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Avoid uint16 overflow while encoding signatures. #748

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Avoid uint16 overflow while encoding signatures. #748

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765b531
Avoid uint16 overflow error.
winder Feb 20, 2026
bec3117
Avoid uint16 overflow error.
winder Feb 20, 2026
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9 changes: 6 additions & 3 deletions protocol/signature.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import (
"crypto/ecdsa"
"errors"
"fmt"
"math"
"math/big"
"sort"

Expand Down Expand Up @@ -151,11 +152,13 @@ func EncodeSignatures(signatures []Data) ([]byte, error) {
SortSignaturesBySigner(sortedSignatures)

// Calculate signature length (each signature is 64 bytes: 32 R + 32 S)
//nolint:gosec // disable G115
signatureLength := uint16(len(sortedSignatures) * 64)
signatureLength := len(sortedSignatures) * 64
if signatureLength > math.MaxUint16 {
return nil, fmt.Errorf("too many signatures: %d exceeds max uint16", len(sortedSignatures))
}

// Create result buffer
result := make([]byte, 2+int(signatureLength))
result := make([]byte, 2+signatureLength)

// Write signature length as first 2 bytes (big-endian uint16)
result[0] = byte(signatureLength >> 8)
Expand Down
27 changes: 27 additions & 0 deletions protocol/signature_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@ package protocol

import (
"crypto/ecdsa"
"math/big"
"strings"
"testing"

"github.com/ethereum/go-ethereum/common"
Expand Down Expand Up @@ -302,3 +304,28 @@ func TestLeftPad32_InputTooLong(t *testing.T) {
})
}
}

func TestEncodeSignaturesTooMany(t *testing.T) {
// 1024 signatures -> 1024 * 64 = 65536 > math.MaxUint16 (65535)
const n = 1024
sigs := make([]Data, n)
for i := range n {
var r, s [32]byte
r[31] = 1
s[31] = 2
sigs[i] = Data{
R: r,
S: s,
Signer: common.BigToAddress(big.NewInt(int64(i))),
}
}

_, err := EncodeSignatures(sigs)
if err == nil {
t.Fatalf("expected error for too many signatures, got nil")
}

if !strings.Contains(err.Error(), "too many signatures") {
t.Fatalf("unexpected error: %v", err)
}
}
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