Fix asan according to aarch64 48-bit VMA

crates/libafl_asan/.cargo/config.toml

@@ -5,7 +5,6 @@ linker = "i686-linux-gnu-gcc"
 linker = "arm-linux-gnueabi-gcc"
 runner = "qemu-arm -L /usr/arm-linux-gnueabi/"
 
-
 [target.aarch64-unknown-linux-gnu]
 linker = "aarch64-linux-gnu-gcc"
 runner = "qemu-aarch64 -L /usr/aarch64-linux-gnu/"

crates/libafl_asan/Cargo.toml

@@ -33,6 +33,7 @@ default = [
   "mimalloc",
   "test",
   "tracking",
+  "dynamic_layout",
 ]
 ## Enable support for the `dlmalloc` allocator backend
 dlmalloc = ["dep:dlmalloc"]
@@ -58,6 +59,8 @@ mimalloc = ["dep:baby-mimalloc"]
 test = ["dlmalloc", "guest", "libc"]
 ## Enable support for memory tracking
 tracking = []
+## Generate a dynamic shadow layout automatically
+dynamic_layout = []
 
 [dependencies]
 baby-mimalloc = { version = "0.2.1", default-features = false, features = [
@@ -95,6 +98,10 @@ hashbrown = { workspace = true, default-features = false }
 
 [build-dependencies]
 cc = { version = "1.2.51" }
+build-target = "0.8.0"
+libc = "0.2.179"
+rand = "0.9.2"
+page_size = "0.6.0"
 
 [dev-dependencies]
 env_logger = { version = "0.11.6" }

crates/libafl_asan/build.rs

@@ -1,3 +1,264 @@
+use std::{collections::HashMap, env, fs, ops::RangeInclusive, path::Path, sync::LazyLock};
+
+use build_target::{Arch, Os, PointerWidth, target_arch, target_os, target_pointer_width};
+use rand::Rng;
+
+// Default Linux/i386 mapping on i386 machine
+// (addresses starting with 0xc0000000 are reserved
+// for kernel and thus not sanitized):
+// || `[0x38000000, 0xbfffffff]` || HighMem    ||
+// || `[0x27000000, 0x37ffffff]` || HighShadow ||
+// || `[0x24000000, 0x26ffffff]` || ShadowGap  ||
+// || `[0x20000000, 0x23ffffff]` || LowShadow  ||
+// || `[0x00000000, 0x1fffffff]` || LowMem     ||
+const DEFAULT_32B_LAYOUT: TargetShadowLayout = TargetShadowLayout {
+    high_mem: 0x38000000..=0xbfffffff,
+    high_shadow: 0x27000000..=0x37ffffff,
+    shadow_gap: 0x24000000..=0x26ffffff,
+    low_shadow: 0x20000000..=0x23ffffff,
+    low_mem: 0x00000000..=0x1fffffff,
+};
+
+// Typical shadow mapping on Linux/x86_64 with SHADOW_OFFSET == 0x00007fff8000:
+// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
+// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
+// || `[0x00008fff7000, 0x02008fff6fff]` || ShadowGap  ||
+// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
+// || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
+const DEFAULT_64B_LAYOUT: TargetShadowLayout = TargetShadowLayout {
+    high_mem: 0x10007fff8000..=0x7fffffffffff,
+    high_shadow: 0x02008fff7000..=0x10007fff7fff,
+    shadow_gap: 0x00008fff7000..=0x02008fff6fff,
+    low_shadow: 0x00007fff8000..=0x00008fff6fff,
+    low_mem: 0x000000000000..=0x00007fff7fff,
+};
+
+#[expect(clippy::type_complexity)]
+static SPECIFIC_LAYOUTS: LazyLock<HashMap<(Arch, Option<Vma>, Os), TargetShadowLayout>> =
+    LazyLock::new(|| {
+        let mut layouts = HashMap::new();
+
+        // Typical shadow mapping on Linux/x86_64 with SHADOW_OFFSET == 0x00007fff8000:
+        // || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
+        // || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
+        // || `[0x00008fff7000, 0x02008fff6fff]` || ShadowGap  ||
+        // || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
+        // || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
+        layouts.insert((Arch::X86_64, None, Os::Linux), DEFAULT_64B_LAYOUT.clone());
+
+        // Default Linux/i386 mapping on i386 machine
+        // (addresses starting with 0xc0000000 are reserved
+        // for kernel and thus not sanitized):
+        // || `[0x38000000, 0xbfffffff]` || HighMem    ||
+        // || `[0x27000000, 0x37ffffff]` || HighShadow ||
+        // || `[0x24000000, 0x26ffffff]` || ShadowGap  ||
+        // || `[0x20000000, 0x23ffffff]` || LowShadow  ||
+        // || `[0x00000000, 0x1fffffff]` || LowMem     ||
+        layouts.insert((Arch::X86, None, Os::Linux), DEFAULT_32B_LAYOUT.clone());
+
+        // Default Linux/AArch64 (48-bit VMA) mapping:
+        // || `[0x201000000000, 0xffffffffffff]` || HighMem    || 229312GB
+        // || `[0x041200000000, 0x200fffffffff]` || HighShadow || 28664GB
+        // || `[0x001200000000, 0x0411ffffffff]` || ShadowGap  || 4096GB
+        // || `[0x001000000000, 0x0011ffffffff]` || LowShadow  || 8GB
+        // || `[0x000000000000, 0x000fffffffff]` || LowMem     || 64GB
+        layouts.insert(
+            (Arch::AArch64, Some(Vma::Vma48), Os::Linux),
+            TargetShadowLayout {
+                high_mem: 0x201000000000..=0xffffffffffff,
+                high_shadow: 0x041200000000..=0x200fffffffff,
+                shadow_gap: 0x001200000000..=0x0411ffffffff,
+                low_shadow: 0x001000000000..=0x0011ffffffff,
+                low_mem: 0x000000000000..=0x000fffffffff,
+            },
+        );
+
+        layouts
+    });
+
+const LAYOUT_TEMPLATE: &str = r#"
+use crate::GuestAddr;
+use super::ShadowLayout;
+
+#[derive(Debug)]
+pub struct DefaultShadowLayout;
+
+impl ShadowLayout for DefaultShadowLayout {
+    const SHADOW_OFFSET: usize = {shadow_offset};
+    const LOW_MEM_OFFSET: GuestAddr = {low_mem_offset};
+    const LOW_MEM_SIZE: usize = {low_mem_size};
+    const LOW_SHADOW_OFFSET: GuestAddr = {low_shadow_offset};
+    const LOW_SHADOW_SIZE: usize = {low_shadow_size};
+    const HIGH_SHADOW_OFFSET: GuestAddr = {high_shadow_offset};
+    const HIGH_SHADOW_SIZE: usize = {high_shadow_size};
+    const HIGH_MEM_OFFSET: GuestAddr = {high_mem_offset};
+    const HIGH_MEM_SIZE: usize = {high_mem_size};
+
+    const ALLOC_ALIGN_POW: usize = 3;
+    const ALLOC_ALIGN_SIZE: usize = 1 << Self::ALLOC_ALIGN_POW;
+}
+"#;
+
+#[derive(Clone, Debug, Copy, PartialEq, Eq, Hash)]
+pub enum Vma {
+    Vma39,
+    Vma42,
+    Vma47,
+    Vma48,
+    Vma52,
+}
+
+#[derive(Clone, Debug)]
+pub struct TargetShadowLayout {
+    high_mem: RangeInclusive<u64>,
+    high_shadow: RangeInclusive<u64>,
+    shadow_gap: RangeInclusive<u64>,
+    low_shadow: RangeInclusive<u64>,
+    low_mem: RangeInclusive<u64>,
+}
+
+impl TargetShadowLayout {
+    pub fn low_mem_offset(&self) -> String {
+        format!("{:#x}", self.low_mem.start())
+    }
+
+    pub fn low_mem_size(&self) -> String {
+        format!("{:#x}", self.low_mem.clone().count())
+    }
+
+    pub fn low_shadow_offset(&self) -> String {
+        format!("{:#x}", self.low_shadow.start())
+    }
+
+    pub fn low_shadow_size(&self) -> String {
+        format!("{:#x}", self.low_shadow.clone().count())
+    }
+
+    pub fn shadow_gap_offset(&self) -> String {
+        format!("{:#x}", self.shadow_gap.start())
+    }
+
+    pub fn shadow_gap_size(&self) -> String {
+        format!("{:#x}", self.shadow_gap.clone().count())
+    }
+
+    pub fn high_mem_offset(&self) -> String {
+        format!("{:#x}", self.high_mem.start())
+    }
+
+    pub fn high_mem_size(&self) -> String {
+        format!("{:#x}", self.high_mem.clone().count())
+    }
+
+    pub fn high_shadow_offset(&self) -> String {
+        format!("{:#x}", self.high_shadow.start())
+    }
+
+    pub fn high_shadow_size(&self) -> String {
+        format!("{:#x}", self.high_shadow.clone().count())
+    }
+}
+
+fn find_max_vaddr_bits<const NB_TRIES: usize>() -> usize {
+    let mut rng = rand::rng();
+    let page_size = page_size::get();
+
+    assert_eq!(page_size.count_ones(), 1);
+
+    let mut bits_min: usize = page_size.trailing_zeros() as usize; // log2(page_size)
+    let mut bits_max: usize = usize::BITS as usize; // size in bits of max addressable memory
+
+    while bits_min != bits_max {
+        let bits_current = (bits_min + bits_max) / 2;
+
+        let mut is_mappable = false;
+        for _ in 0..NB_TRIES {
+            let current_addr_min = 1usize << (bits_current - 1);
+            let current_addr_max = 1usize << bits_current;
+            let current_addr_sz = current_addr_max - current_addr_min;
+
+            assert_eq!(current_addr_sz % page_size, 0);
+
+            let max_page = current_addr_sz / page_size;
+
+            let rdm_page = rng.random_range(0..max_page);
+
+            let map_addr = current_addr_min + (page_size * rdm_page);
+
+            let map_addr_ptr = unsafe {
+                libc::mmap(
+                    map_addr as *mut libc::c_void,
+                    page_size,
+                    libc::PROT_READ,
+                    libc::MAP_PRIVATE | libc::MAP_ANONYMOUS | libc::MAP_FIXED,
+                    -1,
+                    0,
+                )
+            };
+
+            if map_addr_ptr != (-1isize as *mut libc::c_void) {
+                unsafe {
+                    libc::munmap(map_addr_ptr, page_size);
+                }
+                is_mappable = true;
+                break;
+            }
+        }
+
+        if is_mappable {
+            bits_min = bits_current + 1;
+        } else {
+            bits_max = bits_current;
+        }
+    }
+
+    bits_min
+}
+
+fn get_host_vma() -> Vma {
+    match find_max_vaddr_bits::<8>() {
+        39 => Vma::Vma39,
+        42 => Vma::Vma42,
+        47 => Vma::Vma47,
+        48 => Vma::Vma48,
+        52 => Vma::Vma52,
+        val => {
+            panic!("Dynamic layout does not support VMA with {val} bits")
+        }
+    }
+}
+
+fn guess_vma(arch: &Arch) -> Option<Vma> {
+    match arch {
+        Arch::AArch64 => Some(get_host_vma()),
+        _ => None,
+    }
+}
+
+fn get_layout() -> TargetShadowLayout {
+    let arch = target_arch();
+    let vma = guess_vma(&arch);
+    let os = target_os();
+
+    println!("cargo:warning=Generating layout for environment: {arch} - VMA {vma:?} - {os}.");
+
+    if let Some(specific_layout) = SPECIFIC_LAYOUTS.get(&(arch.clone(), vma, os.clone())) {
+        specific_layout.clone()
+    } else {
+        let (default_layout, nb_bits) = match target_pointer_width() {
+            PointerWidth::U32 => (DEFAULT_32B_LAYOUT.clone(), 32),
+            PointerWidth::U64 => (DEFAULT_64B_LAYOUT.clone(), 64),
+            _ => {
+                panic!("Could not find the right layout for {arch:?} (VMA {vma:?}) {os:?}")
+            }
+        };
+
+        println!("cargo:warning=Using default layout for {nb_bits} bits architectures.");
+
+        default_layout
+    }
+}
+
 fn main() {
     //#[cfg(all(feature = "syscalls", not(target_os = "linux")))]
     println!("cargo:warning=The feature `linux` can only be used on Linux!");
@@ -45,4 +306,22 @@ fn main() {
         .include("cc/include/")
         .file("cc/src/log.c")
         .compile("log");
+
+    let layout = get_layout();
+
+    let gen_layout = LAYOUT_TEMPLATE
+        .to_string()
+        .replace("{shadow_offset}", &layout.low_shadow_offset())
+        .replace("{low_mem_offset}", &layout.low_mem_offset())
+        .replace("{low_mem_size}", &layout.low_mem_size())
+        .replace("{low_shadow_offset}", &layout.low_shadow_offset())
+        .replace("{low_shadow_size}", &layout.low_shadow_size())
+        .replace("{high_shadow_offset}", &layout.high_shadow_offset())
+        .replace("{high_shadow_size}", &layout.high_shadow_size())
+        .replace("{high_mem_offset}", &layout.high_mem_offset())
+        .replace("{high_mem_size}", &layout.high_mem_size());
+
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("gen_layout.rs");
+    fs::write(&dest_path, gen_layout).unwrap();
 }

crates/libafl_asan/libafl_asan_fuzz/fuzz_targets/default_frontend_dlmalloc.rs

@@ -9,10 +9,7 @@ use libafl_asan::{
         frontend::{AllocatorFrontend, default::DefaultFrontend},
     },
     mmap::unix::MmapRegion,
-    shadow::{
-        Shadow,
-        guest::{DefaultShadowLayout, GuestShadow},
-    },
+    shadow::{Shadow, guest::GuestShadow, layout::DefaultShadowLayout},
     tracking::guest::GuestTracking,
 };
 use libfuzzer_sys::fuzz_target;

crates/libafl_asan/libafl_asan_fuzz/fuzz_targets/guest_shadow.rs

@@ -7,7 +7,8 @@ use libafl_asan::{
     mmap::libc::LibcMmap,
     shadow::{
         PoisonType, Shadow,
-        guest::{DefaultShadowLayout, GuestShadow, GuestShadowError},
+        guest::{GuestShadow, GuestShadowError},
+        layout::DefaultShadowLayout,
     },
     symbols::dlsym::{DlSymSymbols, LookupTypeNext},
 };