From b41185a68f2ec8c492a7dbec1a6bf65f29b0843a Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Fri, 20 Mar 2015 22:33:40 +0100
Subject: rlp: fix nil pointer decoding

The generic pointer decoder did not advance the input position
for empty values. This can lead to strange issues and even
infinite loops.
---
 rlp/decode.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'rlp/decode.go')

diff --git a/rlp/decode.go b/rlp/decode.go
index 6d7e670c2..0e99d9caa 100644
--- a/rlp/decode.go
+++ b/rlp/decode.go
@@ -367,7 +367,12 @@ func makePtrDecoder(typ reflect.Type) (decoder, error) {
 	dec := func(s *Stream, val reflect.Value) (err error) {
 		_, size, err := s.Kind()
 		if err != nil || size == 0 && s.byteval == 0 {
-			val.Set(reflect.Zero(typ)) // set to nil
+			// rearm s.Kind. This is important because the input
+			// position must advance to the next value even though
+			// we don't read anything.
+			s.kind = -1
+			// set the pointer to nil.
+			val.Set(reflect.Zero(typ))
 			return err
 		}
 		newval := val
-- 
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