c++cprintffortify-source

Disable using __sprintf_chk()

I observe that a c++ program uses sprintf, where this sprintf implicitly invokes __sprintf_chk(). This __sprintf_chk() seems to check buffer overflow by examining stack frames.

For my research purpose, I wonder if it is possible to disable using __sprintf_chk()?

Solution

  • Try to replace all calls to sprintf in your program from this:

     sprintf(params...);

    into

     (sprintf)(params...);

    This will disable any preprocessor-based sprintf-changing (* only if sprintf was changed using function-like macro like in the case of __sprintf_chk).

    For gcc there are options -fno-stack-protector -fno-mudflap. May be also -D_FORTIFY_SOURCE=0 (for any glibc)

    For Ubuntu and debian there are pages with security features list: http://wiki.debian.org/Hardening and https://wiki.ubuntu.com/Security/Features Some used compiler flags are listed here https://wiki.ubuntu.com/ToolChain/CompilerFlags

    And there is a paper about SSP (stack-protector) and Fortify_source (glibc): http://www.linuxfromscratch.org/hints/downloads/files/ssp.txt

    PS: the same for __fgets_chk __gets_chk __printf_chk __fprintf_chk __vprintf_chk __vfprintf_chk __vsprintf_chk __wmemcpy_chk __wmemmove_chk __wmempcpy_chk __wmemset_chk __wcscpy_chk __wcpcpy_chk __wcsncpy_chk __wcpncpy_chk __wcscat_chk __wcsncat_chk __swprintf_chk __vswprintf_chk __fwprintf_chk __wprintf_chk __vfwprintf_chk __vwprintf_chk __fgetws_chk __wcrtomb_chk __mbsrtowcs_chk __wcsrtombs_chk __mbsnrtowcs_chk __wcsnrtombs_chk __memcpy_chk __memmove_chk __mempcpy_chk __memset_chk __strcpy_chk __strncpy_chk __stpncpy_chk __strcat_chk and some others