| <!DOCTYPE html> |
| <html> |
| <head> |
| <script src="../../resources/js-test.js"></script> |
| <script src="../resources/common.js"></script> |
| </head> |
| <body> |
| <p id="description"></p> |
| <div id="console"></div> |
| |
| <script> |
| description("Test importing a SPKI ECDSA key with invalid length byte causing buffer overread"); |
| |
| // This test verifies that importing a malformed SPKI key where the final |
| // length byte has a large value (0xFF) is rejected gracefully. |
| // Without proper bounds checking, this would cause an unsigned underflow |
| // in the (keyData.size() - index) computation. |
| // |
| // Key structure (25 bytes): |
| // - Offset 0: 0x30 (SequenceMark - outer) |
| // - Offset 1: 0x00 (length byte, bytesUsedToEncodedLength returns 1) |
| // - Offset 2: 0x30 (SequenceMark - inner AlgorithmIdentifier) |
| // - Offset 3: 0x00 (length byte, bytesUsedToEncodedLength returns 1) |
| // - Offset 4-12: IdEcPublicKey OID (06 07 2a 86 48 ce 3d 02 01) |
| // - Offset 13-22: Secp256r1 OID (06 08 2a 86 48 ce 3d 03 01 07) |
| // - Offset 23: 0x03 (BIT STRING mark, skipped by +1) |
| // - Offset 24: 0xFF (length byte, bytesUsedToEncodedLength returns 128) |
| // |
| // index computation: |
| // 1. index = 1 |
| // 2. Check: 25 >= 2 (pass) |
| // 3. index = 1 + 1 + 1 = 3 (Read length, inner SEQUENCE) |
| // 4. Check: 25 >= 4 (pass) |
| // 5. index = 3 + 1 = 4 (Read length) |
| // 6. Check: 25 >= 4 + 9 = 13 (pass), verify IdEcPublicKey |
| // 7. index = 4 + 9 = 13 |
| // 8. Check: 25 >= 13 + 10 = 23 (pass), verify Secp256r1 |
| // 9. index = 13 + 10 + 1 = 24 (Read OID + BIT STRING) |
| // 10. Check: 25 >= 24 + 1 = 25 (pass) |
| // 11. bytesUsedToEncodedLength(0xFF) = 128 |
| // index = 24 + 128 + 1 = 153 |
| // 12. keyData.size() - index = 25 - 153 -> unsigned underflow without bounds check |
| |
| var extractable = true; |
| |
| // 25 bytes: valid SPKI header with IdEcPublicKey + Secp256r1 OIDs, then 0xFF length byte |
| var invalidLengthSpkiKey = hexStringToUint8Array("3000300006072a8648ce3d020106082a8648ce3d03010703ff"); |
| |
| // Should reject with DataError, not crash or read beyond buffer |
| shouldReject('crypto.subtle.importKey("spki", invalidLengthSpkiKey, {name: "ECDSA", namedCurve: "P-256"}, extractable, ["verify"])'); |
| |
| </script> |
| |
| </body> |
| </html> |
