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Fix Rust UB problems (#6393)

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* Fix miri problems by assuming alignment is 1 in rust

* Removed is_aligned fn from rust verifier.

* Add back is_aligned, but make it w.r.t. buffer[0]

* touch unused variable

* touch unused variable

* +nightly

* Move Rust miri testing into its own docker

* fix bash

* missing one endian conversion

* fix endianness2

* format stuff

Co-authored-by: Casper Neo <cneo@google.com>
This commit is contained in:
Casper
2021-01-11 15:24:52 -05:00
committed by GitHub
parent 39e115fdb4
commit 408cf58024
17 changed files with 540 additions and 197 deletions
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13
rust/flatbuffers/src/verifier.rs
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@@ -232,12 +232,16 @@ impl<'opts, 'buf> Verifier<'opts, 'buf> {
self.num_tables = 0;
self.num_tables = 0;
}
/// Check that there really is a T in there.
/// Checks `pos` is aligned to T's alignment. This does not mean `buffer[pos]` is aligned w.r.t
/// memory since `buffer: &[u8]` has alignment 1.
///
/// ### WARNING
/// This does not work for flatbuffers-structs as they have alignment 1 according to
/// `core::mem::align_of` but are meant to have higher alignment within a Flatbuffer w.r.t.
/// `buffer[0]`. TODO(caspern).
#[inline]
fn is_aligned<T>(&self, pos: usize) -> Result<()> {
// Safe because we're not dereferencing.
let p = unsafe { self.buffer.as_ptr().add(pos) };
if (p as usize) % std::mem::align_of::<T>() == 0 {
if pos % std::mem::align_of::<T>() == 0 {
Ok(())
} else {
Err(InvalidFlatbuffer::Unaligned {
@@ -259,6 +263,7 @@ impl<'opts, 'buf> Verifier<'opts, 'buf> {
}
Ok(())
}
/// Check that there really is a T in there.
#[inline]
pub fn in_buffer<T>(&mut self, pos: usize) -> Result<()> {
self.is_aligned::<T>(pos)?;