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fix: potential index out of range panic #8

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merged 1 commit into from
Mar 1, 2022
Merged

fix: potential index out of range panic #8

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18 changes: 14 additions & 4 deletions protocol/authenticator.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,10 @@ import (
"github.com/go-webauthn/webauthn/protocol/webauthncbor"
)

var minAuthDataLength = 37
var (
minAuthDataLength = 37
minAttestedAuthLength = 55
)

// Authenticators respond to Relying Party requests by returning an object derived from the
// AuthenticatorResponse interface. See §5.2. Authenticator Responses
Expand Down Expand Up @@ -159,8 +162,11 @@ func (a *AuthenticatorData) Unmarshal(rawAuthData []byte) error {
remaining := len(rawAuthData) - minAuthDataLength

if a.Flags.HasAttestedCredentialData() {
if len(rawAuthData) > minAuthDataLength {
a.unmarshalAttestedData(rawAuthData)
if len(rawAuthData) > minAttestedAuthLength {
validError := a.unmarshalAttestedData(rawAuthData)
if validError != nil {
return validError
}
attDataLen := len(a.AttData.AAGUID) + 2 + len(a.AttData.CredentialID) + len(a.AttData.CredentialPublicKey)
remaining = remaining - attDataLen
} else {
Expand Down Expand Up @@ -189,11 +195,15 @@ func (a *AuthenticatorData) Unmarshal(rawAuthData []byte) error {
}

// If Attestation Data is present, unmarshall that into the appropriate public key structure
func (a *AuthenticatorData) unmarshalAttestedData(rawAuthData []byte) {
func (a *AuthenticatorData) unmarshalAttestedData(rawAuthData []byte) error {
a.AttData.AAGUID = rawAuthData[37:53]
idLength := binary.BigEndian.Uint16(rawAuthData[53:55])
if len(rawAuthData) < int(55+idLength) {
return ErrBadRequest.WithDetails("Authenticator attestation data length too short")
}
a.AttData.CredentialID = rawAuthData[55 : 55+idLength]
a.AttData.CredentialPublicKey = unmarshalCredentialPublicKey(rawAuthData[55+idLength:])
return nil
}

// Unmarshall the credential's Public Key into CBOR encoding
Expand Down
11 changes: 7 additions & 4 deletions protocol/authenticator_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -184,9 +184,10 @@ func TestAuthenticatorData_unmarshalAttestedData(t *testing.T) {
rawAuthData []byte
}
tests := []struct {
name string
fields fields
args args
name string
fields fields
args args
wantErr bool
}{
// TODO: Add test cases.
}
Expand All @@ -199,7 +200,9 @@ func TestAuthenticatorData_unmarshalAttestedData(t *testing.T) {
AttData: tt.fields.AttData,
ExtData: tt.fields.ExtData,
}
a.unmarshalAttestedData(tt.args.rawAuthData)
if err := a.unmarshalAttestedData(tt.args.rawAuthData); (err != nil) != tt.wantErr {
t.Errorf("AuthenticatorData.unmarshalAttestedData() error = %v, wantErr %v", err, tt.wantErr)
}
})
}
}
Expand Down