Merge rust-bitcoin/rust-bitcoin#3328: Add basic `miri` checks

bd8ad1f5e2 Add basic `miri` checks (Martin Habovstiak)
fb5971cc2b Fix UB in `siphash24` (Martin Habovstiak)

Pull request description:

  We have a bit of `unsafe` code in the crates which should really be checked with `miri`. Thus this adds a basic CI check that automatically determines which crates need `miri` checking and checks them. It also makes sure to enable all target features so that SIMD code can be checked as well.

  This doesn't try to do anything fancy with maintainer tools or run task for now, since I just want to test the basic idea.

  Closes #3192

ACKs for top commit:
  storopoli:
    ACK bd8ad1f5e2
  tcharding:
    ACK bd8ad1f5e2
  sanket1729:
    ACK bd8ad1f5e2
  apoelstra:
    ACK bd8ad1f5e2 successfully ran local tests; wow, good find!

Tree-SHA512: a0d33c7851d6d6b288ca8cc1a902f187814dd82e3528c6f8169fdc0ba71991b99451276aaba5e3b6cde6029e09158063d65e48a71d1e01ee20302b9f653584ef

.github/workflows/miri.yml

@@ -0,0 +1,33 @@
+---   # rust-bitcoin CI: If you edit this file please update README.md
+on:   # yamllint disable-line rule:truthy
+  push:
+    branches:
+      - master
+      - 'test-ci/**'
+  pull_request:
+
+name: Miri
+
+jobs:
+  Miri:
+    name: Miri
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Read nightly version"
+        id: read_toolchain
+        run: echo "nightly_version=$(cat nightly-version)" >> $GITHUB_OUTPUT
+      - name: "Select toolchain"
+        uses: dtolnay/rust-toolchain@v1
+        with:
+          toolchain: ${{ steps.read_toolchain.outputs.nightly_version }}
+          components: miri
+      - name: "Setup miri"
+        run: cargo miri setup
+      - name: "Set dependencies"
+        run: cp Cargo-recent.lock Cargo.lock
+      - name: "Run test script"
+        run: ./contrib/test-miri.sh

contrib/test-miri.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -euox pipefail
+
+cd "$(dirname "$0")/.."
+
+. contrib/test_vars.sh
+
+target_features="$(rustc --print target-features | awk '{ if ($1 == "") { exit 0 } if (NR != 1 && $1 != "crt-static") { if (NR == 2) { printf "+%s", $1 } else { printf ",+%s", $1 } } }')"
+
+for crate in $CRATES;
+do
+	# The secp256k1 crate cannot be miri-checked because of FFI, so we have to exclude it
+	if cargo tree --manifest-path "$crate/Cargo.toml" | grep -q secp256k1;
+	then
+		echo "$crate depends on secp256k1, skipping..." >&2
+		continue
+	fi
+	# Running miri is expensive and not needed for crates that don't contain unsafe
+	if RUSTFLAGS="-C target-feature=$target_features -F unsafe-code" cargo check -q --all-features --target x86_64-unknown-linux-gnu 2>/dev/null;
+	then
+		echo "No unsafe code in $crate, skipping..." >&2
+		continue
+	fi
+
+	RUSTFLAGS="-C target-feature=$target_features" RUSTDOCFLAGS="-C target-feature=$target_features" MIRIFLAGS=-Zmiri-backtrace=full cargo miri test --manifest-path "$crate/Cargo.toml" --all-features --target x86_64-unknown-linux-gnu
+done

hashes/src/siphash24.rs

@@ -4,7 +4,7 @@
 
 use core::ops::Index;
 use core::slice::SliceIndex;
-use core::{cmp, mem, ptr};
+use core::{cmp, mem};
 
 use crate::HashEngine as _;
 
@@ -53,13 +53,7 @@ macro_rules! compress {
 macro_rules! load_int_le {
     ($buf:expr, $i:expr, $int_ty:ident) => {{
         debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len());
-        let mut data = 0 as $int_ty;
+        $int_ty::from_le_bytes($buf.get_unchecked($i..($i + mem::size_of::<$int_ty>())).try_into().expect("len is correctly computed using size_of"))
-        ptr::copy_nonoverlapping(
-            $buf.get_unchecked($i),
-            &mut data as *mut _ as *mut u8,
-            mem::size_of::<$int_ty>(),
-        );
-        data.to_le()
     }};
 }
 

nightly-version

@@ -1 +1 @@
-nightly-2024-09-04
+nightly-2024-09-07