Mitigate Baron SameEdit (CVE-2021-3156) vulnerability

rhel 6
race weakness #489


Weakness Breakdown


A race condition exists when parallel code accesses shared data without proper coordination. An attack that uses a race-condition weakness takes advantage of the unsafe data access to manipulate how one of the parallel sections of code reacts. Even though each process runs as intended, the outcome is unexpected. For example, consider a bank service that depends on an encryption key that it reads from a known location. An independent cryptography service is responsible for generating the key and placing it where the bank is expected to read it in a timely manner. If the bank and cryptography services do not coordinate with each other, then the bank may read a blank encryption key before cryptography writes the key to the location. This can effectively turn off all encryption for the bank without either service, or the administrator, knowing that something has gone wrong.

Warning code(s):

This accepts filename arguments; if an attacker can move those files, a race condition results..

File Name:



The highlighted line of code below is the trigger point of this particular Red Hat Enterprise Linux 6 race weakness.

/* Change the owner of FILE to UID (if UID is not -1) and the group of FILE
   to GID (if GID is not -1).  Follow symbolic links.
   Return 0 if successful, otherwise -1 and errno set.
   See the POSIX:2008 specification
   <  */
#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
#   undef chown
#   define chown rpl_chown
#  endif
_GL_FUNCDECL_RPL (chown, int, (const char *file, uid_t uid, gid_t gid)
                              _GL_ARG_NONNULL ((1)));
_GL_CXXALIAS_RPL (chown, int, (const char *file, uid_t uid, gid_t gid));
# else
#  if !@HAVE_CHOWN@
_GL_FUNCDECL_SYS (chown, int, (const char *file, uid_t uid, gid_t gid)
                              _GL_ARG_NONNULL ((1)));
#  endif
_GL_CXXALIAS_SYS (chown, int, (const char *file, uid_t uid, gid_t gid));
# endif
# undef chown
_GL_WARN_ON_USE (chown, "chown fails to follow symlinks on some systems and "
                 "doesn't treat a uid or gid of -1 on some systems - "
                 "use gnulib module chown for portability");
# endif

/* Automatically included by modules that need a replacement for close.  */
#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
#   undef close
#   define close rpl_close
#  endif
_GL_FUNCDECL_RPL (close, int, (int fd));
_GL_CXXALIAS_RPL (close, int, (int fd));
# else
_GL_CXXALIAS_SYS (close, int, (int fd));
# endif
# undef close
# define close close_used_without_requesting_gnulib_module_close
#elif defined GNULIB_POSIXCHECK 

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