22 lines
1.0 KiB
Rust
22 lines
1.0 KiB
Rust
// should find the bug even without validation and stacked borrows, but gets masked by optimizations
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// compile-flags: -Zmiri-disable-validation -Zmiri-disable-stacked-borrows -Zmir-opt-level=0
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#[repr(align(256))]
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#[derive(Debug)]
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struct MuchAlign;
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fn main() {
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for _ in 0..10 { // Try many times as this might work by chance.
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let buf = [0u32; 256];
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// `buf` is sufficiently aligned for `layout.align` on a `dyn Debug`, but not
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// for the actual alignment required by `MuchAlign`.
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// We craft a wide reference `&dyn Debug` with the vtable for `MuchAlign`. That should be UB,
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// as the reference is not aligned to its dynamic alignment requirements.
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let mut ptr = &MuchAlign as &dyn std::fmt::Debug;
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// Overwrite the data part of `ptr` so it points to `buf`.
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unsafe { (&mut ptr as *mut _ as *mut *const u8).write(&buf as *const _ as *const u8); }
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// Re-borrow that. This should be UB.
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let _ptr = &*ptr; //~ERROR alignment 256 is required
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}
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}
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