QEMU target arch selector via feature flag (#405)

* QEMU target arch selector via feature flag

* fix ci

* fixing ci some mmore

* more ci fixes, defaulting to x86_64 always

* more ci

* i368 -> i386 typo fix

* revert forkserver changes

* trying to fix clippy

* docs

* fixed warnings

* more clippy action

* qemu example arch

* bring back deprecated function I don't know how to replace

* get rid of deprecated feature again'

* builds?i

.github/workflows/build_and_test.yml

@@ -63,7 +63,7 @@ jobs:
     # cargo-hack's --feature-powerset would be nice here but libafl has a too many knobs
     - name: Check each feature
       # Skipping python as it has to be built with the `maturin` tool
-      run: cargo hack check --feature-powerset --depth=2 --exclude-features=agpl,nautilus,python,sancov_pcguard_edges --no-dev-deps
+      run: cargo hack check --feature-powerset --depth=2 --exclude-features=agpl,nautilus,python,sancov_pcguard_edges,arm,aarch64,i386 --no-dev-deps
     # pcguard edges and pcguard hitcounts are not compatible and we need to build them seperately
     - name: Check pcguard edges
       run: cargo check --features=sancov_pcguard_edges

fuzzers/qemu_launcher/Cargo.toml

@@ -16,4 +16,4 @@ debug = true
 
 [dependencies]
 libafl = { path = "../../libafl/" }
-libafl_qemu = { path = "../../libafl_qemu/" }
+libafl_qemu = { path = "../../libafl_qemu/", features = ["x86_64"] }

libafl/src/executors/inprocess.rs

@@ -218,7 +218,6 @@ impl InProcessHandlers {
         }
     }
 
-    #[must_use]
     pub fn new<E, EM, I, OC, OF, OT, S, Z>() -> Result<Self, Error>
     where
         I: Input,

libafl/src/stages/concolic.rs

@@ -246,7 +246,7 @@ fn generate_mutations(iter: impl Iterator<Item = (SymExprRef, SymExpr)>) -> Vec<
                 assert_eq!(bits_to_insert % 8, 0, "can only insert full bytes");
                 let after_len = (u64::from(target.get_size()) / 8) - offset - (bits_to_insert / 8);
                 Some(
-                    std::array::IntoIter::new([
+                    [
                         if offset == 0 {
                             None
                         } else {
@@ -267,7 +267,8 @@ fn generate_mutations(iter: impl Iterator<Item = (SymExprRef, SymExpr)>) -> Vec<
                                 false,
                             ))
                         },
-                    ])
+                    ]
+                    .into_iter()
                     .reduce(|acc: Option<BV>, val: Option<BV>| match (acc, val) {
                         (Some(prev), Some(next)) => Some(prev.concat(&next)),
                         (Some(prev), None) => Some(prev),

libafl_qemu/Cargo.toml

@@ -14,6 +14,14 @@ edition = "2021"
 python = ["pyo3", "pyo3-build-config"]
 default = []
 
+# The following architecture features are mutually exclusive.
+x86_64 = [] # build qemu for x86_64 (default)
+i386 = [] # build qemu for i386
+arm = [] # build qemu for arm
+aarch64 = [] # build qemu for aarch64
+
+clippy = [] # special feature for clippy, don't use in normal projects§
+
 [dependencies]
 libafl = { path = "../libafl", version = "0.7.0" }
 libafl_targets = { path = "../libafl_targets", version = "0.7.0" }

libafl_qemu/build.rs

@@ -11,12 +11,24 @@ fn build_dep_check(tools: &[&str]) {
     }
 }
 
+#[macro_export]
+macro_rules! assert_unique_feature {
+    () => {};
+    ($first:tt $(,$rest:tt)*) => {
+        $(
+            #[cfg(not(feature = "clippy"))] // ignore multiple definition for clippy
+            #[cfg(all(feature = $first, feature = $rest))]
+            compile_error!(concat!("features \"", $first, "\" and \"", $rest, "\" cannot be used together"));
+        )*
+        assert_unique_feature!($($rest),*);
+    }
+}
+
 #[allow(clippy::too_many_lines)]
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=src/asan-giovese.c");
     println!("cargo:rerun-if-changed=src/asan-giovese.h");
-    println!("cargo:rerun-if-env-changed=CPU_TARGET");
     println!("cargo:rerun-if-env-changed=CROSS_CC");
 
     let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
@@ -24,13 +36,40 @@ fn main() {
         return;
     }
 
+    // Make sure we have at least and at most one architecutre feature set
+    // Else, we default to `x86_64` - having a default makes CI easier :)
+    assert_unique_feature!("arm", "aarch64", "i386", "i86_64");
+    #[cfg(not(any(
+        feature = "arm",
+        feature = "aarch64",
+        feature = "i386",
+        feature = "x86_64"
+    )))]
+    println!(
+        "cargo:warning=No architecture feature enabled for libafl_qemu, supported: arm, aarch64, i386, x86_64 - defaulting to x86_64"
+    );
+
+    let cpu_target = if cfg!(feature = "clippy") {
+        // assume x86_64 for clippy
+        "x86_64"
+    } else if cfg!(feature = "arm") {
+        "arm"
+    } else if cfg!(feature = "aarch64") {
+        "aarch64"
+    } else if cfg!(feature = "i386") {
+        "368"
+    } else {
+        // if cfg!(feature = "x86_64") {
+        "x86_64"
+        /*} else {
+        panic!("No architecture feture enabled for libafl_qemu");
+        */
+    };
+
     let jobs = env::var("CARGO_BUILD_JOBS");
-    let cpu_target = env::var("CPU_TARGET").unwrap_or_else(|_| {
-        println!("cargo:warning=CPU_TARGET is not set, default to x86_64");
-        "x86_64".to_owned()
-    });
+
     let cross_cc = env::var("CROSS_CC").unwrap_or_else(|_| {
-        println!("cargo:warning=CROSS_CC is not set, default to cc (things can go wrong if CPU_TARGET is not the host arch)");
+        println!("cargo:warning=CROSS_CC is not set, default to cc (things can go wrong if the selected cpu target ({}) is not the host arch ({}))", cpu_target, env::consts::ARCH);
         "cc".to_owned()
     });
 

libafl_qemu/src/lib.rs

@@ -1,17 +1,40 @@
 use std::env;
 
+#[cfg(feature = "aarch64")]
 pub mod aarch64;
-pub mod arm;
-pub mod i386;
-pub mod x86_64;
-
-#[cfg(cpu_target = "aarch64")]
+#[cfg(all(feature = "aarch64", not(feature = "clippy")))]
 pub use aarch64::*;
-#[cfg(cpu_target = "arm")]
+
+#[cfg(feature = "arm")]
+pub mod arm;
+#[cfg(all(feature = "arm", not(feature = "clippy")))]
 pub use arm::*;
-#[cfg(cpu_target = "i386")]
+
+#[cfg(feature = "i386")]
+pub mod i386;
+#[cfg(all(feature = "i386", not(feature = "clippy")))]
 pub use i386::*;
-#[cfg(cpu_target = "x86_64")]
+
+// We default to x86_64, having a default makes CI easier :)
+#[cfg(any(
+    feature = "x86_64",
+    not(any(
+        feature = "arm",
+        feature = "aarch64",
+        feature = "i386",
+        feature = "x86_64"
+    ))
+))]
+pub mod x86_64;
+#[cfg(any(
+    feature = "x86_64",
+    not(any(
+        feature = "arm",
+        feature = "aarch64",
+        feature = "i386",
+        feature = "x86_64"
+    ))
+))]
 pub use x86_64::*;
 
 pub mod elf;