Refactor - SyscallInvokeSignedRust::translate_instruction() (#1644)

* Reorders all translate_slice() to the beginning of SyscallInvokeSignedRust::translate_instruction().

* Uses the host slice instead the guest one.

* Reorders consume_compute_meter() to happen before heap allocation.

programs/bpf_loader/src/syscalls/cpi.rs

@@ -428,50 +428,48 @@ impl SyscallInvokeSigned for SyscallInvokeSignedRust {
             addr,
             invoke_context.get_check_aligned(),
         )?;
-
-        check_instruction_size(ix.accounts.len(), ix.data.len(), invoke_context)?;
-
         let account_metas = translate_slice::<AccountMeta>(
             memory_mapping,
             ix.accounts.as_ptr() as u64,
             ix.accounts.len() as u64,
             invoke_context.get_check_aligned(),
         )?;
-        let mut accounts = Vec::with_capacity(ix.accounts.len());
-        #[allow(clippy::needless_range_loop)]
-        for account_index in 0..ix.accounts.len() {
-            #[allow(clippy::indexing_slicing)]
-            let account_meta = &account_metas[account_index];
-            if unsafe {
-                std::ptr::read_volatile(&account_meta.is_signer as *const _ as *const u8) > 1
-                    || std::ptr::read_volatile(&account_meta.is_writable as *const _ as *const u8)
-                        > 1
-            } {
-                return Err(Box::new(InstructionError::InvalidArgument));
-            }
-            accounts.push(account_meta.clone());
-        }
+        let data = translate_slice::<u8>(
+            memory_mapping,
+            ix.data.as_ptr() as u64,
+            ix.data.len() as u64,
+            invoke_context.get_check_aligned(),
+        )?
+        .to_vec();
+
+        check_instruction_size(account_metas.len(), data.len(), invoke_context)?;
 
-        let ix_data_len = ix.data.len() as u64;
         if invoke_context
             .get_feature_set()
             .is_active(&feature_set::loosen_cpi_size_restriction::id())
         {
             consume_compute_meter(
                 invoke_context,
-                (ix_data_len)
+                (data.len() as u64)
                     .checked_div(invoke_context.get_compute_budget().cpi_bytes_per_unit)
                     .unwrap_or(u64::MAX),
             )?;
         }
 
-        let data = translate_slice::<u8>(
-            memory_mapping,
-            ix.data.as_ptr() as u64,
-            ix_data_len,
-            invoke_context.get_check_aligned(),
-        )?
-        .to_vec();
+        let mut accounts = Vec::with_capacity(account_metas.len());
+        #[allow(clippy::needless_range_loop)]
+        for account_index in 0..account_metas.len() {
+            #[allow(clippy::indexing_slicing)]
+            let account_meta = &account_metas[account_index];
+            if unsafe {
+                std::ptr::read_volatile(&account_meta.is_signer as *const _ as *const u8) > 1
+                    || std::ptr::read_volatile(&account_meta.is_writable as *const _ as *const u8)
+                        > 1
+            } {
+                return Err(Box::new(InstructionError::InvalidArgument));
+            }
+            accounts.push(account_meta.clone());
+        }
 
         Ok(StableInstruction {
             accounts: accounts.into(),