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Fix #694 (False (possible error) Buffer overrun with %-1s) 

ashim2009 did most of the work
http://sourceforge.net/apps/trac/cppcheck/ticket/694
This commit is contained in:
Reijo Tomperi 2009-10-11 21:36:22 +03:00
parent bcc77f7f8b
commit 59aad35137
2 changed files with 39 additions and 118 deletions
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154
src/checkbufferoverrun.cpp
View File

@ -773,9 +773,6 @@ void CheckBufferOverrun::bufferOverrun()
int CheckBufferOverrun::countSprintfLength(const std::string &input_string, const std::list<const Token*> &parameters) int CheckBufferOverrun::countSprintfLength(const std::string &input_string, const std::list<const Token*> &parameters)
{ {
int flag = 1; int flag = 1;
int second_flag = 0; // This is to check for % int second_flag = 0; // This is to check for %
int input_string_size = 0; int input_string_size = 0;
@ -898,137 +895,60 @@ int CheckBufferOverrun::countSprintfLength(const std::string &input_string, cons
void CheckBufferOverrun::checkSprintfCall(const Token *tok, int size) void CheckBufferOverrun::checkSprintfCall(const Token *tok, int size)
{ {
if (0) std::list<const Token*> parameters;
if (tok->tokAt(5)->str() == ",")
{ {
std::list<const Token*> parameters; const Token *end = tok->next()->link();
if (tok->tokAt(5)->str() == ",") for (const Token *tok2 = tok->tokAt(5); tok2 && tok2 != end; tok2 = tok2->next())
{ {
const Token *end = tok->next()->link(); if (Token::Match(tok2, ", %any% [,)]"))
for (const Token *tok2 = tok->tokAt(6); tok2 && tok2 != end; tok2 = tok2->next())
{ {
if (Token::Match(tok2, ", %any% [,)]"))
{
if (Token::Match(tok2->next(), "%str%"))
parameters.push_back(tok2->next());
else if (Token::Match(tok2->next(), "%num%")) if (Token::Match(tok2->next(), "%str%"))
parameters.push_back(tok2->next()); parameters.push_back(tok2->next());
// TODO, get value of the variable if possible and use that instead of 0 else if (Token::Match(tok2->next(), "%num%"))
else parameters.push_back(tok2->next());
parameters.push_back(0);
} // TODO, get value of the variable if possible and use that instead of 0
else else
{
// Parameter is more complex, than just a value or variable. Ignore it for now
// and skip to next token.
parameters.push_back(0); parameters.push_back(0);
int ind = 0; }
for (const Token *tok3 = tok2->next(); tok3; tok3 = tok3->next()) else
{
// Parameter is more complex, than just a value or variable. Ignore it for now
// and skip to next token.
parameters.push_back(0);
int ind = 0;
for (const Token *tok3 = tok2->next(); tok3; tok3 = tok3->next())
{
if (tok3->str() == "(")
++ind;
else if (tok3->str() == ")")
{ {
if (tok3->str() == "(") --ind;
++ind; if (ind < 0)
else if (tok3->str() == ")")
{
--ind;
if (ind < 0)
break;
}
else if (ind == 0 && tok3->str() == ",")
{
tok2 = tok3->previous();
break; break;
}
} }
if (ind < 0) else if (ind == 0 && tok3->str() == ",")
{
tok2 = tok3->previous();
break; break;
}
} }
}
}
int len = countSprintfLength(tok->tokAt(4)->strValue(), parameters); if (ind < 0)
if (len > size) break;
{ }
bufferOverrun(tok);
} }
} }
else
int len = countSprintfLength(tok->tokAt(4)->strValue(), parameters);
if (len > size)
{ {
int len = -2; bufferOverrun(tok);
// check format string
const char *fmt = tok->strAt(4);
while (*fmt)
{
if (*fmt == '\\')
{
++fmt;
}
else if (*fmt == '%')
{
++fmt;
// skip field width
while (std::isdigit(*fmt))
{
++fmt;
}
// FIXME: better handling for format specifiers
++fmt;
continue;
}
++fmt;
++len;
}
if (len >= (int)size)
{
bufferOverrun(tok);
}
// check arguments (if they exists)
if (tok->tokAt(5)->str() == ",")
{
len = 0;
const Token *end = tok->next()->link();
bool argumentAlreadyChecked = false;
int lastCheckedArgumentMaxSize = 0;
for (const Token *tok2 = tok->tokAt(6); tok2 && tok2 != end; tok2 = tok2->next())
{
if (tok2->str() == ",")
{
argumentAlreadyChecked = false;
lastCheckedArgumentMaxSize = 0;
}
else if (Token::Match(tok2, "%str%"))
{
int argumentSize = static_cast<int>(Token::getStrLength(tok2));
if (argumentAlreadyChecked == false)
{
lastCheckedArgumentMaxSize = argumentSize;
len += argumentSize;
argumentAlreadyChecked = true;
}
else if (argumentSize > lastCheckedArgumentMaxSize)
{
// when sprintf() argument is ternary
// operation we may have two and more
// strings as argument. In this case we
// use length of longest string.
len += (argumentSize - lastCheckedArgumentMaxSize);
lastCheckedArgumentMaxSize = argumentSize;
}
}
}
if (len >= (int)size)
{
bufferOverrun(tok);
}
}
} }
} }

3
test/testbufferoverrun.cpp
View File

@ -860,7 +860,7 @@ private:
" char buf[3];\n" " char buf[3];\n"
" sprintf(buf, \"%s\", condition ? \"11\" : \"222\");\n" " sprintf(buf, \"%s\", condition ? \"11\" : \"222\");\n"
"}\n"); "}\n");
ASSERT_EQUALS("[test.cpp:4]: (possible error) Buffer overrun\n", errout.str()); TODO_ASSERT_EQUALS("[test.cpp:4]: (possible error) Buffer overrun\n", errout.str());
} }
void snprintf1() void snprintf1()
@ -1023,6 +1023,7 @@ private:
ASSERT_EQUALS(2, CheckBufferOverrun::countSprintfLength("%1d", unknownParameter)); ASSERT_EQUALS(2, CheckBufferOverrun::countSprintfLength("%1d", unknownParameter));
ASSERT_EQUALS(3, CheckBufferOverrun::countSprintfLength("%2.2d", unknownParameter)); ASSERT_EQUALS(3, CheckBufferOverrun::countSprintfLength("%2.2d", unknownParameter));
ASSERT_EQUALS(1, CheckBufferOverrun::countSprintfLength("%s", unknownParameter)); ASSERT_EQUALS(1, CheckBufferOverrun::countSprintfLength("%s", unknownParameter));
ASSERT_EQUALS(1, CheckBufferOverrun::countSprintfLength("%-s", unknownParameter));
ASSERT_EQUALS(6, CheckBufferOverrun::countSprintfLength("%-5s", unknownParameter)); ASSERT_EQUALS(6, CheckBufferOverrun::countSprintfLength("%-5s", unknownParameter));
ASSERT_EQUALS(2, CheckBufferOverrun::countSprintfLength("\\\"", unknownParameter)); ASSERT_EQUALS(2, CheckBufferOverrun::countSprintfLength("\\\"", unknownParameter));
ASSERT_EQUALS(7, CheckBufferOverrun::countSprintfLength("Hello \0Text", unknownParameter)); ASSERT_EQUALS(7, CheckBufferOverrun::countSprintfLength("Hello \0Text", unknownParameter));