for annotated functions.. The tracking issue for stabilizing the sanitizers is #123615. This is part of our work to stabilize support for sanitizers in the Rust compiler. (See our roadmap at https://hackmd.io/@rcvalle/S1Ou9K6H6.)

Stabilization Report

Summary

We would like to propose stabilizing AddressSanitizer and LeakSanitizer for the Tier 1 targets that support them, and stabilize the no_sanitize attribute so stable sanitizers can also be selectively disabled for annotated functions.. This will be done by

• Add support for specifying stable sanitizers in addition to the existing supported sanitizers.
• Removing the -Zsanitizer unstable option and having only the -Csanitize codegen option, and requiring the -Zunstable-options to be passed for using unstable sanitizers.
• Adding these sanitizers to the stable sanitizers.
• Stabilize the no_sanitize attribute.

After stabilizing these sanitizers, the supported sanitizers will look like this:

Target	Supported Sanitizers (Stable)	Supported Sanitizers (Unstable)
aarch64-apple-darwin		address, cfi, thread
aarch64-apple-ios		address, thread
aarch64-apple-ios-macabi		address, leak, thread
aarch64-apple-ios-sim		address, thread
aarch64-apple-visionos		address, thread
aarch64-apple-visionos-sim		address, thread
aarch64-fuchsia		address, cfi, shadow-call-stack
aarch64-linux-android		address, cfi, hwaddress, memtag, shadow-call-stack
aarch64-unknown-freebsd		address, cfi, memory, thread
aarch64-unknown-fuchsia		address, cfi, shadow-call-stack
aarch64-unknown-illumos		address, cfi
aarch64-unknown-linux-gnu	address, leak	cfi, hwaddress, kcfi, memory, memtag, thread
aarch64-unknown-linux-musl		address, cfi, leak, memory, thread
aarch64-unknown-linux-ohos		address, cfi, hwaddress, leak, memory, memtag, thread
aarch64-unknown-none		kcfi, kernel-address
arm-linux-androideabi		address
arm64e-apple-darwin		address, cfi, thread
arm64e-apple-ios		address, thread
armv7-linux-androideabi		address
i586-pc-windows-msvc	address
i586-unknown-linux-gnu	address
i686-linux-android		address
i686-pc-windows-msvc	address
i686-unknown-linux-gnu	address
riscv64-linux-android		address
riscv64gc-unknown-fuchsia		shadow-call-stack
riscv64gc-unknown-none-elf		kernel-address
riscv64imac-unknown-none-elf		kernel-address
s390x-unknown-linux-gnu		address, leak, memory, thread
s390x-unknown-linux-musl		address, leak, memory, thread
thumbv7neon-linux-androideabi		address
x86_64-apple-darwin	address, leak	cfi, thread
x86_64-apple-ios		address, thread
x86_64-apple-ios-macabi		address, leak, thread
x86_64-fuchsia		address, cfi, leak
x86_64-linux-android		address
x86_64-pc-solaris		address, cfi, thread
x86_64-pc-windows-msvc	address
x86_64-unknown-freebsd		address, cfi, memory, thread
x86_64-unknown-fuchsia		address, cfi, leak
x86_64-unknown-illumos		address, cfi, thread
x86_64-unknown-linux-gnu	address, leak	cfi, dataflow, kcfi, memory, safestack, thread
x86_64-unknown-linux-musl		address, cfi, leak, memory, thread
x86_64-unknown-linux-ohos		address, cfi, leak, memory, thread
x86_64-unknown-netbsd		address, cfi, leak, memory, thread
x86_64-unknown-none		kcfi, kernel-address
x86_64h-apple-darwin		address, cfi, leak, thread

The tracking issue for stabilizing the sanitizers is #123615. This is part of our work to stabilize support for sanitizers in the Rust compiler. (See our roadmap at https://hackmd.io/@rcvalle/S1Ou9K6H6.)

Documentation

Documentation will be updated by adding documentation for the -Csanitizer codegen option to the Codegen Options in the The rustc book.

Tests

You may find current and will find additional test cases for the sanitizers in:

• tests/ui/sanitizer
• tests/codegen/sanitizer

Unresolved questions

• Doesn't the sanitizers require rebuilding the Rust Standard Library (i.e., Cargo build-std feature)?
  We will prioritize stabilizing sanitizers that provide incremental value without requiring rebuilding the Rust Standard Library (i.e., Cargo build-std feature). We're also working on Partial compilation using MIR-only rlibs compiler-team#738, which should help with -Zbuild-std.

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[rustbot]

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(See the Target Tier Policy.)

[rcvalle]

r? @davidtwco

[compiler-errors]

I'd like to see tests that exercise things like -Csanitizer=non-existent and -Zsanitizer=non-existent, and also -Zsanitizer=stable-sanitizer¹ (e.g. an x86_64-unknown-linux-gnu test for a stable sanitizer) and -Csanitizer=unstable-sanitizer (I believe you can add a run-make test with a custom target that has no sanitizers enabled for it?)

Footnotes

1. What do we do if we pass -Zsanitizer with a stable sanitizer? Should we error? Presumably not, but I would assume we'd want to at least warn the users that the sanitizer has been stabilized and they should be using -C, just like we do for feature gates. ↩

[tgross35]

Documentation will need an update. Is something like -Csanitizer=address,memory expected to work (like LLVM) ordoes it need to be -Csanitizer=address -Dsanitizer=memory?

[Noratrieb]

This is unusable to most stable Rust users, right? It requires either -Zbuild-std or a custom toolchain with an instrumented standard library. The documentation in the rustc book and the stabilization report/description (which you need to add) should mention this very clearly.

[rustbot]

Some changes occurred in cfg and check-cfg configuration

cc @Urgau

Some changes occurred in tests/ui/sanitizer

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

Some changes occurred in tests/codegen/sanitizer

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

[bors]

☔ The latest upstream changes (presumably #127216) made this pull request unmergeable. Please resolve the merge conflicts.

[workingjubilee]

Regarding the prior issues, #121028 will be fixed by #127168 (PR is enqueued).

[tmiasko]

As far existing bug reports are concerned, for LeakSanitizer we also have #111073. Without replicating clang --export-dynamic link flag, LeakSanitizer fails to initialize on my system as well, although I didn't investigate this further.

I expected we would stabilize this under -C sanitize, so cfg predicate is named sanitize (as opposed to sanitizer). Mentioning in case you would like to synchronize this in one direction or the other before it is stabilized here or in #126158.

[Shnatsel]

The proposed removal of -Zsanitizer could be a problem for tooling that enables sanitizers, chiefly cargo-fuzz and other fuzzers.

It is infeasible for the tooling to keep track of which sanitizers are stabilized for which target in which compiler version, so the new CLI must avoid requiring that.

I understand that the following algorithm would be sufficient for enabling sanitizers across both previous and future compiler versions:

Parse the output of rustc -vV. If the rustc version is greater or equal to the version that stabilized this PR, use -Csanitizer instead of -Zsanitizer. If the rustc version string is greater or equal to the version that stabilized this PR, and either contains nightly or the RUSTC_BOOTSTRAP environment variable is set, append -Zunstable-options.

@rcvalle is that correct? If so, I'll make a draft PR for cargo fuzz so this CLI could be tested out before stabilization.

[Shnatsel]

I've implemented support for the proposed new CLI in cargo fuzz: rust-fuzz/cargo-fuzz#376

It took about ~100 LoC, not counting tests.

This will not support a range of nightly rustc versions on which the version number is set to the one in which the sanitizers are set to stabilize, but this PR is not yet merged. Allowing both -Zsanitizer and -Csanitizer flags, at least for a while, would mitigate that.

[cuviper]

Allowing both -Zsanitizer and -Csanitizer flags, at least for a while, would mitigate that.

It's up to the compiler team to decide, but I think this would be rather atypical for an unstable flag.

[cuviper]

I'm not sure if formal FCP concerns are still open, but I want to raise #127483 regarding global variables. That PR is now adding instrumentation to globals unless they opt out with #[no_sanitize], but that attribute is unstable. So from #127483 (comment), it sounds like stable sanitizers could break ctor and linkme without any stable way to fix those.

[ojeda]

Regarding what @Shnatsel mentioned: for the Linux kernel, we also have to decide which flag(s) to use depending on the version/architecture/configuration, so it would be nice to make it as simple as possible.

Relatedly, one thing we do in the C side (and for other tools too) is to try to compile a dummy file to see if a given compiler supports an option -- it would be nice to have a convenient/proper way to test for that instead. (We also do version testing, e.g. >= 1.79.0).

[BertalanD]

So from #127483 (comment), it sounds like stable sanitizers could break ctor and linkme without any stable way to fix those.

As a dumb little stopgap, I could imagine rustc implicitly treating any variables with a custom link_section specified as having the sanitizers disabled. If people need low-level control over where the linker will place a specific global variable, its size/alignment not matching what's written in the code is probably undesired, so they likely also want #[no_sanitize(address)].

And it wouldn't be too difficult to eventually remove this hack once the attribute is stable. It's just a few crates that have to be changed, link_section is not used much outside the aforementioned ones.

[rcvalle]

Thank you everyone for the patience and the time while I go through all the issues listed here.

One of the things that has been mentioned on the tracking issue for stabilizing the sanitizers (#123615) is the absence of Rust interfaces and FFI bindings for the sanitizers (user) interfaces, so I've been working on this for the past few days and have an early/draft implementation of a create that provides (safe) interfaces and FFI bindings for the sanitizers (user) interfaces (see https://crates.io/crates/sanitizers and https://github.com/rcvalle/rust-crate-sanitizers).

It currently reflects the current state of the sanitizers interfaces API and documentation, and I think the crate and the sanitizers interfaces themselves in LLVM would benefit from some standardization of their API and documentation, and is something I'd like to improve in the future. Any contributions are greatly appreciated!

Regarding stabilizing the sanitizers under -Csanitize instead of -Csanitizer, even though I personally prefer the later (but this is subjective), I think consistency not only between attributes and options, but also between compilers, particularly when there are security implications (i.e., making sure a mitigation is applied throughout across compilers for "mixed binaries"), is very important, and if we want to do it, the right time seems to be when stabilizing it (as we don't provide any guarantees about unstable options). Thus, if nobody opposes I'd like to stabilize the sanitizers under -Csanitize instead of -Csanitizer then.

Regarding the removal of -Zsanitizer, we could keep it both, but as @cuviper said, it's up to the compiler team to decide, and I'd like to hear their thoughts on this. I've a question though, would it be possible to make the cut of whether to use -Zsanitizer or the stable option at the version this PR is first merged, and for this version onwards always include the -Zunstable-options along with the stable option? This would reduce the logic for supporting both unstable and stable sanitizers a lot. What do you think?

[rcvalle]

So from #127483 (comment), it sounds like stable sanitizers could break ctor and linkme without any stable way to fix those.

As a dumb little stopgap, I could imagine rustc implicitly treating any variables with a custom link_section specified as having the sanitizers disabled. If people need low-level control over where the linker will place a specific global variable, its size/alignment not matching what's written in the code is probably undesired, so they likely also want #[no_sanitize(address)].

And it wouldn't be too difficult to eventually remove this hack once the attribute is stable. It's just a few crates that have to be changed, link_section is not used much outside the aforementioned ones.

I think it also makes sense to include the stabilization of the no_sanitize attribute as part of this proposal as well. What do you think?

[davidtwco]

Regarding the removal of -Zsanitizer, we could keep it both, but as @cuviper said, it's up to the compiler team to decide, and I'd like to hear their thoughts on this. I've a question though, would it be possible to make the cut of whether to use -Zsanitizer or the stable option at the version this PR is first merged, and for this version onwards always include the -Zunstable-options along with the stable option? This would reduce the logic for supporting both unstable and stable sanitizers a lot. What do you think?

Keeping only a -C option and using -Zunstable-options for the unstable sanitizers is more consistent with what we do for other options, so I prefer that.

I think it also makes sense to include the stabilization of the no_sanitize attribute as part of this proposal as well. What do you think?

I'm open to this, it's just that there seemed to be more open design questions about the attribute.

[rustbot]

Some changes occurred in src/doc/unstable-book/src/language-features/no-sanitize.md

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

[bors]

☔ The latest upstream changes (presumably #129046) made this pull request unmergeable. Please resolve the merge conflicts.

[rcvalle]

Thank you everyone again for the patience and the time while I go through all the issues listed here. Here are a few updates on the progress about these issues:

• possible ASAN miscompile #121028 was fixed in Use the aligned size for alloca at args/ret when the pass mode is cast #127168 and the fix is being followed up on Use insertvalue and extractvalue instead of memcpy in CastTarget #128969.
• Incompatible ASan runtimes when Rust executable links with C shared library that dynamic links asan runtime #114127 was fixed in Add -Z external-clangrt #121207
  Previously, this had to be worked around by providing empty archives so the hard coded paths passed to the linker did not cause an error and additional archives with the actual runtime libraries could be provided. Thus, preventing the hard coded paths from being passed to the linker seems the right fix to me.
• Unable to link use of hyper_util with -Zsanitizer=address on msvc #124390 is still pending.
• Address sanitiser fails to link on x86_64-apple-darwin nightly toolchain #99428 is still pending.
• AddressSanitizer detects a stack-use-after-scope in Chain::new when optimizations are enabled #98454 seems to be a bug on LLVM. I don't think we should block stabilization on this, but let me know if any of you think otherwise.
• ASan/MSan should call __sanitizer_unaligned_{load,store} functions when performing unaligned reads/writes (TSan already calls equivalents) #81722 is not a bug.
• tests/ui/sanitize/leak.rs fails on Linux with sanitizers = true #111073 is being fixed in sanitizers: Fix tests/ui/sanitize/leak.rs fails on #129621.