AP_HAL: use array of UART drivers instead of consecutive variables

Avoids UB-inducing assumption that UART drivers are consecutive in the serial() function.
ArduPilot · Nov 15, 2023 · 8e4070d · 8e4070d
1 parent 784f435
commit 8e4070d
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Showing 2 changed files with 15 additions and 24 deletions.
diff --git a/libraries/AP_HAL/HAL.cpp b/libraries/AP_HAL/HAL.cpp
@@ -15,7 +15,6 @@ HAL::FunCallbacks::FunCallbacks(void (*setup_fun)(void), void (*loop_fun)(void))
 // access serial ports using SERIALn numbering
 AP_HAL::UARTDriver* AP_HAL::HAL::serial(uint8_t sernum) const
 {
-    UARTDriver **uart_array = const_cast<UARTDriver**>(&uartA);
     // this mapping captures the historical use of uartB as SERIAL3
     const uint8_t mapping[] = { 0, 2, 3, 1, 4, 5, 6, 7, 8, 9 };
     static_assert(sizeof(mapping) == num_serial, "num_serial must match mapping");

diff --git a/libraries/AP_HAL/HAL.h b/libraries/AP_HAL/HAL.h
@@ -53,16 +53,17 @@ class AP_HAL::HAL {
         AP_HAL::CANIface** _can_ifaces)
 #endif
         :
-        uartA(_uartA),
-        uartB(_uartB),
-        uartC(_uartC),
-        uartD(_uartD),
-        uartE(_uartE),
-        uartF(_uartF),
-        uartG(_uartG),
-        uartH(_uartH),
-        uartI(_uartI),
-        uartJ(_uartJ),
+        uart_array{
+            _uartA,
+            _uartB,
+            _uartC,
+            _uartD,
+            _uartE,
+            _uartF,
+            _uartG,
+            _uartH,
+            _uartI,
+            _uartJ},
         i2c_mgr(_i2c_mgr),
         spi(_spi),
         wspi(_wspi),
@@ -112,19 +113,6 @@ class AP_HAL::HAL {
 
     virtual void run(int argc, char * const argv[], Callbacks* callbacks) const = 0;
 
-private:
-    // the uartX ports must be contiguous in ram for the serial() method to work
-    AP_HAL::UARTDriver* uartA;
-    AP_HAL::UARTDriver* uartB UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartC UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartD UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartE UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartF UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartG UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartH UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartI UNUSED_PRIVATE_MEMBER;
-    AP_HAL::UARTDriver* uartJ UNUSED_PRIVATE_MEMBER;
-
 public:
     AP_HAL::I2CDeviceManager* i2c_mgr;
     AP_HAL::SPIDeviceManager* spi;
@@ -151,6 +139,10 @@ class AP_HAL::HAL {
 
     static constexpr uint8_t num_serial = 10;
 
+private:
+    AP_HAL::UARTDriver* uart_array[num_serial];
+
+public:
 #if AP_SIM_ENABLED && CONFIG_HAL_BOARD != HAL_BOARD_SITL
     AP_HAL::SIMState *simstate;
 #endif