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Low 28 Bitcoin Committed May 14, 2026 · 11:36 UTC

feat(ethereum): clear signing support for nested array and byte32

Trezor/Trezor firmware

ba620e9a View source ↗

Public commit record

What the developer wrote

Authored by PrisionMike

62/100 · Adequate

feat(ethereum): clear signing support for nested array and byte32

[no changelog]

✓ Specific, descriptive subject✓ Names a concrete action or component✓ Uses a recognizable type or scope! No meaningful explanatory body

The short version

What changed, and why it matters

This commit adds support in Trezor's Ethereum 'clear signing' feature for two new data shapes: nested arrays (arrays inside arrays) and fixed 32-byte values (bytes32). It also renames an internal helper function from `_request_definitions` to `request_definitions`. The changes are framed as a normal feature addition with no changelog entry. There is no direct evidence in the commit that this fixes a security vulnerability, but any change to transaction parsing logic can affect how the device interprets maliciously crafted data.

Recommended action

Treat as a routine feature commit but include it in any review of Ethereum clear-signing robustness. Verify that the new nested-array offset arithmetic cannot be abused to bypass bounds checks, and confirm that bytes32 values are displayed to the user in a way that prevents confusion with addresses or hashes. No immediate security action is indicated by the diff alone.

Security signals we found

Parsing logic change for externally supplied Ethereum transaction/call data

New fixed-size bytes32 parser added with explicit length check

Nested array support added with relative-offset resolution and bounds checks

Out-of-bounds test cases added for nested arrays

No changelog entry despite user-facing parser change

Technical analysis

Evidence from the diff

The patch extends the Ethereum ABI parser used for ERC-7730 clear signing. It adds ABI_BYTES32 to the protobuf enum and wires a new parse_bytes32 parser that returns the first 32 bytes of a 32-byte word. It also enables one level of nested arrays (Array(Array(...))) by handling element.array inside ABIValue.from_field() and adding a recursive _parse_body path in the Array class. Offsets are validated against len(raw_data) and raise OutOfBounds on overflow. The function _request_definitions is renamed to request_definitions and three call sites are updated. Tests cover bytes32 parsing, nested array parsing, and out-of-bounds cases.

Changed components

core/src/apps/ethereum/clear_signing.pycommon/protob/messages-definitions.protocore/src/trezor/enums/EthereumABIType.pycore/src/trezor/enums/__init__.pypython/src/trezorlib/messages.pyrust/trezor-client/src/protos/generated/messages_definitions.rscore/tests/test_apps.ethereum.clear_signing.py

Inspect captured patch +144 / −23

diff --git a/common/protob/messages-definitions.proto b/common/protob/messages-definitions.proto
index f310c0c7..09c501f2 100644
--- a/common/protob/messages-definitions.proto
+++ b/common/protob/messages-definitions.proto
@@ -92,6 +92,7 @@ enum EthereumABIType {
     ABI_UINT16 = 14;
     ABI_UINT8 = 15;
     ABI_BOOL = 16;
+    ABI_BYTES32 = 17;
     ABI_BYTES = 20;
     ABI_STRING = 21;
 }
diff --git a/core/src/apps/ethereum/clear_signing.py b/core/src/apps/ethereum/clear_signing.py
index 456bb5f2..02e08549 100644
--- a/core/src/apps/ethereum/clear_signing.py
+++ b/core/src/apps/ethereum/clear_signing.py
@@ -138,6 +138,12 @@ parse_uint16 = _make_uint_parser(16)
 parse_uint8 = _make_uint_parser(8)
 
 
+def parse_bytes32(raw_data: memoryview) -> Value:
+    if len(raw_data) < 32:
+        raise OutOfBounds
+    return bytes(raw_data[:32])
+
+
 def parse_bool(raw_data: memoryview) -> Value:
     if len(raw_data) < 32:
         raise OutOfBounds
@@ -214,6 +220,8 @@ def _get_parser(t: int, is_dynamic: bool) -> Parser:
         return parse_uint8
     elif t == T.ABI_BOOL:
         return parse_bool
+    elif t == T.ABI_BYTES32:
+        return parse_bytes32
     raise InvalidFormatDefinition
 
 
@@ -332,7 +340,7 @@ class TokenAmountFormatter(FieldFormatter):
         token = defs.get_token(token_address)
         if token is UNKNOWN_TOKEN:
             if msg.supports_definition_request:
-                received_definitions, _ = await _request_definitions(
+                received_definitions, _ = await request_definitions(
                     msg.chain_id, token_address, func_sig=None
                 )
                 if received_definitions is not None:
@@ -436,7 +444,18 @@ class ABIValue:
                         is_dynamic=False,  # Tuples inside Arrays are always parsed as static!
                     )
                 )
-            raise InvalidFormatDefinition  # Array of arrays not supported
+            elif element.array is not None:
+                inner = element.array
+                if inner.atomic is not None:
+                    return Array(
+                        Array(Atomic(_get_parser(inner.atomic, is_dynamic=False)))
+                    )
+                elif inner.dynamic is not None:
+                    return Array(
+                        Array(Dynamic(_get_parser(inner.dynamic, is_dynamic=True)))
+                    )
+                raise InvalidFormatDefinition  # deeper nesting not supported
+            raise InvalidFormatDefinition
         raise InvalidFormatDefinition
 
 
@@ -538,33 +557,39 @@ class Array(ABIValue):
         if offset + 32 > len(raw_data):
             raise OutOfBounds
         array_pointer = int.from_bytes(raw_data[offset : offset + 32], "big")
-        if array_pointer + 32 > len(raw_data):
+        return self._parse_body(raw_data, array_pointer), 32
+
+    def _parse_body(self, raw_data: memoryview, array_start: int) -> ListValue:
+        if array_start + 32 > len(raw_data):
             raise OutOfBounds
-        array_length = int.from_bytes(
-            raw_data[array_pointer : array_pointer + 32], "big"
-        )
-        array_heads_end = array_pointer + 32 + (array_length * 32)
+        array_length = int.from_bytes(raw_data[array_start : array_start + 32], "big")
+        array_heads_end = array_start + 32 + (array_length * 32)
         if array_heads_end > len(raw_data):
             raise OutOfBounds
 
         value = []
 
         for i in range(array_length):
-            p = array_pointer + 32 + (i * 32)
+            p = array_start + 32 + (i * 32)
             if p + 32 > len(raw_data):
                 raise OutOfBounds
             if isinstance(self.element_definition, Atomic):
                 # atomic types are encoded in place
                 data, _ = self.element_definition.parse(raw_data, p)
+            elif isinstance(self.element_definition, Array):
+                # inner arrays: element head is a relative offset to the inner array body
+                element_pointer = int.from_bytes(raw_data[p : p + 32], "big")
+                inner_array_start = array_start + 32 + element_pointer
+                data = self.element_definition._parse_body(raw_data, inner_array_start)
             else:
                 element_pointer = int.from_bytes(raw_data[p : p + 32], "big")
-                element_absolute_pointer = array_pointer + 32 + element_pointer
+                element_absolute_pointer = array_start + 32 + element_pointer
                 data, _ = self.element_definition.parse(
                     raw_data, element_absolute_pointer
                 )
             value.append(data)
 
-        return value, 32  # arrays just consume the pointer
+        return value
 
 
 # https://eips.ethereum.org/EIPS/eip-7730#evm-transaction-container
@@ -775,7 +800,7 @@ class DisplayFormat:
         )
 
 
-async def _request_definitions(
+async def request_definitions(
     chain_id: int, token_address: bytes, func_sig: bytes | None
 ) -> tuple[Definitions | None, DisplayFormat | None]:
     from trezor.messages import EthereumDefinitionAck, EthereumDefinitionRequest
@@ -844,7 +869,7 @@ async def try_confirm(
         if display_format is None:
             # ... finally request the display format via another call!
             if msg.supports_definition_request:
-                _, f = await _request_definitions(msg.chain_id, address_bytes, func_sig)
+                _, f = await request_definitions(msg.chain_id, address_bytes, func_sig)
                 if f:
                     if f.func_sig == func_sig and f.matches_context(
                         msg.chain_id, address_bytes
diff --git a/core/src/trezor/enums/EthereumABIType.py b/core/src/trezor/enums/EthereumABIType.py
index b319b2f5..4f995cb6 100644
--- a/core/src/trezor/enums/EthereumABIType.py
+++ b/core/src/trezor/enums/EthereumABIType.py
@@ -19,5 +19,6 @@ ABI_UINT24 = 13
 ABI_UINT16 = 14
 ABI_UINT8 = 15
 ABI_BOOL = 16
+ABI_BYTES32 = 17
 ABI_BYTES = 20
 ABI_STRING = 21
diff --git a/core/src/trezor/enums/__init__.py b/core/src/trezor/enums/__init__.py
index 590741a8..b9b0880b 100644
--- a/core/src/trezor/enums/__init__.py
+++ b/core/src/trezor/enums/__init__.py
@@ -309,6 +309,7 @@ if TYPE_CHECKING:
         ABI_UINT16 = 14
         ABI_UINT8 = 15
         ABI_BOOL = 16
+        ABI_BYTES32 = 17
         ABI_BYTES = 20
         ABI_STRING = 21
 
diff --git a/core/tests/test_apps.ethereum.clear_signing.py b/core/tests/test_apps.ethereum.clear_signing.py
index 44a667a0..d7de03f3 100644
--- a/core/tests/test_apps.ethereum.clear_signing.py
+++ b/core/tests/test_apps.ethereum.clear_signing.py
@@ -16,6 +16,7 @@ if not utils.BITCOIN_ONLY:
         ValueOverflow,
         parse_address,
         parse_bool,
+        parse_bytes32,
         parse_string,
         parse_uint24,
         parse_uint160,
@@ -224,7 +225,9 @@ class TestEthereumClearSigning(unittest.TestCase):
 
         array_length = len([addr1, addr2])
 
-        array_pointer = len(FIVE_RANDOM_BYTES) + 32  # payload start + pointer size
+        array_pointer = (
+            len(FIVE_RANDOM_BYTES) + 32
+        )  # absolute position of body in raw_data
         payload = (
             to_bytes(array_pointer)
             + to_bytes(array_length)
@@ -310,6 +313,88 @@ class TestEthereumClearSigning(unittest.TestCase):
         self.assertEqual(parsed, [(addr1, text1), (addr2, text2)])
         self.assertEqual(consumed, 32)
 
+    def test_bytes32_parsing(self):
+        atomic_bytes32 = Atomic(parse_bytes32)
+
+        b32 = bytes(range(32))
+        data = memoryview(FIVE_RANDOM_BYTES + b32 + SEVEN_RANDOM_BYTES)
+        parsed, consumed = atomic_bytes32.parse(data, len(FIVE_RANDOM_BYTES))
+        self.assertEqual(parsed, b32)
+        self.assertEqual(consumed, 32)
+
+        with self.assertRaises(OutOfBounds):
+            atomic_bytes32.parse(memoryview(b"\x00" * 20), 0)
+
+    def test_array_of_arrays_of_bytes32(self):
+        # bytes32[][] = [[b0, b1], [b2]]
+        nested_array_parser = Array(Array(Atomic(parse_bytes32)))
+
+        b0 = bytes(range(0, 32))
+        b1 = bytes(range(32, 64))
+        b2 = bytes(range(64, 96))
+
+        # ABI layout (offsets are absolute positions within raw_data):
+        #   [7]:   pointer slot → outer body at 7+32 = 39
+        #   [39]:  outer length = 2
+        #   [71]:  rel. offset to inner[0] from heads base (=71): 135-71 = 64
+        #   [103]: rel. offset to inner[1] from heads base (=71): 231-71 = 160
+        #   [135]: inner[0] length = 2
+        #   [167]: inner[0][0] = b0
+        #   [199]: inner[0][1] = b1
+        #   [231]: inner[1] length = 1
+        #   [263]: inner[1][0] = b2
+        payload = (
+            to_bytes(
+                len(SEVEN_RANDOM_BYTES) + 32
+            )  # pointer: absolute raw_data pos of outer body
+            + to_bytes(2)  # outer length
+            + to_bytes(64)  # rel. offset → inner[0]
+            + to_bytes(160)  # rel. offset → inner[1]
+            + to_bytes(2)  # inner[0] length
+            + b0
+            + b1
+            + to_bytes(1)  # inner[1] length
+            + b2
+        )
+        data = memoryview(SEVEN_RANDOM_BYTES + payload + FIVE_RANDOM_BYTES)
+
+        parsed, consumed = nested_array_parser.parse(data, len(SEVEN_RANDOM_BYTES))
+        self.assertEqual(parsed, [[b0, b1], [b2]])
+        self.assertEqual(consumed, 32)
+
+    def test_array_of_arrays_out_of_bounds(self):
+        nested_array_parser = Array(Array(Atomic(parse_bytes32)))
+
+        # outer array pointer points beyond the data
+        payload = to_bytes(9999)
+        with self.assertRaises(OutOfBounds):
+            nested_array_parser.parse(memoryview(payload), 0)
+
+        # inner array length overruns the data — test both sides of the border
+
+        # border valid: inner[0] length = 0 → empty inner array, parses as [[]]
+        # pointer = len(SEVEN_RANDOM_BYTES) + 32 = absolute raw_data pos of outer body
+        payload_ok = (
+            to_bytes(len(SEVEN_RANDOM_BYTES) + 32)  # pointer to outer body
+            + to_bytes(1)  # outer length = 1
+            + to_bytes(32)  # rel. offset to inner[0] from heads base
+            + to_bytes(0)  # inner[0] length = 0 → empty
+        )
+        data = memoryview(SEVEN_RANDOM_BYTES + payload_ok + FIVE_RANDOM_BYTES)
+        parsed, consumed = nested_array_parser.parse(data, len(SEVEN_RANDOM_BYTES))
+        self.assertEqual(parsed, [[]])
+        self.assertEqual(consumed, 32)
+
+        # border invalid: inner[0] length = 1 but no element data follows
+        payload_fail = (
+            to_bytes(32)  # pointer to outer body (no prefix, absolute pos = 32)
+            + to_bytes(1)  # outer length = 1
+            + to_bytes(32)  # rel. offset to inner[0] from heads base
+            + to_bytes(1)  # inner[0] length = 1 — one element claimed but no data
+        )
+        with self.assertRaises(OutOfBounds):
+            nested_array_parser.parse(memoryview(payload_fail), 0)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/python/src/trezorlib/messages.py b/python/src/trezorlib/messages.py
index 7b8a1ef7..a56eeae8 100644
--- a/python/src/trezorlib/messages.py
+++ b/python/src/trezorlib/messages.py
@@ -350,6 +350,7 @@ class EthereumABIType(IntEnum):
     ABI_UINT16 = 14
     ABI_UINT8 = 15
     ABI_BOOL = 16
+    ABI_BYTES32 = 17
     ABI_BYTES = 20
     ABI_STRING = 21
 
diff --git a/rust/trezor-client/src/protos/generated/messages_definitions.rs b/rust/trezor-client/src/protos/generated/messages_definitions.rs
index 5478f856..ef46255a 100644
--- a/rust/trezor-client/src/protos/generated/messages_definitions.rs
+++ b/rust/trezor-client/src/protos/generated/messages_definitions.rs
@@ -2426,6 +2426,8 @@ pub enum EthereumABIType {
     ABI_UINT8 = 15,
     // @@protoc_insertion_point(enum_value:hw.trezor.messages.definitions.EthereumABIType.ABI_BOOL)
     ABI_BOOL = 16,
+    // @@protoc_insertion_point(enum_value:hw.trezor.messages.definitions.EthereumABIType.ABI_BYTES32)
+    ABI_BYTES32 = 17,
     // @@protoc_insertion_point(enum_value:hw.trezor.messages.definitions.EthereumABIType.ABI_BYTES)
     ABI_BYTES = 20,
     // @@protoc_insertion_point(enum_value:hw.trezor.messages.definitions.EthereumABIType.ABI_STRING)
@@ -2458,6 +2460,7 @@ impl ::protobuf::Enum for EthereumABIType {
             14 => ::std::option::Option::Some(EthereumABIType::ABI_UINT16),
             15 => ::std::option::Option::Some(EthereumABIType::ABI_UINT8),
             16 => ::std::option::Option::Some(EthereumABIType::ABI_BOOL),
+            17 => ::std::option::Option::Some(EthereumABIType::ABI_BYTES32),
             20 => ::std::option::Option::Some(EthereumABIType::ABI_BYTES),
             21 => ::std::option::Option::Some(EthereumABIType::ABI_STRING),
             _ => ::std::option::Option::None
@@ -2483,6 +2486,7 @@ impl ::protobuf::Enum for EthereumABIType {
             "ABI_UINT16" => ::std::option::Option::Some(EthereumABIType::ABI_UINT16),
             "ABI_UINT8" => ::std::option::Option::Some(EthereumABIType::ABI_UINT8),
             "ABI_BOOL" => ::std::option::Option::Some(EthereumABIType::ABI_BOOL),
+            "ABI_BYTES32" => ::std::option::Option::Some(EthereumABIType::ABI_BYTES32),
             "ABI_BYTES" => ::std::option::Option::Some(EthereumABIType::ABI_BYTES),
             "ABI_STRING" => ::std::option::Option::Some(EthereumABIType::ABI_STRING),
             _ => ::std::option::Option::None
@@ -2507,6 +2511,7 @@ impl ::protobuf::Enum for EthereumABIType {
         EthereumABIType::ABI_UINT16,
         EthereumABIType::ABI_UINT8,
         EthereumABIType::ABI_BOOL,
+        EthereumABIType::ABI_BYTES32,
         EthereumABIType::ABI_BYTES,
         EthereumABIType::ABI_STRING,
     ];
@@ -2537,8 +2542,9 @@ impl ::protobuf::EnumFull for EthereumABIType {
             EthereumABIType::ABI_UINT16 => 14,
             EthereumABIType::ABI_UINT8 => 15,
             EthereumABIType::ABI_BOOL => 16,
-            EthereumABIType::ABI_BYTES => 17,
-            EthereumABIType::ABI_STRING => 18,
+            EthereumABIType::ABI_BYTES32 => 17,
+            EthereumABIType::ABI_BYTES => 18,
+            EthereumABIType::ABI_STRING => 19,
         };
         Self::enum_descriptor().value_by_index(index)
     }
@@ -2741,7 +2747,7 @@ static file_descriptor_proto_data: &'static [u8] = b"\
     \x20\x03(\x0b28.hw.trezor.messages.definitions.EthereumERC7730FieldInfoR\
     \x10fieldDefinitions*i\n\x0eDefinitionType\x12\x14\n\x10ETHEREUM_NETWORK\
     \x10\0\x12\x12\n\x0eETHEREUM_TOKEN\x10\x01\x12\x10\n\x0cSOLANA_TOKEN\x10\
-    \x02\x12\x1b\n\x17ETHEREUM_DISPLAY_FORMAT\x10\x03*\xc4\x02\n\x0fEthereum\
+    \x02\x12\x1b\n\x17ETHEREUM_DISPLAY_FORMAT\x10\x03*\xd5\x02\n\x0fEthereum\
     ABIType\x12\x0f\n\x0bABI_ADDRESS\x10\0\x12\x0f\n\x0bABI_UINT256\x10\x01\
     \x12\x0f\n\x0bABI_UINT248\x10\x02\x12\x0f\n\x0bABI_UINT160\x10\x03\x12\
     \x0f\n\x0bABI_UINT128\x10\x04\x12\x0f\n\x0bABI_UINT120\x10\x05\x12\x0f\n\
@@ -2749,13 +2755,14 @@ static file_descriptor_proto_data: &'static [u8] = b"\
     T72\x10\x08\x12\x0e\n\nABI_UINT64\x10\t\x12\x0e\n\nABI_UINT48\x10\n\x12\
     \x0e\n\nABI_UINT40\x10\x0b\x12\x0e\n\nABI_UINT32\x10\x0c\x12\x0e\n\nABI_\
     UINT24\x10\r\x12\x0e\n\nABI_UINT16\x10\x0e\x12\r\n\tABI_UINT8\x10\x0f\
-    \x12\x0c\n\x08ABI_BOOL\x10\x10\x12\r\n\tABI_BYTES\x10\x14\x12\x0e\n\nABI\
-    _STRING\x10\x15*\x85\x01\n!EthereumERC7730FieldFormatterType\x12\x1a\n\
-    \x16FORMATTER_ADDRESS_NAME\x10\0\x12\x14\n\x10FORMATTER_AMOUNT\x10\x01\
-    \x12\x1a\n\x16FORMATTER_TOKEN_AMOUNT\x10\x02\x12\x12\n\x0eFORMATTER_UNIT\
-    \x10\x03*;\n\x1cEthereumERC7730ContainerPath\x12\x08\n\x04FROM\x10\x01\
-    \x12\t\n\x05VALUE\x10\x02\x12\x06\n\x02TO\x10\x03B?\n#com.satoshilabs.tr\
-    ezor.lib.protobufB\x18TrezorMessageDefinitions\
+    \x12\x0c\n\x08ABI_BOOL\x10\x10\x12\x0f\n\x0bABI_BYTES32\x10\x11\x12\r\n\
+    \tABI_BYTES\x10\x14\x12\x0e\n\nABI_STRING\x10\x15*\x85\x01\n!EthereumERC\
+    7730FieldFormatterType\x12\x1a\n\x16FORMATTER_ADDRESS_NAME\x10\0\x12\x14\
+    \n\x10FORMATTER_AMOUNT\x10\x01\x12\x1a\n\x16FORMATTER_TOKEN_AMOUNT\x10\
+    \x02\x12\x12\n\x0eFORMATTER_UNIT\x10\x03*;\n\x1cEthereumERC7730Container\
+    Path\x12\x08\n\x04FROM\x10\x01\x12\t\n\x05VALUE\x10\x02\x12\x06\n\x02TO\
+    \x10\x03B?\n#com.satoshilabs.trezor.lib.protobufB\x18TrezorMessageDefini\
+    tions\
 ";
 
 /// `FileDescriptorProto` object which was a source for this generated file

Risk score

Why this scored 28/100

Our methodology →

Potential impact 5/30

Exploitability 5/25

Stealth signal 5/15

Affected reach 5/15

Confidence 5/10

Evidence quality 3/5

Human-validated context

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No validated notes yet.

The AI analysis stands alone for now. Submit a note if you can add evidence or important context.

What the developer wrote

What changed, and why it matters

Security signals we found

Evidence from the diff

Changed components

Why this scored 28/100

Community notes

Related watches

fix(python/trezorlib): enable entropy check on T1 by default

chore(core): remove scons related files

refactor(core): assorted micropython-1.28.0 fixes