nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2024-11-25 16:24:46 +00:00
Code Issues Packages Projects Releases Wiki Activity

fix handling of alignment for dyn-sized places

Browse Source
This commit is contained in:
Ralf Jung 2023-07-11 15:50:11 +02:00
parent 124fb1490a
commit e7c6db7d44
3 changed files with 12 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
compiler/rustc_const_eval/src/interpret/place.rs
View File

@ -328,7 +328,8 @@ where
};
let mplace = MemPlace { ptr: ptr.to_pointer(self)?, meta };
// When deref'ing a pointer, the *static* alignment given by the type is what matters.
// `ref_to_mplace` is called on raw pointers even if they don't actually get dereferenced;
// we hence can't call `size_and_align_of` since that asserts more validity than we want.
let align = layout.align.abi;
Ok(MPlaceTy { mplace, layout, align })
}
@ -379,11 +380,12 @@ where
/// Check if this mplace is dereferenceable and sufficiently aligned.
pub fn check_mplace(&self, mplace: MPlaceTy<'tcx, M::Provenance>) -> InterpResult<'tcx> {
let (size, align) = self
let (size, _align) = self
.size_and_align_of_mplace(&mplace)?
.unwrap_or((mplace.layout.size, mplace.layout.align.abi));
assert!(mplace.align <= align, "dynamic alignment less strict than static one?");
let align = if M::enforce_alignment(self).should_check() { align } else { Align::ONE };
// Due to packed places, only `mplace.align` matters.
let align =
if M::enforce_alignment(self).should_check() { mplace.align } else { Align::ONE };
self.check_ptr_access_align(mplace.ptr, size, align, CheckInAllocMsg::DerefTest)?;
Ok(())
}

7
src/tools/miri/tests/fail/unaligned_pointers/dyn_alignment.rs
View File

@ -1,5 +1,6 @@
// should find the bug even without validation and stacked borrows, but gets masked by optimizations
//@compile-flags: -Zmiri-disable-validation -Zmiri-disable-stacked-borrows -Zmir-opt-level=0 -Cdebug-assertions=no
// should find the bug even without, but gets masked by optimizations
//@compile-flags: -Zmiri-disable-stacked-borrows -Zmir-opt-level=0 -Cdebug-assertions=no
//@normalize-stderr-test: "but found [0-9]+" -> "but found $$ALIGN"
#[repr(align(256))]
#[derive(Debug)]
@ -19,6 +20,6 @@ fn main() {
(&mut ptr as *mut _ as *mut *const u8).write(&buf as *const _ as *const u8);
}
// Re-borrow that. This should be UB.
let _ptr = &*ptr; //~ERROR: alignment 256 is required
let _ptr = &*ptr; //~ERROR: required 256 byte alignment
}
}

4
src/tools/miri/tests/fail/unaligned_pointers/dyn_alignment.stderr
View File

@ -1,8 +1,8 @@
error: Undefined Behavior: accessing memory with alignment ALIGN, but alignment ALIGN is required
error: Undefined Behavior: constructing invalid value: encountered an unaligned reference (required 256 byte alignment but found $ALIGN)
--> $DIR/dyn_alignment.rs:LL:CC
|
LL | let _ptr = &*ptr;
| ^^^^^ accessing memory with alignment ALIGN, but alignment ALIGN is required
| ^^^^^ constructing invalid value: encountered an unaligned reference (required 256 byte alignment but found $ALIGN)
|
= 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