les: fix light fetcher database race #16103
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On mobile, so maybe I missed something, but it looks wrong. You check if header is nil... And then use header.Number in the error message. That'll blow up. |
holiman
requested changes
Feb 17, 2018
les/fetcher.go
Outdated
| @@ -562,6 +562,10 @@ func (f *lightFetcher) checkAnnouncedHeaders(fp *fetcherPeerInfo, headers []*typ | |||
| // we ran out of recently delivered headers but have not reached a node known by this peer yet, continue matching | |||
| td = f.chain.GetTd(header.ParentHash, header.Number.Uint64()-1) | |||
| header = f.chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) | |||
| if header == nil || td == nil { | |||
| log.Error("Missing parent of validated header", "hash", header.ParentHash, "number", header.Number.Uint64()-1) | |||
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This will cause error if header is indeed nil
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Right, this one was a really stupid mistake.
les/fetcher.go
Outdated
| @@ -46,7 +46,7 @@ type lightFetcher struct { | |||
| peers map[*peer]*fetcherPeerInfo | |||
| lastUpdateStats *updateStatsEntry | |||
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| lock sync.Mutex // qwerqwerqwe | |||
| lock sync.Mutex | |||
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Couldn't you replace qwerqwerqwe with some documentation about specifically what asset this lock protects?
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prestonvanloon
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Apr 2, 2018
* les: fix light fetcher database race * les: lightFetcher comments
mariameda
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Aug 23, 2018
* les: fix light fetcher database race * les: lightFetcher comments
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This PR fixes #16101 by avoiding a potential chain db data race that can cause checkAnnouncedHeaders being called with a nil header. There is also another check for missing parent of validated header (with an error log message) which in theory should not happen but still it would be nice to know about if it happens anyway in some weird corner case.