lint and update comment

tests/functional/builtins/codegen/test_abi_decode.py

@@ -470,7 +470,8 @@ def test_abi_decode_length_mismatch(get_contract, assert_compile_failed, bad_cod
 
 
 def test_abi_decode_overflow(w3, tx_failed, get_contract):
-    # test based on GHSA-9p8r-4xp4-gw5w: https://github.com/vyperlang/vyper/security/advisories/GHSA-9p8r-4xp4-gw5w#advisory-comment-91841
+    # test based on GHSA-9p8r-4xp4-gw5w:
+    # https://github.com/vyperlang/vyper/security/advisories/GHSA-9p8r-4xp4-gw5w#advisory-comment-91841
     # note: doesn't even reach the assert but reverts internally on the clamp in getelemptr
     code = """
 @external
@@ -485,7 +486,10 @@ def f(x: Bytes[32 * 3]):
     assert decoded_y1 != decoded_y2
     """
     c = get_contract(code)
-    data = "d45754f800000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000060ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa0"
+    data = "d45754f8"
+    data += "20".zfill(64)
+    data += "60".zfill(64)
+    data += "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa0"
     with tx_failed():
         w3.eth.send_transaction({"to": c.address, "data": data})
 
@@ -510,4 +514,4 @@ def f(x: Bytes[32 * 5]):
     data += "40".zfill(64)  # inner array head
     data += "3".zfill(64) * 4  # inner array payload - length: 3 | idx0: 3 | idx1: 3 | idx2: 3
     with tx_failed():
-        w3.eth.send_transaction({"to": c.address, "data": data})
+        w3.eth.send_transaction({"to": c.address, "data": data})

vyper/codegen/core.py

@@ -468,15 +468,11 @@ def _getelemptr_abi_helper(parent, member_t, ofst, clamp_=True):
             with abi_ofst.cache_when_complex("abi_ofst") as (b1, abi_ofst):
                 bound = parent_abi_t.size_bound()
                 end = ["add", abi_ofst, member_abi_t.size_bound()]
-                # head + member_size must be 'le' upper_bound of the parent buffer
+                # head + member_size must be 'le' than the upper bound of parent buffer
                 end_clamped = clamp("le", end, bound)
-                # head + member_size must be 'gt' lower_bound of the parent buffer (no overflow)
+                # head + member_size must be 'gt' than the head (ie no overflow due to 'add')
                 end_clamped = ["assert", ["gt", end_clamped, abi_ofst]]
-                ofst_ir = [
-                    "seq",
-                    end_clamped,
-                    add_ofst(parent, abi_ofst)
-                ]
+                ofst_ir = ["seq", end_clamped, add_ofst(parent, abi_ofst)]
                 ofst_ir = b1.resolve(ofst_ir)
 
     return IRnode.from_list(