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Prevent oob on LSET::FmtHex call when BITSET size is not a multiple of 4 (which it isn't usually)

This commit is contained in:
Mark Roszko 2019-12-20 21:04:34 -05:00 committed by Jon Evans
parent 25a302758e
commit a418242ca7
1 changed files with 9 additions and 7 deletions
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16
common/lset.cpp
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@ -286,19 +286,21 @@ std::string LSET::FmtHex() const
static const char hex[] = "0123456789abcdef"; static const char hex[] = "0123456789abcdef";
unsigned nibble_count = ( size() + 3 ) / 4; size_t nibble_count = ( size() + 3 ) / 4;
for( unsigned nibble = 0; nibble < nibble_count; ++nibble ) for( size_t nibble = 0; nibble < nibble_count; ++nibble )
{ {
unsigned ndx = 0; unsigned int ndx = 0;
// test 4 consecutive bits and set ndx to 0-15: // test 4 consecutive bits and set ndx to 0-15
for( unsigned nibble_bit = 0; nibble_bit < 4; ++nibble_bit ) for( int nibble_bit = 0; nibble_bit < 4; ++nibble_bit )
{ {
if( ( nibble_bit + nibble * 4 ) >= size() ) size_t nibble_pos = nibble_bit + ( nibble * 4 );
// make sure it's not extra bits that dont exist in the bitset but need to in the hex format
if( nibble_pos >= size() )
break; break;
if( (*this)[nibble_bit + nibble * 4] ) if( ( *this )[nibble_pos] )
ndx |= ( 1 << nibble_bit ); ndx |= ( 1 << nibble_bit );
} }