Support Rust's stack-protector feature (#1135)

* Support Rust's `stack-protector` feature

* Update changelogs

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - ESP32-S3: Added LCD_CAM I8080 driver (#1086)
 - Allow for splitting of the USB Serial JTAG peripheral into tx/rx components (#1024)
 - `RngCore` trait is implemented (#1122)
+- Support Rust's `stack-protector` feature (#1135)
 
 ### Fixed
 

esp-hal/ld/sections/stack.x

@@ -34,3 +34,10 @@ PROVIDE(_stack_start = ORIGIN(RWDATA) + LENGTH(RWDATA));
 PROVIDE(_stack_start_cpu0 = ORIGIN(RWDATA) + LENGTH(RWDATA));
 
 #ENDIF
+
+/*
+Provide the stack_guard for `stack-protector`
+
+Ideally the offset should be configurable - should be done once we have https://github.com/esp-rs/esp-hal/issues/1111
+*/
+PROVIDE(__stack_chk_guard = _stack_end + 4096);

esp-hal/src/lib.rs

@@ -448,3 +448,30 @@ impl<T, const SIZE: usize> FlashSafeDma<T, SIZE> {
         self.inner
     }
 }
+
+#[cfg(riscv)]
+#[export_name = "hal_main"]
+fn hal_main(a0: usize, a1: usize, a2: usize) -> ! {
+    extern "Rust" {
+        // This symbol will be provided by the user via `#[entry]`
+        fn main(a0: usize, a1: usize, a2: usize) -> !;
+    }
+
+    extern "C" {
+        static mut __stack_chk_guard: u32;
+    }
+
+    unsafe {
+        let stack_chk_guard = core::ptr::addr_of_mut!(__stack_chk_guard);
+        // we _should_ use a random value but we don't have a good source for random
+        // numbers here
+        stack_chk_guard.write_volatile(0xdeadbabe);
+
+        main(a0, a1, a2);
+    }
+}
+
+#[export_name = "__stack_chk_fail"]
+unsafe extern "C" fn stack_chk_fail() {
+    panic!("Stack corruption detected");
+}

esp-hal/src/soc/esp32/mod.rs

@@ -46,6 +46,8 @@ pub unsafe extern "C" fn ESP32Reset() -> ! {
         static mut _rtc_slow_bss_end: u32;
 
         static mut _stack_start_cpu0: u32;
+
+        static mut __stack_chk_guard: u32;
     }
 
     // set stack pointer to end of memory: no need to retain stack up to this point
@@ -58,6 +60,13 @@ pub unsafe extern "C" fn ESP32Reset() -> ! {
     xtensa_lx_rt::zero_bss(&mut _rtc_fast_bss_start, &mut _rtc_fast_bss_end);
     xtensa_lx_rt::zero_bss(&mut _rtc_slow_bss_start, &mut _rtc_slow_bss_end);
 
+    unsafe {
+        let stack_chk_guard = core::ptr::addr_of_mut!(__stack_chk_guard);
+        // we _should_ use a random value but we don't have a good source for random
+        // numbers here
+        stack_chk_guard.write_volatile(0xdeadbabe);
+    }
+
     // continue with default reset handler
     xtensa_lx_rt::Reset();
 }

esp-hal/src/soc/esp32s2/mod.rs

@@ -50,6 +50,8 @@ pub unsafe extern "C" fn ESP32Reset() -> ! {
         static mut _rtc_slow_bss_end: u32;
 
         static mut _stack_start_cpu0: u32;
+
+        static mut __stack_chk_guard: u32;
     }
 
     // set stack pointer to end of memory: no need to retain stack up to this point
@@ -62,6 +64,13 @@ pub unsafe extern "C" fn ESP32Reset() -> ! {
     xtensa_lx_rt::zero_bss(&mut _rtc_fast_bss_start, &mut _rtc_fast_bss_end);
     xtensa_lx_rt::zero_bss(&mut _rtc_slow_bss_start, &mut _rtc_slow_bss_end);
 
+    unsafe {
+        let stack_chk_guard = core::ptr::addr_of_mut!(__stack_chk_guard);
+        // we _should_ use a random value but we don't have a good source for random
+        // numbers here
+        stack_chk_guard.write_volatile(0xdeadbabe);
+    }
+
     // continue with default reset handler
     xtensa_lx_rt::Reset();
 }

esp-hal/src/soc/esp32s3/mod.rs

@@ -85,6 +85,8 @@ pub unsafe extern "C" fn ESP32Reset() -> ! {
         static mut _rtc_slow_bss_end: u32;
 
         static mut _stack_start_cpu0: u32;
+
+        static mut __stack_chk_guard: u32;
     }
 
     // set stack pointer to end of memory: no need to retain stack up to this point
@@ -97,6 +99,13 @@ pub unsafe extern "C" fn ESP32Reset() -> ! {
     xtensa_lx_rt::zero_bss(&mut _rtc_fast_bss_start, &mut _rtc_fast_bss_end);
     xtensa_lx_rt::zero_bss(&mut _rtc_slow_bss_start, &mut _rtc_slow_bss_end);
 
+    unsafe {
+        let stack_chk_guard = core::ptr::addr_of_mut!(__stack_chk_guard);
+        // we _should_ use a random value but we don't have a good source for random
+        // numbers here
+        stack_chk_guard.write_volatile(0xdeadbabe);
+    }
+
     // continue with default reset handler
     xtensa_lx_rt::Reset();
 }

esp-riscv-rt/CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- `start_rust` calls `hal_main` instead of calling user's `main` directly (#1135)
+
 ### Removed
 
 ## 0.6.1 - 2024-01-19

esp-riscv-rt/src/lib.rs

@@ -52,8 +52,7 @@ extern "C" {
 #[export_name = "_start_rust"]
 pub unsafe extern "C" fn start_rust(a0: usize, a1: usize, a2: usize) -> ! {
     extern "Rust" {
-        // This symbol will be provided by the user via `#[entry]`
-        fn main(a0: usize, a1: usize, a2: usize) -> !;
+        fn hal_main(a0: usize, a1: usize, a2: usize) -> !;
 
         fn __post_init();
 
@@ -65,7 +64,7 @@ pub unsafe extern "C" fn start_rust(a0: usize, a1: usize, a2: usize) -> ! {
 
     _setup_interrupts();
 
-    main(a0, a1, a2);
+    hal_main(a0, a1, a2);
 }
 
 /// Registers saved in trap handler