From 3acec3878133c52f4f3a594baf1dcbd6575244bb Mon Sep 17 00:00:00 2001 From: Suhas Daftuar Date: Fri, 6 Oct 2017 14:11:43 -0400 Subject: [PATCH] Don't process unrequested, low-work blocks A peer could try to waste our resources by sending us unrequested blocks with low work, eg to fill up our disk. Since e2652002b6011f793185d473f87f1730c625593b we no longer request blocks until we know we're on a chain with more than nMinimumChainWork (our anti-DoS threshold), but we would still process unrequested blocks that had more work than our tip. This commit fixes that behavior. Github-Pull: #11458 Rebased-From: ce8cd7a7da9174ab151172fc0ce97b5164637cf3 --- src/validation.cpp | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/validation.cpp b/src/validation.cpp index 76b8401f1..3bff2d822 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -3120,6 +3120,12 @@ static bool AcceptBlock(const std::shared_ptr& pblock, CValidation if (pindex->nTx != 0) return true; // This is a previously-processed block that was pruned if (!fHasMoreWork) return true; // Don't process less-work chains if (fTooFarAhead) return true; // Block height is too high + + // Protect against DoS attacks from low-work chains. + // If our tip is behind, a peer could try to send us + // low-work blocks on a fake chain that we would never + // request; don't process these. + if (pindex->nChainWork < nMinimumChainWork) return true; } if (fNewBlock) *fNewBlock = true;