On 12/9/19 8:15 PM, li zi wrote:
Hi All, We are using gcc in our projects and we found some of the C standard functions (like memcpy, strcpy) used in gcc may induce security vulnerablities like buffer overflow. Currently we have not found any instances which causes such issues. But we feel better to change these calls to Cll Annex K Bounds-checking interfaces like memcpy_s, strcpy_s etc. By defining a secure calls method (list of func pointers) and allowing application to register the method. I understand that this affects performance because of return value check added for xxxx_s calls, but this will relieve overflow kind of issues from code. And also currently using bounds-checking interfaces is a general industry practice. Please share your opinion on it, and if any discussion happened in community to do some changes in future.
GCC's Object Size Checking is a non-intrusive solution to the problem. It avoids the considerable risk of introducing bugs while replacing existing calls with those to the _s functions. The implementation is restricted to constant sizes so its effectiveness is a limited, but we have been discussing enhancing it to non-constant sizes as well, as Clang already does. With that, it should provide protection with an effectiveness comparable to the _s functions but without any of the downsides. (Note that GCC's buffer overflow warnings are not subject to the same limitation.) Besides Object Size Checking, I would suggest making use of the new attribute access. It lets GCC detect (though not prevent) out-of-bounds accesses by calls to user-defined functions decorated with the attribute. Martin https://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
