getrandom/utils/
sanitizer.rs

1use core::mem::MaybeUninit;
2
3/// Unpoisons `buf` if MSAN support is enabled.
4///
5/// Most backends do not need to unpoison their output. Rust language- and
6/// library- provided functionality unpoisons automatically. Similarly, libc
7/// either natively supports MSAN and/or MSAN hooks libc-provided functions
8/// to unpoison outputs on success. Only when all of these things are
9/// bypassed do we need to do it ourselves.
10///
11/// The call to unpoison should be done as close to the write as possible.
12/// For example, if the backend partially fills the output buffer in chunks,
13/// each chunk should be unpoisoned individually. This way, the correctness of
14/// the chunking logic can be validated (in part) using MSAN.
15pub unsafe fn unpoison(buf: &mut [MaybeUninit<u8>]) {
16    cfg_if! {
17        if #[cfg(getrandom_msan)] {
18            unsafe extern "C" {
19                fn __msan_unpoison(a: *mut core::ffi::c_void, size: usize);
20            }
21            let a = buf.as_mut_ptr().cast();
22            let size = buf.len();
23            unsafe { __msan_unpoison(a, size) };
24        } else {
25            let _ = buf;
26        }
27    }
28}
getrandom/utils/sanitizer.rs

getrandom/utils/
sanitizer.rs
