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eth/protocols/eth: Fix overflows in GetBlockHeaders #31522

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Merged
merged 3 commits into from
Apr 3, 2025
Merged

eth/protocols/eth: Fix overflows in GetBlockHeaders #31522

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eth/protocols/eth: fix overflows in GetBlockHeader
antonis19 Mar 28, 2025
abb7c94
update comments
antonis19 Mar 28, 2025
6d9cf62
remove warning logs
antonis19 Mar 28, 2025
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28 changes: 28 additions & 0 deletions eth/protocols/eth/handler_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -297,6 +297,34 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
backend.chain.GetBlockByNumber(0).Hash(),
},
},
// Check a corner case where skipping causes overflow with reverse=false
{
&GetBlockHeadersRequest{Origin: HashOrNumber{Number: 1}, Amount: 2, Reverse: false, Skip: math.MaxUint64 - 1},
[]common.Hash{
backend.chain.GetBlockByNumber(1).Hash(),
},
},
// Check a corner case where skipping causes overflow with reverse=true
{
&GetBlockHeadersRequest{Origin: HashOrNumber{Number: 1}, Amount: 2, Reverse: true, Skip: math.MaxUint64 - 1},
[]common.Hash{
backend.chain.GetBlockByNumber(1).Hash(),
},
},
// Check another corner case where skipping causes overflow with reverse=false
{
&GetBlockHeadersRequest{Origin: HashOrNumber{Number: 1}, Amount: 2, Reverse: false, Skip: math.MaxUint64},
[]common.Hash{
backend.chain.GetBlockByNumber(1).Hash(),
},
},
// Check another corner case where skipping causes overflow with reverse=true
{
&GetBlockHeadersRequest{Origin: HashOrNumber{Number: 1}, Amount: 2, Reverse: true, Skip: math.MaxUint64},
[]common.Hash{
backend.chain.GetBlockByNumber(1).Hash(),
},
},
// Check a corner case where skipping overflow loops back into the chain start
{
&GetBlockHeadersRequest{Origin: HashOrNumber{Hash: backend.chain.GetBlockByNumber(3).Hash()}, Amount: 2, Reverse: false, Skip: math.MaxUint64 - 1},
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17 changes: 12 additions & 5 deletions eth/protocols/eth/handlers.go
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Original file line number Diff line number Diff line change
Expand Up @@ -128,15 +128,22 @@ func serviceNonContiguousBlockHeaderQuery(chain *core.BlockChain, query *GetBloc
}
case query.Reverse:
// Number based traversal towards the genesis block
if query.Origin.Number >= query.Skip+1 {
query.Origin.Number -= query.Skip + 1
} else {
current := query.Origin.Number
ancestor := current - (query.Skip + 1)
if ancestor >= current { // check for underflow
unknown = true
} else {
query.Origin.Number = ancestor
}

case !query.Reverse:
// Number based traversal towards the leaf block
query.Origin.Number += query.Skip + 1
current := query.Origin.Number
next := current + query.Skip + 1
if next <= current { // check for overflow
unknown = true
} else {
query.Origin.Number = next
}
}
}
return headers
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