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Fixing further bugs with test_access, improved access_details interface.

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This commit is contained in:
Can Bölük 2020-08-23 07:07:11 +02:00
parent 0a1d015eba
commit 0ec97f0c17
2 changed files with 99 additions and 70 deletions
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148
VTIL-Architecture/symex/variable.cpp
View file

@ -180,13 +180,14 @@ namespace vtil::symbolic
//
static access_details test_access( const variable& var, const il_const_iterator& it, tracer* tracer, bool cwrite, bool cread, bool xblock )
{
access_details result = {};
// If variable is of register type:
//
if ( auto reg = std::get_if<variable::register_t>( &var.descriptor ) )
{
// Iterate each operand:
//
access_details details;
for ( int i = 0; i < it->base->operand_count(); i++ )
{
// Skip if not register.
@ -209,14 +210,13 @@ namespace vtil::symbolic
// Append access details.
//
details += {
result += {
.bit_offset = ref_reg.bit_offset - reg->bit_offset,
.bit_count = ref_reg.bit_count,
.read = it->base->operand_types[ i ] != operand_type::write,
.write = it->base->operand_types[ i ] >= operand_type::write
};
}
return details;
}
// If variable is of memory type:
//
@ -255,16 +255,20 @@ namespace vtil::symbolic
// If offset is unknown, return as is.
//
if ( details.is_unknown() )
return details;
// Check if within boundaries, set bit count and return if so.
//
bitcnt_t low_offset = details.bit_offset;
bitcnt_t high_offset = low_offset + it->access_size();
if ( low_offset < mem->bit_count && high_offset > 0 )
{
details.bit_count = it->access_size();
return details;
result += details;
}
else
{
// Check if within boundaries, set bit count and return if so.
//
bitcnt_t low_offset = details.bit_offset;
bitcnt_t high_offset = low_offset + it->access_size();
if ( low_offset < mem->bit_count && high_offset > 0 )
{
details.bit_count = it->access_size();
result += details;
}
}
}
}
@ -288,13 +292,15 @@ namespace vtil::symbolic
//
if ( reg.is_stack_pointer() )
{
if ( !cread ) return {};
return {
.bit_offset = 0,
.bit_count = reg.bit_count,
.read = true,
.write = false
};
if ( !cread )
{
result += {
.bit_offset = 0,
.bit_count = reg.bit_count,
.read = true,
.write = false
};
}
}
// If exiting the virtual machine:
@ -309,7 +315,7 @@ namespace vtil::symbolic
{
if ( retval.overlaps( reg ) )
{
return {
result += {
.bit_offset = retval.bit_offset - reg.bit_offset,
.bit_count = retval.bit_count,
.read = true,
@ -325,7 +331,7 @@ namespace vtil::symbolic
{
for ( const register_desc& retval : it.block->owner->routine_convention.volatile_registers )
if ( retval.overlaps( reg ) )
return { .bit_offset = 0, .bit_count = reg.bit_count, .read = false, .write = true };
result += { .bit_offset = 0, .bit_count = reg.bit_count, .read = false, .write = true };
}
// If virtual register, indicate discarded:
@ -333,67 +339,75 @@ namespace vtil::symbolic
if ( cwrite )
{
if ( reg.is_virtual() )
return { .bit_offset = 0, .bit_count = reg.bit_count, .read = false, .write = true };
result += { .bit_offset = 0, .bit_count = reg.bit_count, .read = false, .write = true };
}
// Otherwise indicate read from.
//
if ( !cread ) return {};
return {
.bit_offset = 0,
.bit_count = reg.bit_count,
.read = true,
.write = false
};
if ( cread )
{
result += {
.bit_offset = 0,
.bit_count = reg.bit_count,
.read = true,
.write = false
};
}
}
// If not only looking for read access, check if register is written to.
// If invoking external routine:
//
access_details wdetails = {};
if ( cwrite )
else
{
for ( const register_desc& param : cc.volatile_registers )
// If not only looking for read access, check if register is written to.
//
access_details wdetails = {};
if ( cwrite )
{
if ( param.overlaps( reg ) )
for ( const register_desc& param : cc.volatile_registers )
{
wdetails.bit_offset = param.bit_offset - reg.bit_offset;
wdetails.bit_count = param.bit_count;
wdetails.write = true;
break;
if ( param.overlaps( reg ) )
{
wdetails.bit_offset = param.bit_offset - reg.bit_offset;
wdetails.bit_count = param.bit_count;
wdetails.write = true;
break;
}
}
for ( const register_desc& retval : cc.retval_registers )
{
if ( retval.overlaps( reg ) )
{
wdetails.bit_offset = retval.bit_offset - reg.bit_offset;
wdetails.bit_count = retval.bit_count;
wdetails.write = true;
break;
}
}
}
for ( const register_desc& retval : cc.retval_registers )
// If not only looking for write access, check if register is read from.
//
access_details rdetails = {};
if ( cread )
{
if ( retval.overlaps( reg ) )
for ( const register_desc& param : cc.param_registers )
{
wdetails.bit_offset = retval.bit_offset - reg.bit_offset;
wdetails.bit_count = retval.bit_count;
wdetails.write = true;
break;
if ( param.overlaps( reg ) )
{
rdetails.bit_offset = param.bit_offset - reg.bit_offset;
rdetails.bit_count = param.bit_count;
rdetails.read = true;
break;
}
}
}
// Merge rdetails and wdetails into result.
//
result += wdetails + rdetails;
}
// If not only looking for write access, check if register is read from.
//
access_details rdetails = {};
if ( cread )
{
for ( const register_desc& param : cc.param_registers )
{
if ( param.overlaps( reg ) )
{
rdetails.bit_offset = param.bit_offset - reg.bit_offset;
rdetails.bit_count = param.bit_count;
rdetails.read = true;
break;
}
}
}
// Merge rdetails and wdetails, return.
//
return wdetails + rdetails;
}
// If variable is memory:
//
@ -419,7 +433,7 @@ namespace vtil::symbolic
access_details details;
fill_displacement( &details, mem.base, pointer{ std::move( limit ) }, tracer, xblock );
if ( !details.is_unknown() && ( details.bit_offset + var.bit_count() ) <= 0 )
return { .bit_offset = 0, .bit_count = var.bit_count(), .read = false, .write = true };
result += { .bit_offset = 0, .bit_count = var.bit_count(), .read = false, .write = true };
}
}
@ -430,9 +444,9 @@ namespace vtil::symbolic
}
}
// No access case.
// Return result.
//
return {};
return result;
}
// Constructs by iterator and the variable descriptor itself.

21
VTIL-Architecture/symex/variable.hpp
View file

@ -91,11 +91,26 @@ namespace vtil::symbolic
return {
.bit_offset = bmin,
.bit_count = bmax - bmin,
.read = read || o.read,
.write = write || o.write
.read = read || o.read,
.write = write || o.write,
.unknown = unknown || o.unknown
};
}
access_details& operator+=( const access_details& o ) { return *this = o + *this; }
access_details& operator+=( const access_details& o ) { return *this = ( o + *this ); }
// String conversion.
//
std::string to_string() const
{
if ( bit_count == 0 ) return format::str( "None" );
const char* str;
if ( read && write ) str = "RW";
else if ( read ) str = "R";
else if ( write ) str = "W";
else str = "?";
if ( unknown ) return format::str( "Unknown [%s]\n", str );
return format::str( "[%s] @%d:%d\n", str, bit_count, bit_offset );
}
};
// A pseudo single-static-assignment variable describing the state of a