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Fix Oracle PostPersist #2074

Merged
merged 24 commits into from
Nov 27, 2020
Merged

Fix Oracle PostPersist #2074

merged 24 commits into from
Nov 27, 2020

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shargon
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@shargon shargon commented Nov 19, 2020

When processing an oracle’s response transaction, it is not verified that the transaction is successful which allows a group of oracle’s nodes to sign a transaction that will throw an exception in the PostPersist method, causing a Denial of Service.

Found by @Red4Sec

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@roman-khimov roman-khimov left a comment

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Isn't it solved by

OracleRequest request = NativeContract.Oracle.GetRequest(snapshot, Id);
if (request is null) return false;
check? The only problem could be multiple transactions for the same ID.

src/neo/SmartContract/Native/Oracle/OracleContract.cs Outdated Show resolved Hide resolved
Tommo-L
Tommo-L previously approved these changes Nov 19, 2020
if (oracle != null &&
(!oracleRequests.TryGetValue(oracle.Id, out var hash) || hash != tx.Hash))
{
return false;
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BTW, this can be replaced with generic "Conflicts" mechanism (#1991) that would also allow for proper transaction to have higher priority over fallback.

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Regarding the description of checking if the transaction was sucesfull you removed that part, right?

As it is right now it is only improving the caching mechanism for avoiding duplicate txs?

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Tommo-L commented Nov 25, 2020

UT failed

/// Store oracle responses
/// </summary>
private readonly Dictionary<ulong, UInt256> oracleResponses = new Dictionary<ulong, UInt256>();

public void AddTransaction(Transaction tx)
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@shargon shargon Nov 26, 2020

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Why don't remove CheckTransaction and Change Add to bool TryAdd (thread-safe)?

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Because CheckTransaction is called in Transaction.Verify().

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Tommo-L commented Nov 27, 2020

Merge?

@erikzhang erikzhang merged commit b6ebbbe into neo-project:master Nov 27, 2020
@shargon shargon deleted the fix-oracle branch November 27, 2020 09:31
ShawnYun pushed a commit to ShawnYun/neo that referenced this pull request Jan 8, 2021
cloud8little pushed a commit to cloud8little/neo that referenced this pull request Jan 24, 2021
ixje added a commit to CityOfZion/neo-mamba that referenced this pull request Feb 2, 2021
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5 participants