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https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html#tymethod.dealloc
Layout must be the same layout that was used to allocate that block of memory.
Box and Vec may not respect the specified alignment of a raw pointer and can cause undefind behavior.
Box
Vec
The code below triggers UB.
use maligned::{align_first, A256}; fn main() { let v: Vec<u8> = align_first::<u8, A256>(1009); assert_eq!(v.as_ptr() as usize % 256, 0); assert_eq!(v.capacity(), 1009); drop(v); }
Run MIRI:
cargo +nightly miri run
Then MIRI complains:
error: Undefined Behavior: incorrect layout on deallocation: alloc1367 has size 1009 and alignment 256, but gave size 1009 and alignment 1 --> /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/alloc.rs:104:14 | 104 | unsafe { __rust_dealloc(ptr, layout.size(), layout.align()) } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ incorrect layout on deallocation: alloc1367 has size 1009 and alignment 256, but gave size 1009 and alignment 1 | = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information = note: inside `std::alloc::dealloc` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/alloc.rs:104:14 = note: inside `<std::alloc::Global as std::alloc::Allocator>::deallocate` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/alloc.rs:239:22 = note: inside `<alloc::raw_vec::RawVec<u8> as std::ops::Drop>::drop` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/raw_vec.rs:500:22 = note: inside `std::intrinsics::drop_in_place::<alloc::raw_vec::RawVec<u8>> - shim(Some(alloc::raw_vec::RawVec<u8>))` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:179:1 = note: inside `std::intrinsics::drop_in_place::<std::vec::Vec<u8>> - shim(Some(std::vec::Vec<u8>))` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:179:1 = note: inside `std::mem::drop::<std::vec::Vec<u8>>` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/mem/mod.rs:882:24 note: inside `main` at src/main.rs:7:5 --> src/main.rs:7:5 | 7 | drop(v); | ^^^^^^^ = note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5 = note: inside `std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys_common/backtrace.rs:125:18 = note: inside closure at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:66:18 = note: inside `std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:259:13 = note: inside `std::panicking::r#try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:379:40 = note: inside `std::panicking::r#try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:343:19 = note: inside `std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:396:14 = note: inside `std::rt::lang_start_internal` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:51:25 = note: inside `std::rt::lang_start::<()>` at /home/nugine/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:65:5
I'm sorry but you may have to yank the previous versions and reconsider the design.
The text was updated successfully, but these errors were encountered:
maligned::align_first
Successfully merging a pull request may close this issue.
https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html#tymethod.dealloc
Layout must be the same layout that was used to allocate that block of memory.
BoxandVecmay not respect the specified alignment of a raw pointer and can cause undefind behavior.The code below triggers UB.
Run MIRI:
Then MIRI complains:
I'm sorry but you may have to yank the previous versions and reconsider the design.
The text was updated successfully, but these errors were encountered: