[armv8][mpu] Fix undefined behaviour in shifting 8 bit value (#1668)

bentank · web-flow · commit f979a19f8e92 · 2024-07-31T08:06:20.000+02:00
diff --git a/CMSIS/Core/Include/mpu_armv8.h b/CMSIS/Core/Include/mpu_armv8.h
@@ -261,12 +261,13 @@ __STATIC_INLINE void ARM_MPU_SetMemAttrEx(MPU_Type* mpu, uint8_t idx, uint8_t at
   const uint8_t reg = idx / 4U;
   const uint32_t pos = ((idx % 4U) * 8U);
   const uint32_t mask = 0xFFU << pos;
+  const uint32_t val = (uint32_t)attr << pos;
   
   if (reg >= (sizeof(mpu->MAIR) / sizeof(mpu->MAIR[0]))) {
     return; // invalid index
   }
   
-  mpu->MAIR[reg] = ((mpu->MAIR[reg] & ~mask) | ((attr << pos) & mask));
+  mpu->MAIR[reg] = ((mpu->MAIR[reg] & ~mask) | (val & mask));
 }
 
 /** Set the memory attribute encoding.

Original file line number	Diff line number	Diff line change
`@@ -261,12 +261,13 @@ __STATIC_INLINE void ARM_MPU_SetMemAttrEx(MPU_Type* mpu, uint8_t idx, uint8_t at`
`261`	`261`	`const uint8_t reg = idx / 4U;`
`262`	`262`	`const uint32_t pos = ((idx % 4U) * 8U);`
`263`	`263`	`const uint32_t mask = 0xFFU << pos;`
	`264`	`+ const uint32_t val = (uint32_t)attr << pos;`
`264`	`265`
`265`	`266`	`if (reg >= (sizeof(mpu->MAIR) / sizeof(mpu->MAIR[0]))) {`
`266`	`267`	`return; // invalid index`
`267`	`268`	`}`
`268`	`269`
`269`		`- mpu->MAIR[reg] = ((mpu->MAIR[reg] & ~mask) \| ((attr << pos) & mask));`
	`270`	`+ mpu->MAIR[reg] = ((mpu->MAIR[reg] & ~mask) \| (val & mask));`
`270`	`271`	`}`
`271`	`272`
`272`	`273`	`/** Set the memory attribute encoding.`