Added get_arg to check and transmute opty

Author: geetanshjuneja

src/helpers.rs

@@ -1312,3 +1312,15 @@ pub(crate) fn windows_check_buffer_size((success, len): (bool, u64)) -> u32 {
         u32::try_from(len).unwrap()
     }
 }
+
+pub(crate) fn get_arg<'tcx>(
+    ecx: &mut MiriInterpCx<'tcx>,
+    op: &OpTy<'tcx>,
+    ty: Ty<'tcx>,
+) -> InterpResult<'tcx, OpTy<'tcx>> {
+    let ty_layout = ecx.layout_of(ty)?;
+    if !op.layout.backend_repr.eq_up_to_validity(&ty_layout.backend_repr) {
+        throw_ub_format!("Invalid argument type: ABI mismatch");
+    }
+    op.transmute(ty_layout, ecx)
+}

src/shims/x86/sse42.rs

@@ -5,6 +5,7 @@ use rustc_middle::ty::layout::LayoutOf as _;
 use rustc_span::Symbol;
 use rustc_target::callconv::{Conv, FnAbi};
 
+use crate::helpers::get_arg;
 use crate::*;
 
 /// A bitmask constant for scrutinizing the immediate byte provided
@@ -204,11 +205,11 @@ fn deconstruct_args<'tcx>(
     abi: &FnAbi<'tcx, Ty<'tcx>>,
     args: &[OpTy<'tcx>],
 ) -> InterpResult<'tcx, (OpTy<'tcx>, OpTy<'tcx>, Option<(u64, u64)>, u8)> {
-    let array_layout_fn = |ecx: &mut MiriInterpCx<'tcx>, imm: u8| {
+    let array_ty_fn = |ecx: &mut MiriInterpCx<'tcx>, imm: u8| {
         if imm & USE_WORDS != 0 {
-            ecx.layout_of(Ty::new_array(ecx.tcx.tcx, ecx.tcx.types.u16, 8))
+            Ty::new_array(ecx.tcx.tcx, ecx.tcx.types.u16, 8)
         } else {
-            ecx.layout_of(Ty::new_array(ecx.tcx.tcx, ecx.tcx.types.u8, 16))
+            Ty::new_array(ecx.tcx.tcx, ecx.tcx.types.u8, 16)
         }
     };
 
@@ -230,18 +231,18 @@ fn deconstruct_args<'tcx>(
         let len1 = u64::from(ecx.read_scalar(len1)?.to_u32()?.min(default_len));
         let len2 = u64::from(ecx.read_scalar(len2)?.to_u32()?.min(default_len));
 
-        let array_layout = array_layout_fn(ecx, imm)?;
-        let str1 = str1.transmute(array_layout, ecx)?;
-        let str2 = str2.transmute(array_layout, ecx)?;
+        let array_ty = array_ty_fn(ecx, imm);
+        let str1 = get_arg(ecx, str1, array_ty)?;
+        let str2 = get_arg(ecx, str2, array_ty)?;
 
         interp_ok((str1, str2, Some((len1, len2)), imm))
     } else {
         let [str1, str2, imm] = ecx.check_shim(abi, Conv::C, link_name, args)?;
         let imm = ecx.read_scalar(imm)?.to_u8()?;
 
-        let array_layout = array_layout_fn(ecx, imm)?;
-        let str1 = str1.transmute(array_layout, ecx)?;
-        let str2 = str2.transmute(array_layout, ecx)?;
+        let array_ty = array_ty_fn(ecx, imm);
+        let str1 = get_arg(ecx, str1, array_ty)?;
+        let str2 = get_arg(ecx, str2, array_ty)?;
 
         interp_ok((str1, str2, None, imm))
     }