cmd/compile, runtime: add checkptr instrumentation for unsafe.Add

Fixes #74431

Change-Id: Id651ea0b82599ccaff8816af0a56ddbb149b6f89
Reviewed-on: https://go-review.googlesource.com/c/go/+/692015
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Auto-Submit: Cuong Manh Le <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: t hepudds <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: cuonglm

src/cmd/compile/internal/walk/expr.go

@@ -131,6 +131,14 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		n := n.(*ir.BinaryExpr)
 		n.X = walkExpr(n.X, init)
 		n.Y = walkExpr(n.Y, init)
+		if n.Op() == ir.OUNSAFEADD && ir.ShouldCheckPtr(ir.CurFunc, 1) {
+			// For unsafe.Add(p, n), just walk "unsafe.Pointer(uintptr(p)+uintptr(n))"
+			// for the side effects of validating unsafe.Pointer rules.
+			x := typecheck.ConvNop(n.X, types.Types[types.TUINTPTR])
+			y := typecheck.Conv(n.Y, types.Types[types.TUINTPTR])
+			conv := typecheck.ConvNop(ir.NewBinaryExpr(n.Pos(), ir.OADD, x, y), types.Types[types.TUNSAFEPTR])
+			walkExpr(conv, init)
+		}
 		return n
 
 	case ir.OUNSAFESLICE:

src/runtime/checkptr_test.go

@@ -35,6 +35,7 @@ func TestCheckPtr(t *testing.T) {
 		{"CheckPtrAlignmentNilPtr", ""},
 		{"CheckPtrArithmetic", "fatal error: checkptr: pointer arithmetic result points to invalid allocation\n"},
 		{"CheckPtrArithmetic2", "fatal error: checkptr: pointer arithmetic result points to invalid allocation\n"},
+		{"CheckPtrArithmeticUnsafeAdd", "fatal error: checkptr: pointer arithmetic result points to invalid allocation\n"},
 		{"CheckPtrSize", "fatal error: checkptr: converted pointer straddles multiple allocations\n"},
 		{"CheckPtrSmall", "fatal error: checkptr: pointer arithmetic computed bad pointer value\n"},
 		{"CheckPtrSliceOK", ""},

src/runtime/testdata/testprog/checkptr.go

@@ -16,6 +16,7 @@ func init() {
 	register("CheckPtrAlignmentNilPtr", CheckPtrAlignmentNilPtr)
 	register("CheckPtrArithmetic", CheckPtrArithmetic)
 	register("CheckPtrArithmetic2", CheckPtrArithmetic2)
+	register("CheckPtrArithmeticUnsafeAdd", CheckPtrArithmeticUnsafeAdd)
 	register("CheckPtrSize", CheckPtrSize)
 	register("CheckPtrSmall", CheckPtrSmall)
 	register("CheckPtrSliceOK", CheckPtrSliceOK)
@@ -79,6 +80,11 @@ func CheckPtrArithmetic2() {
 	sink2 = unsafe.Pointer(uintptr(p) & ^one)
 }
 
+func CheckPtrArithmeticUnsafeAdd() {
+	data := make([]byte, 128)
+	sink2 = (*byte)(unsafe.Add(unsafe.Pointer(unsafe.SliceData(data)), len(data)))
+}
+
 func CheckPtrSize() {
 	p := new(int64)
 	sink2 = p