user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

unstable book: in a sanitizer example, check the code

Browse source 
this uses some # directives to make sure the code works on x86_64, and does not produce errors on other platforms
This commit is contained in:
Folkert de Vries 2025-03-29 17:50:20 +01:00
parent 94722cabf4
commit b301e3aed4
No known key found for this signature in database
GPG key ID: 1F17F6FFD112B97C
1 changed files with 15 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

30
src/doc/unstable-book/src/compiler-flags/sanitizer.md
View file

@ -244,18 +244,16 @@ See the [Clang ControlFlowIntegrity documentation][clang-cfi] for more details.
## Example 1: Redirecting control flow using an indirect branch/call to an invalid destination
```rust,ignore (making doc tests pass cross-platform is hard)
use std::arch::naked_asm;
use std::mem;
```rust
fn add_one(x: i32) -> i32 {
x + 1
}
#[unsafe(naked)]
pub extern "C" fn add_two(x: i32) {
# #[cfg(all(target_os = "linux", target_arch = "x86_64"))]
pub extern "sysv64" fn add_two(x: i32) {
// x + 2 preceded by a landing pad/nop block
naked_asm!(
std::arch::naked_asm!(
"
nop
nop
@ -281,16 +279,18 @@ fn main() {
println!("The answer is: {}", answer);
println!("With CFI enabled, you should not see the next answer");
let f: fn(i32) -> i32 = unsafe {
// Offset 0 is a valid branch/call destination (i.e., the function entry
// point), but offsets 1-8 within the landing pad/nop block are invalid
// branch/call destinations (i.e., within the body of the function).
mem::transmute::<*const u8, fn(i32) -> i32>((add_two as *const u8).offset(5))
};
let next_answer = do_twice(f, 5);
# #[cfg(all(target_os = "linux", target_arch = "x86_64"))] {
println!("With CFI enabled, you should not see the next answer");
let f: fn(i32) -> i32 = unsafe {
// Offset 0 is a valid branch/call destination (i.e., the function entry
// point), but offsets 1-8 within the landing pad/nop block are invalid
// branch/call destinations (i.e., within the body of the function).
std::mem::transmute::<*const u8, fn(i32) -> i32>((add_two as *const u8).offset(5))
};
let next_answer = do_twice(f, 5);
println!("The next answer is: {}", next_answer);
println!("The next answer is: {}", next_answer);
# }
}
```
Fig. 1. Redirecting control flow using an indirect branch/call to an invalid