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Buffer overrun in function parameter

This commit is contained in:
Daniel Marjamäki 2008-03-23 16:18:31 +00:00
parent 44bee90d82
commit 4c17dd9499
4 changed files with 246 additions and 144 deletions
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317
CheckBufferOverrun.cpp
View File

@ -155,6 +155,172 @@ static void CheckBufferOverrun_DynamicData()
// Buffer overrun.. // Buffer overrun..
//--------------------------------------------------------------------------- //---------------------------------------------------------------------------
static void CheckBufferOverrun_LocalVariable_CheckScope( const TOKEN *tok, const char varname[], const int size, const int total_size )
{
int indentlevel = 0;
for ( ; tok; tok = tok->next )
{
if (tok->str[0]=='{')
{
indentlevel++;
continue;
}
if (tok->str[0]=='}')
{
indentlevel--;
if ( indentlevel < 0 )
return;
continue;
}
// Array index..
if (strcmp(tok->str,varname)==0 && match(tok->next,"[ num ]"))
{
const char *str = getstr(tok, 2);
if (strtol(str, NULL, 10) >= size)
{
std::ostringstream ostr;
ostr << FileLine(tok) << ": Array index out of bounds";
ReportErr(ostr.str());
}
continue;
}
// memset, memcmp, memcpy, strncpy, fgets..
if (strcmp(tok->str,"memset")==0 ||
strcmp(tok->str,"memcpy")==0 ||
strcmp(tok->str,"memmove")==0 ||
strcmp(tok->str,"memcmp")==0 ||
strcmp(tok->str,"strncpy")==0 ||
strcmp(tok->str,"fgets")==0 )
{
if (match(tok->next,"( var , num , num )") ||
match(tok->next,"( var , var , num )") )
{
const char *var1 = getstr(tok, 2);
const char *var2 = getstr(tok, 4);
const char *num = getstr(tok, 6);
if ( atoi(num)>total_size &&
(strcmp(var1,varname)==0 ||
strcmp(var2,varname)==0 ) )
{
std::ostringstream ostr;
ostr << FileLine(tok) << ": Buffer overrun";
ReportErr(ostr.str());
}
}
continue;
}
// Loop..
if ( match(tok, "for ( var = 0 ;") )
{
const char *strindex = 0;
int value = 0;
if (match(tok,"for ( var = 0 ; var < num ; var + + )") ||
match(tok,"for ( var = 0 ; var < num ; + + var )") )
{
strindex = getstr(tok,2);
value = atoi(getstr(tok,8));
}
else if (match(tok,"for ( var = 0 ; var <= num ; var + + )") ||
match(tok,"for ( var = 0 ; var <= num ; + + var )") )
{
strindex = getstr(tok,2);
value = 1 + atoi(getstr(tok,8));
}
if (strindex && value>(int)size)
{
const TOKEN *tok2 = tok;
while (tok2 && strcmp(tok2->str,")"))
tok2 = tok2->next;
if (!tok2)
break;
tok2 = tok2->next;
if (tok2->str[0] == '{')
tok2 = tok2->next;
while (tok2 && !strchr(";}",tok2->str[0]))
{
if ( match( tok2, "var [ var ]" ) &&
strcmp(tok2->str,varname)==0 &&
strcmp(getstr(tok2,2),strindex)==0 )
{
std::ostringstream ostr;
ostr << FileLine(tok2) << ": Buffer overrun";
ReportErr(ostr.str());
break;
}
tok2 = tok2->next;
}
}
continue;
}
// Writing data into array..
if (match(tok,"strcpy ( var , "))
{
int len = 0;
if (strcmp(getstr(tok, 2), varname) == 0)
{
const char *str = getstr(tok, 4);
if (str[0] == '\"')
{
while (*str)
{
if (*str=='\\')
str++;
str++;
len++;
}
}
}
if (len > 2 && len >= (int)size + 2)
{
std::ostringstream ostr;
ostr << FileLine(tok) << ": Buffer overrun";
ReportErr(ostr.str());
}
continue;
}
// Function call..
// Todo: This is just experimental. It must be more versatile..
if ( match( tok, "var ( var )" ) && strcmp(varname, getstr(tok,2)) == 0 )
{
// Find function..
const TOKEN *ftok = FindFunction( tok->str );
if ( ! ftok )
continue;
// Parse head of function..
while ( ftok )
{
if ( match( ftok, "var ) {" ) )
{
CheckBufferOverrun_LocalVariable_CheckScope( gettok(ftok,3), ftok->str, size, total_size );
break;
}
if ( ftok->str[0] == '{' )
break;
ftok = ftok->next;
}
}
}
}
static void CheckBufferOverrun_LocalVariable() static void CheckBufferOverrun_LocalVariable()
{ {
int indentlevel = 0; int indentlevel = 0;
@ -166,152 +332,15 @@ static void CheckBufferOverrun_LocalVariable()
else if (tok->str[0]=='}') else if (tok->str[0]=='}')
indentlevel--; indentlevel--;
else if (indentlevel > 0) else if (indentlevel > 0 && match(tok, "type var [ num ] ;"))
{ {
// Declaring array.. const char *varname = getstr(tok,1);
if (match(tok, "type var [ num ] ;")) unsigned int size = strtoul(getstr(tok,3), NULL, 10);
{ int total_size = size * SizeOfType(tok->str);
const char *varname = getstr(tok,1); if (total_size == 0)
unsigned int size = strtoul(getstr(tok,3), NULL, 10); continue;
int total_size = size * SizeOfType(tok->str);
if (total_size == 0)
continue;
int _indentlevel = indentlevel;
for (const TOKEN *tok2 = gettok(tok,5); tok2; tok2 = tok2->next)
{
if (tok2->str[0]=='{')
{
_indentlevel++;
}
else if (tok2->str[0]=='}')
{
_indentlevel--;
if (_indentlevel < indentlevel)
break;
}
else
{
// Array index..
if (strcmp(tok2->str,varname)==0 && match(tok2->next,"[ num ]"))
{
const char *str = getstr(tok2, 2);
if (strtoul(str, NULL, 10) >= size)
{
std::ostringstream ostr;
ostr << FileLine(tok2) << ": Array index out of bounds";
ReportErr(ostr.str());
}
}
CheckBufferOverrun_LocalVariable_CheckScope( gettok(tok,5), varname, size, total_size );
// memset, memcmp, memcpy, strncpy, fgets..
if (strcmp(tok2->str,"memset")==0 ||
strcmp(tok2->str,"memcpy")==0 ||
strcmp(tok2->str,"memmove")==0 ||
strcmp(tok2->str,"memcmp")==0 ||
strcmp(tok2->str,"strncpy")==0 ||
strcmp(tok2->str,"fgets")==0 )
{
if (match(tok2->next,"( var , num , num )") ||
match(tok2->next,"( var , var , num )") )
{
const char *var1 = getstr(tok2, 2);
const char *var2 = getstr(tok2, 4);
const char *num = getstr(tok2, 6);
if ( atoi(num)>total_size &&
(strcmp(var1,varname)==0 ||
strcmp(var2,varname)==0 ) )
{
std::ostringstream ostr;
ostr << FileLine(tok2) << ": Buffer overrun";
ReportErr(ostr.str());
}
}
}
// Loop..
const char *strindex = 0;
int value = 0;
if ( match(tok2, "for ( var = 0 ;") )
{
if (match(tok2,"for ( var = 0 ; var < num ; var + + )"))
{
strindex = getstr(tok2,2);
value = atoi(getstr(tok2,8));
}
else if (match(tok2,"for ( var = 0 ; var <= num ; var + + )"))
{
strindex = getstr(tok2,2);
value = 1 + atoi(getstr(tok2,8));
}
else if (match(tok2,"for ( var = 0 ; var < num ; + + var )"))
{
strindex = getstr(tok2,2);
value = atoi(getstr(tok2,8));
}
else if (match(tok2,"for ( var = 0 ; var <= num ; + + var )"))
{
strindex = getstr(tok2,2);
value = 1 + atoi(getstr(tok2,8));
}
}
if (strindex && value>(int)size)
{
const TOKEN *tok3 = tok2;
while (tok3 && strcmp(tok3->str,")"))
tok3 = tok3->next;
if (!tok3)
break;
tok3 = tok3->next;
if (tok3->str[0] == '{')
tok3 = tok3->next;
while (tok3 && !strchr(";}",tok3->str[0]))
{
if (strcmp(tok3->str,varname)==0 &&
strcmp(getstr(tok3,1),"[")==0 &&
strcmp(getstr(tok3,2),strindex)==0 &&
strcmp(getstr(tok3,3),"]")==0 )
{
std::ostringstream ostr;
ostr << FileLine(tok3) << ": Buffer overrun";
ReportErr(ostr.str());
break;
}
tok3 = tok3->next;
}
}
// Writing data into array..
if (match(tok2,"strcpy ( var , "))
{
int len = 0;
if (strcmp(getstr(tok2, 2), varname) == 0)
{
const char *str = getstr(tok2, 4);
if (str[0] == '\"')
{
while (*str)
{
if (*str=='\\')
str++;
str++;
len++;
}
}
}
if (len > 2 && len >= (int)size + 2)
{
std::ostringstream ostr;
ostr << FileLine(tok2) << ": Buffer overrun";
ReportErr(ostr.str());
}
}
}
}
}
} }
} }
} }

37
CommonCheck.cpp
View File

@ -58,3 +58,40 @@ bool IsStandardType(const char str[])
} }
//--------------------------------------------------------------------------- //---------------------------------------------------------------------------
const TOKEN *FindFunction( const char funcname[] )
{
int indentlevel = 0;
for ( const TOKEN *tok = tokens; tok; tok = tok->next )
{
if ( tok->str[0] == '{' )
indentlevel++;
else if ( tok->str[0] == '}' )
indentlevel--;
else if (indentlevel==0 && IsName(tok->str))
{
// Check if this is the first token of a function implementation..
bool haspar = false;
bool foundname = false;
for ( const TOKEN *tok2 = tok; tok2; tok2 = tok2->next )
{
haspar |= bool(tok2->str[0] == '(');
if ( ! haspar && match(tok2,"var (") )
{
if ( strcmp(funcname, tok2->str) != 0 )
break;
foundname = true;
}
if ( tok2->str[0] == ';' )
break;
if ( tok2->str[0] == '{' )
break;
if ( foundname && haspar && match(tok2, ") {") )
return tok;
}
}
}
return NULL;
}

2
CommonCheck.h
View File

@ -21,5 +21,7 @@ bool IsNumber(const char str[]);
bool IsStandardType(const char str[]); bool IsStandardType(const char str[]);
const TOKEN *FindFunction( const char funcname[] );
//--------------------------------------------------------------------------- //---------------------------------------------------------------------------
#endif #endif

34
tests.cpp
View File

@ -422,6 +422,40 @@ static void buffer_overrun()
check( CheckBufferOverrun, __LINE__, test10, "[test.cpp:8]: Array index out of bounds\n" ); check( CheckBufferOverrun, __LINE__, test10, "[test.cpp:8]: Array index out of bounds\n" );
const char test11[] = "static void memclr( char *data )\n"
"{\n"
" data[10] = 0;\n"
"}\n"
"\n"
"static void f()\n"
"{\n"
" char str[5];\n"
" memclr( str ); // ERROR\n"
"}\n";
check( CheckBufferOverrun, __LINE__, test11, "[test.cpp:3]: Array index out of bounds\n" );
// TODO
/*
const char test11[] = "static void memclr( char *data, const int bytes )\n"
"{\n"
" for (int i = 0; i < bytes; i++)\n"
" data[i] = 0;\n"
"}\n"
"\n"
"static void f()\n"
"{\n"
" char str[5];\n"
" memclr( str, 5 ); // OK\n"
" memclr( str+1, 5 ); // ERROR\n"
" memclr( str, 6 ); // ERROR\n"
"}\n";
check( CheckBufferOverrun, __LINE__, test11, "" );
*/
// TODO // TODO
/* /*
const char test[] = "class Fred\n" const char test[] = "class Fred\n"