Don't attempt to resize vector to negative size. #2705

pull robbak wants to merge 1 commits into bitcoin:master from robbak:crash_zero_size_peers.dat changing 1 files +2 −0

robbak commented at 2:22 AM on May 29, 2013: contributor

When my system crashes, the peers.dat file often ends up zero-sized. When this happens, vector vchData.resize(dataSize) is handed a negative dataSize. It takes it as an unsigned int and attempts to resize it to 18 hexillion bytes, crashing with a std::bad_alloc, which is presented as "bitcoin in Runaway exception"

This pull simply adds a 'if ( dataSize < 0 ) dataSize = 0;' check before running resize(). Another option would be to make the resize() call itself conditional on dataSize being positive.
Don't attempt to resize vector to negative size. 98ab2b5a26
BitcoinPullTester commented at 3:19 AM on May 29, 2013: none

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sipa commented at 5:49 PM on May 29, 2013: member

This seems harmless.

in src/db.cpp:None in 98ab2b5a26

 540 | @@ -541,6 +541,8 @@ bool CAddrDB::Read(CAddrMan& addr)
 541 |      // use file size to size memory buffer
 542 |      int fileSize = GetFilesize(filein);
 543 |      int dataSize = fileSize - sizeof(uint256);
 544 | +    //Don't try to resize to a negative number if file is small
 545 | +    if ( dataSize < 0 ) dataSize = 0;

laanwj commented at 12:16 PM on May 30, 2013:

May be handle the problem immediately, ie do an return error("...") here (though I suppose when the file is too short, it will fail later anyway when doing filein >> hashIn, so it may not matter apart from clarity)

jgarzik referenced this in commit 87ec1929cf on May 30, 2013
jgarzik merged this on May 30, 2013
jgarzik closed this on May 30, 2013
DrahtBot locked this on Sep 8, 2021

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