encoding/binary: on invalid type return -1 from Size

Size is defined as returning -1 if the type is not fixed-size.
Before this CL cases like Size((*[]int)(nil)) would crash.

Fixes #60892

Change-Id: Iee8e20a0aee24b542b78cb4160c3b2c5a3eb02c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/504575
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/src/encoding/binary/binary.go b/src/encoding/binary/binary.go
index 158e3e9d7f..3fb18a7a03 100644
--- a/src/encoding/binary/binary.go
+++ b/src/encoding/binary/binary.go
@@ -479,7 +479,6 @@ func dataSize(v reflect.Value) int {
 		if s := sizeof(v.Type().Elem()); s >= 0 {
 			return s * v.Len()
 		}
-		return -1
 
 	case reflect.Struct:
 		t := v.Type()
@@ -491,8 +490,12 @@ func dataSize(v reflect.Value) int {
 		return size
 
 	default:
-		return sizeof(v.Type())
+		if v.IsValid() {
+			return sizeof(v.Type())
+		}
 	}
+
+	return -1
 }
 
 // sizeof returns the size >= 0 of variables for the given type or -1 if the type is not acceptable.