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rlp: fix integer overflow in list element size validation 

It is not safe to add anything to s.size.
This commit is contained in:
Felix Lange 2015-04-14 00:54:12 +02:00
parent 56a48101dc
commit 2750ec47b7
2 changed files with 5 additions and 2 deletions
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4
rlp/decode.go
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@ -751,7 +751,7 @@ func (s *Stream) Kind() (kind Kind, size uint64, err error) {
tos = &s.stack[len(s.stack)-1] tos = &s.stack[len(s.stack)-1]
} }
if s.kind < 0 { if s.kind < 0 {
// don't read further if we're at the end of the // Don't read further if we're at the end of the
// innermost list. // innermost list.
if tos != nil && tos.pos == tos.size { if tos != nil && tos.pos == tos.size {
return 0, 0, EOL return 0, 0, EOL
@ -772,7 +772,7 @@ func (s *Stream) Kind() (kind Kind, size uint64, err error) {
} }
} else { } else {
// Inside a list, check that the value doesn't overflow the list. // Inside a list, check that the value doesn't overflow the list.
if tos.pos+s.size > tos.size { if s.size > tos.size-tos.pos {
return 0, 0, ErrElemTooLarge return 0, 0, ErrElemTooLarge
} }
} }

3
rlp/decode_test.go
View File

@ -112,6 +112,9 @@ func TestStreamErrors(t *testing.T) {
{"BFFFFFFFFFFFFFFFFFFF", calls{"Bytes"}, nil, ErrValueTooLarge}, {"BFFFFFFFFFFFFFFFFFFF", calls{"Bytes"}, nil, ErrValueTooLarge},
{"C801", calls{"List"}, nil, ErrValueTooLarge}, {"C801", calls{"List"}, nil, ErrValueTooLarge},
// Test for list element size check overflow.
{"CD04040404FFFFFFFFFFFFFFFFFF0303", calls{"List", "Uint", "Uint", "Uint", "Uint", "List"}, nil, ErrElemTooLarge},
// Test for input limit overflow. Since we are counting the limit // Test for input limit overflow. Since we are counting the limit
// down toward zero in Stream.remaining, reading too far can overflow // down toward zero in Stream.remaining, reading too far can overflow
// remaining to a large value, effectively disabling the limit. // remaining to a large value, effectively disabling the limit.