[Bitcoin-development] bitcoind minor bug in wallet and possible fix

[Toshi Morita <toshi@peernova.com>]

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I ran bitcoind under valgrind and found a place where it references an
uninitialized variable in some cases:

tm@tm-VirtualBox:~/bitcoind/bitcoin/src$ valgrind ./bitcoind
==2337== Memcheck, a memory error detector
==2337== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==2337== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==2337== Command: ./bitcoind
==2337==
==2337== Conditional jump or move depends on uninitialised value(s)
==2337==    at 0x319176: CWallet::LoadKeyMetadata(CPubKey const&,
CKeyMetadata const&) (wallet.cpp:110)
==2337==    by 0x33645A: ReadKeyValue(CWallet*, CDataStream&, CDataStream&,
CWalletScanState&, std::string&, std::string&) (walletdb.cpp:509)
==2337==    by 0x3374F0: CWalletDB::LoadWallet(CWallet*) (walletdb.cpp:623)
==2337==    by 0x3218FD: CWallet::LoadWallet(bool&) (wallet.cpp:1485)
==2337==    by 0x157F16: AppInit2(boost::thread_group&) (init.cpp:958)
==2337==    by 0x140142: AppInit(int, char**) (bitcoind.cpp:143)
==2337==    by 0x13649E: main (bitcoind.cpp:180)
==2337==

The bug occurs here because nTimeFirstKey is not initialized when the
wallet is instantiated:

wallet.cpp:63
    if (!nTimeFirstKey || nCreationTime < nTimeFirstKey)
        nTimeFirstKey = nCreationTime;


I fixed it in my fork:

diff --git a/src/wallet.h b/src/wallet.h
index 9607415..b78045f 100644
--- a/src/wallet.h
+++ b/src/wallet.h
@@ -163,6 +163,7 @@ public:
         nOrderPosNext = 0;
         nNextResend = 0;
         nLastResend = 0;
+        nTimeFirstKey = 0;
     }

If this fix is ok please pull from my GitHub fork; username on GitHub is
tm314159.

Toshi

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