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Fix #744 (False positive: (possible error) Array index out of bounds) 

http://sourceforge.net/apps/trac/cppcheck/ticket/744
This commit is contained in:
Reijo Tomperi 2009-09-30 15:51:33 +03:00
parent 6ed727564c
commit ec44f8f6c7
2 changed files with 32 additions and 2 deletions
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18
src/checkbufferoverrun.cpp
View File

@ -273,13 +273,27 @@ void CheckBufferOverrun::checkScope(const Token *tok, const char *varname[], con
Token::Match(tok3, "%varid% = %num% + %varid% )", counter_varid)) Token::Match(tok3, "%varid% = %num% + %varid% )", counter_varid))
{ {
const int num = std::atoi(tok3->strAt(2)); const int num = std::atoi(tok3->strAt(2));
if (num > value)
// We have for example code: "for(i=2;i<22;i+=6)
// We can calculate that max value for i is 20, not 21
// 21-2 = 19
// 19/6 = 3
// 6*3+2 = 20
long max = MathLib::toLongNumber(max_counter_value);
long min = MathLib::toLongNumber(min_counter_value);
max = ((max - min) / num) * num + min;
max_counter_value = MathLib::toString<long>(max);
if (max <= size)
condition_out_of_bounds = false; condition_out_of_bounds = false;
} }
else if (Token::Match(tok3, "%varid% = %varid% + %num% )", counter_varid)) else if (Token::Match(tok3, "%varid% = %varid% + %num% )", counter_varid))
{ {
const int num = std::atoi(tok3->strAt(4)); const int num = std::atoi(tok3->strAt(4));
if (num > value) long max = MathLib::toLongNumber(max_counter_value);
long min = MathLib::toLongNumber(min_counter_value);
max = ((max - min) / num) * num + min;
max_counter_value = MathLib::toString<long>(max);
if (max <= size)
condition_out_of_bounds = false; condition_out_of_bounds = false;
} }
else if (! Token::Match(tok3, "++| %varid% ++| )", counter_varid)) else if (! Token::Match(tok3, "++| %varid% ++| )", counter_varid))

16
test/testbufferoverrun.cpp
View File

@ -495,6 +495,22 @@ private:
" a[i*2] = i;\n" " a[i*2] = i;\n"
"}\n"); "}\n");
ASSERT_EQUALS("[test.cpp:5]: (possible error) Array index out of bounds\n", errout.str()); ASSERT_EQUALS("[test.cpp:5]: (possible error) Array index out of bounds\n", errout.str());
check("void f()\n"
"{\n"
" int a[12];\n"
" for (int i = 0; i < 12; i+=6)\n"
" a[i+5] = i;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f()\n"
"{\n"
" int a[12];\n"
" for (int i = 0; i < 12; i+=6)\n"
" a[i+6] = i;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5]: (possible error) Array index out of bounds\n", errout.str());
} }
void buffer_overrun_1() void buffer_overrun_1()