Merge pull request #121 from fluffypony/master

Fix tree_hash, patch for bad block 202612
This commit is contained in:
Riccardo Spagni 2014-09-06 21:57:37 +02:00
commit 3c2b74215b
4 changed files with 96 additions and 10 deletions

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@ -35,7 +35,43 @@
#include "hash-ops.h"
/// Quick check if this is power of two (use on unsigned types; in this case for size_t only)
bool ispowerof2_size_t(size_t x) {
return x && !(x & (x - 1));
}
/***
* Round to power of two, for count>=3 and for count being not too large (as reasonable for tree hash calculations)
*/
size_t tree_hash_cnt(size_t count) {
assert( count >= 3); // cases for 0,1,2 are handled elsewhere
// Round down the count size: fun(2**n)= 2**(n-1) to round down to power of two
size_t tmp = count - 1;
size_t jj = 1;
for (jj=1 ; tmp != 0 ; ++jj) {
tmp /= 2; // dividing by 2 until to get how many powers of 2 fits size_to tmp
}
size_t cnt = 1 << (jj-2); // cnt is the count, but rounded down to power of two
// printf("count=%zu cnt=%zu jj=%zu tmp=%zu \n" , count,cnt,jj,tmp);
assert( cnt > 0 ); assert( cnt >= count/2 ); assert( cnt <= count );
assert( ispowerof2_size_t( cnt ));
return cnt;
}
void tree_hash(const char (*hashes)[HASH_SIZE], size_t count, char *root_hash) {
// The blockchain block at height 202612 http://monerochain.info/block/bbd604d2ba11ba27935e006ed39c9bfdd99b76bf4a50654bc1e1e61217962698
// contained 514 transactions, that triggered bad calculation of variable "cnt" in the original version of this function
// as from CryptoNote code.
//
// This bug applies to all CN altcoins.
//
// Mathematical bug here was first published on 14:45:34 (GMT+2) 2014-09-04 by Rafal Freeman <rfree>
// https://github.com/rfree2monero/bitmonero/commit/b417abfb7a297d09f1bbb6de29030f8de9952ac8
// and soon also applied to CryptoNote (15:10 GMT+2), and BoolBerry used not fully correct work around:
// the work around of sizeof(size_t)*8 or <<3 as used before in 2 coins and in BBL later was blocking
// exploitation on normal platforms, how ever we strongly recommend the following fix because it removes
// mistake in mathematical formula.
assert(count > 0);
if (count == 1) {
memcpy(root_hash, hashes, HASH_SIZE);
@ -43,24 +79,30 @@ void tree_hash(const char (*hashes)[HASH_SIZE], size_t count, char *root_hash) {
cn_fast_hash(hashes, 2 * HASH_SIZE, root_hash);
} else {
size_t i, j;
size_t cnt = count - 1;
size_t cnt = tree_hash_cnt( count );
size_t max_size_t = (size_t) -1; // max allowed value of size_t
assert( cnt < max_size_t/2 ); // reasonable size to avoid any overflows. /2 is extra; Anyway should be limited much stronger by logical code
// as we have sane limits on transactions counts in blockchain rules
char (*ints)[HASH_SIZE];
for (i = 1; i < sizeof(size_t); i <<= 1) {
cnt |= cnt >> i;
}
cnt &= ~(cnt >> 1);
ints = alloca(cnt * HASH_SIZE);
size_t ints_size = cnt * HASH_SIZE;
ints = alloca(ints_size); memset( ints , 0 , ints_size); // allocate, and zero out as extra protection for using uninitialized mem
memcpy(ints, hashes, (2 * cnt - count) * HASH_SIZE);
for (i = 2 * cnt - count, j = 2 * cnt - count; j < cnt; i += 2, ++j) {
cn_fast_hash(hashes[i], 64, ints[j]);
}
assert(i == count);
while (cnt > 2) {
cnt >>= 1;
for (i = 0, j = 0; j < cnt; i += 2, ++j) {
cn_fast_hash(ints[i], 64, ints[j]);
}
}
cn_fast_hash(ints[0], 64, root_hash);
}
}

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@ -88,7 +88,28 @@ bool blockchain_storage::init(const std::string& config_folder)
m_config_folder = config_folder;
LOG_PRINT_L0("Loading blockchain...");
const std::string filename = m_config_folder + "/" CRYPTONOTE_BLOCKCHAINDATA_FILENAME;
if(!tools::unserialize_obj_from_file(*this, filename))
if(tools::unserialize_obj_from_file(*this, filename))
{
// checkpoints
// mainchain
for (size_t height=0; height < m_blocks.size(); ++height)
{
CHECK_AND_ASSERT_MES((!m_checkpoints.is_in_checkpoint_zone(height)) || m_checkpoints.check_block(height,get_block_hash(m_blocks[height].bl)),false,"checkpoint fail, blockchain.bin invalid");
}
// check alt chains
#if 0
// doesn't work when a checkpoint is added and there are already alt chains. However, the rest of the blockchain code suffers from the same issue, so ignore for now
// see issue #118
BOOST_FOREACH(blocks_ext_by_hash::value_type& alt_block, m_alternative_chains)
{
CHECK_AND_ASSERT_MES(m_checkpoints.is_alternative_block_allowed(m_blocks.size()-1,alt_block.second.height),false,"stored alternative block not allowed, blockchain.bin invalid");
}
#endif
}
else
{
LOG_PRINT_L0("Can't load blockchain storage from file, generating genesis block.");
block bl = boost::value_initialized<block>();
@ -743,7 +764,7 @@ bool blockchain_storage::handle_alternative_block(const block& b, const crypto::
return false;
}
//block is not related with head of main chain
//Block is not related with head of main chain
//first of all - look in alternative chains container
auto it_main_prev = m_blocks_index.find(b.prev_id);
auto it_prev = m_alternative_chains.find(b.prev_id);

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@ -42,6 +42,10 @@ namespace cryptonote {
ADD_CHECKPOINT(29556, "53c484a8ed91e4da621bb2fa88106dbde426fe90d7ef07b9c1e5127fb6f3a7f6");
ADD_CHECKPOINT(50000, "0fe8758ab06a8b9cb35b7328fd4f757af530a5d37759f9d3e421023231f7b31c");
ADD_CHECKPOINT(80000, "a62dcd7b536f22e003ebae8726e9e7276f63d594e264b6f0cd7aab27b66e75e3");
ADD_CHECKPOINT(202612, "bbd604d2ba11ba27935e006ed39c9bfdd99b76bf4a50654bc1e1e61217962698");
ADD_CHECKPOINT(202613, "e2aa337e78df1f98f462b3b1e560c6b914dec47b610698b7b7d1e3e86b6197c2"); // from chainradar; verify this
ADD_CHECKPOINT(202614, "c29e3dc37d8da3e72e506e31a213a58771b24450144305bcba9e70fa4d6ea6fb"); // from chainradar; verify this
ADD_CHECKPOINT(205000, "5d3d7a26e6dc7535e34f03def711daa8c263785f73ec1fadef8a45880fde8063"); // from chainradar; verify this
return true;
}
}

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@ -635,10 +635,22 @@ namespace cryptonote
if (string_tools::pod_to_hex(block_blob_hash) == correct_blob_hash_202612)
{
res = string_tools::hex_to_pod(existing_block_id_202612);
string_tools::hex_to_pod(existing_block_id_202612, res);
return true;
}
return get_object_hash(get_block_hashing_blob(b), res);
bool hash_result = get_object_hash(get_block_hashing_blob(b), res);
if (hash_result)
{
// make sure that we aren't looking at a block with the 202612 block id but not the correct blobdata
if (string_tools::pod_to_hex(res) == existing_block_id_202612)
{
LOG_ERROR("Block with block id for 202612 but incorrect block blob hash found!");
res = null_hash;
return false;
}
}
return hash_result;
}
//---------------------------------------------------------------
crypto::hash get_block_hash(const block& b)
@ -677,6 +689,13 @@ namespace cryptonote
//---------------------------------------------------------------
bool get_block_longhash(const block& b, crypto::hash& res, uint64_t height)
{
// block 202612 bug workaround
const std::string longhash_202612 = "84f64766475d51837ac9efbef1926486e58563c95a19fef4aec3254f03000000";
if (height == 202612)
{
string_tools::hex_to_pod(longhash_202612, res);
return true;
}
block b_local = b; //workaround to avoid const errors with do_serialize
blobdata bd = get_block_hashing_blob(b);
crypto::cn_slow_hash(bd.data(), bd.size(), res);