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Enforce a combined max stack depth of 1000 after every opcode.

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This limit is for the sum of main and alt stacks. Found by bitcoind
negative tests.
This commit is contained in:
Owain G. Ainsworth 2014-03-14 18:35:36 +00:00
parent d6d755e411
commit dec16d7ff2
1 changed files with 12 additions and 0 deletions
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12
script.go
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@ -116,8 +116,16 @@ var (
// StackErrNonPushOnly is returned when ScriptInfo is called with a // StackErrNonPushOnly is returned when ScriptInfo is called with a
// pkScript that peforms operations other that pushing data to the stack. // pkScript that peforms operations other that pushing data to the stack.
StackErrNonPushOnly = errors.New("SigScript is non pushonly") StackErrNonPushOnly = errors.New("SigScript is non pushonly")
// StackErrOverflow is returned when stack and altstack combined depth
// is over the limit.
StackErrOverflow = errors.New("Stacks overflowed")
) )
// maxStackSize is the maximum combined height of stack and alt stack during
// execution.
const maxStackSize = 1000
// ErrUnsupportedAddress is returned when a concrete type that implements // ErrUnsupportedAddress is returned when a concrete type that implements
// a btcutil.Address is not a supported type. // a btcutil.Address is not a supported type.
var ErrUnsupportedAddress = errors.New("unsupported address type") var ErrUnsupportedAddress = errors.New("unsupported address type")
@ -599,6 +607,10 @@ func (m *Script) Step() (done bool, err error) {
return true, err return true, err
} }
if m.dstack.Depth() + m.astack.Depth() > maxStackSize {
return false, StackErrOverflow
}
// prepare for next instruction // prepare for next instruction
m.scriptoff++ m.scriptoff++
if m.scriptoff >= len(m.scripts[m.scriptidx]) { if m.scriptoff >= len(m.scripts[m.scriptidx]) {