Android/Linux: Support msan; unpoison output of getrandom syscall. #463
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None of the tests are testing `getrandom_uninit()` directly, but instead it is marked as covered because `getrandom()` forwards to it. However, this means we're never testing an uninitialized input to `getrandom_uninit()`. Fix that.
briansmith
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If we moved away from using |
I will comment in that issue. In short, keeping the |
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Note that this incorporates the changes in #462. |
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Also note that the tests added in #462 fail when with Memory Sanitizer enabled before these changes, but pass after these changes, using the command line added to the crate-level documentation. |
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Aren't we supposed to check for sanitizers like |
tests/common/mod.rs
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| #[allow(unused_variables)] | ||
| fn check_initialized(buf: &[MaybeUninit<u8>]) { | ||
| #[cfg(feature = "unstable-sanitize")] | ||
| { | ||
| // XXX: `#![feature(cfg_sanitize)]` doesn't enable the feature gate correctly. | ||
| // #[cfg(sanitize = "memory")] | ||
| { | ||
| use core::ffi::c_void; | ||
| extern "C" { | ||
| // void __msan_check_mem_is_initialized(const volatile void *x, size_t size); | ||
| fn __msan_check_mem_is_initialized(x: *const c_void, size: usize); | ||
| } | ||
| unsafe { | ||
| __msan_check_mem_is_initialized(buf.as_ptr().cast::<c_void>(), buf.len()); | ||
| } | ||
| } | ||
| } | ||
| } |
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Instead of this complexity, can we just do something in the huge tests which reads the huge buffer. Then MSAN will fail if we've messed up, but we don't need to have any cfg-specific code in our tests.
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Yes, we could maybe do the same thing we do for the large tests? I didn't want to try understanding what the large test is doing, so this was easier :) Also I was curious about whether __msan_check_mem_is_initialized would work.
Yes, but I couldn't get it to work. You can see that the |
| @@ -52,6 +52,8 @@ rustc-dep-of-std = [ | |||
| "libc/rustc-dep-of-std", | |||
| "wasi/rustc-dep-of-std", | |||
| ] | |||
| # Enable support for sanitizers; Requires Rust feature `cfg_sanitize`. | |||
| unstable-sanitize = [] | |||
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Isn't it better to use a configuration flag for this instead of this crate feature?
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Maybe. The good thing about using a feature flag is that other crates can then trigger it automatically with their own feature flag depending on it. That's what I've been planning to do in ring, for example.
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See the added comment for details.
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PR #467 adds a commit that disables the poison call to show that the new msan CI jobs work. See the job fail at https://github.com/rust-random/getrandom/actions/runs/9423708743/job/25962648547, with output: |
There isn't a bug; I just was missing the feature gate in the integration tests and misread the output. All fixed now. |
This stops using weird include hacks to reuse code. Instead, we move the code to a nomral `tests.rs` file and use helper functions to avoid code duplication. This also simplifies our testing of the custom RNGs. Before, we had to disable the "normal" tests to test the custom RNG. Now, the custom RNG is "good enough" to simply pass the tests. I also added direct testing for the `uninit` methods and verified that ``` RUSTFLAGS="-Zsanitizer=memory" cargo +nightly test -Zbuild-std --target=x86_64-unknown-linux-gnu ``` fails (but passes when #463 is added), so we are actually testing the right stuff here. So this can replace #462 Signed-off-by: Joe Richey <joerichey@google.com>
See the added comment for details.