fedora 24
format weakness #61


Weakness Breakdown


A format string exploit occurs when the data of an input string is evaluated as a command by the program. This class of attacks is very similar to buffer overflows since an attacker could execute code, read the stack or cause new behaviors that compromise security. Learn more about format string attacks on OWASP attack index.

Warning code(s):

If format strings can be influenced by an attacker, they can be exploited.

File Name:



The highlighted line of code below is the trigger point of this particular Fedora 24 format weakness.

   - Daemon startup and status notification
  - Detection of systemd boots

  You may compile this with -DDISABLE_SYSTEMD to disable systemd
  support. This makes all those calls NOPs that are directly related to
  systemd (i.e. only sd_is_xxx() will stay useful).

  Since this is drop-in code we don't want any of our symbols to be
  exported in any case. Hence we declare hidden visibility for all of

  You may find an up-to-date version of these source files online:


  This should compile on non-Linux systems, too, but with the
  exception of the sd_is_xxx() calls all functions will become NOPs.

  See sd-daemon(7) for more information.

#ifndef _sd_printf_attr_
#if __GNUC__ >= 4
#define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
#define _sd_printf_attr_(a,b)

#ifndef _sd_hidden_
#if (__GNUC__ >= 4) && !defined(SD_EXPORT_SYMBOLS)
#define _sd_hidden_ __attribute__ ((visibility("hidden")))
#define _sd_hidden_

  Log levels for usage on stderr:

          fprintf(stderr, SD_NOTICE "Hello World!\n");

  This is similar to printk() usage in the kernel.
#define SD_EMERG   "<0>"  /* system is unusable */
#define SD_ALERT   "<1>"  /* action must be taken immediately */
#define SD_CRIT    "<2>"  /* critical conditions */
#define SD_ERR     "<3>"  /* error conditions */
#define SD_WARNING "<4>"  /* warning conditions */ 

The registered trademark Linux® is used pursuant to a sublicense from the Linux Foundation, the exclusive licensee of Linus Torvalds, owner of the mark on a world­wide basis.