[Bitcoin-development] IMPORTANT: if you are running latest git HEAD

Gavin Andresen gavinandresen at gmail.com
Sun Dec 25 16:05:42 UTC 2011

Reposted from the forums:

makomk reported a remote vulnerability that I pulled into the master
bitcoin/bitcoin tree on December 20. If you are running git-HEAD code
on the production network you should pull the latest code to get the
bug fixed.

This affects only anybody who has pulled and compiled their own
bitcoind/bitcoin-qt from the source tree in the last 5 days.

Gory details:

I made a mistake.  I refactored the ConnectInputs() function into two
pieces (FetchInputs() and ConnectInputs()), and should have duplicated
a check in ConnectInputs for an out-of-range
previous-transaction-output in the FetchInputs() method.  The result
was a new method I wrote to help prevent a possible OP_EVAL-related
denial-of-service attack (AreInputsStandard()) could crash with an
out-of-bounds memory access if given an invalid transaction.

The bug-fix puts a check in FetchInputs and an assertion in
AreInputsStandard. This does not affect the back-ported "mining only"
code I wrote that some miners and pools have started using.

The good news is this was found and reported before binaries with the
vulnerability were released; the bad news is this was not found before
the code was pulled and could have made it into the next release if
makomk had not been testing some unrelated code.

Before releasing 0.6, I would like to have an "intelligent,
bitcoin-specific fuzzing tool" that automatically finds this type of
bug that we can run before every release. If anybody already has one,
please speak up!

Gavin Andresen

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