Skip to content

les: add Skip overflow check to GetBlockHeadersMsg handler #16891

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
karalabe merged 1 commit into from
Jun 5, 2018
Merged

les: add Skip overflow check to GetBlockHeadersMsg handler #16891

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
25 changes: 18 additions & 7 deletions les/handler.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ package les

import (
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"math/big"
Expand Down Expand Up @@ -441,7 +442,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {

// Advance to the next header of the query
switch {
case query.Origin.Hash != (common.Hash{}) && query.Reverse:
case hashMode && query.Reverse:
// Hash based traversal towards the genesis block
for i := 0; i < int(query.Skip)+1; i++ {
if header := pm.blockchain.GetHeader(query.Origin.Hash, number); header != nil {
Expand All @@ -452,16 +453,26 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
break
}
}
case query.Origin.Hash != (common.Hash{}) && !query.Reverse:
case hashMode && !query.Reverse:
// Hash based traversal towards the leaf block
if header := pm.blockchain.GetHeaderByNumber(origin.Number.Uint64() + query.Skip + 1); header != nil {
if pm.blockchain.GetBlockHashesFromHash(header.Hash(), query.Skip+1)[query.Skip] == query.Origin.Hash {
query.Origin.Hash = header.Hash()
var (
current = origin.Number.Uint64()
next = current + query.Skip + 1
)
if next <= current {
infos, _ := json.MarshalIndent(p.Peer.Info(), "", " ")
p.Log().Warn("GetBlockHeaders skip overflow attack", "current", current, "skip", query.Skip, "next", next, "attacker", infos)
unknown = true
} else {
if header := pm.blockchain.GetHeaderByNumber(next); header != nil {
if pm.blockchain.GetBlockHashesFromHash(header.Hash(), query.Skip+1)[query.Skip] == query.Origin.Hash {
query.Origin.Hash = header.Hash()
} else {
unknown = true
}
} else {
unknown = true
}
} else {
unknown = true
}
case query.Reverse:
// Number based traversal towards the genesis block
Expand Down