An obsolete weakness occurs when someone uses deprecated or obsolete functions when building a system. As a programming language evolves, some functions occasionally become obsolete.
These functions are considered obsolete on most systems, and very non-portable.
The highlighted line of code below is the trigger point of this particular Centos 6 obsolete weakness.
pid = selftid; #endif } #if __ASSUME_TGKILL || defined __NR_tgkill else /* raise is an async-safe function. It could be called while the fork/vfork function temporarily invalidated the PID field. Adjust for that. */ if (__builtin_expect (pid <= 0, 0)) pid = (pid & INT_MAX) == 0 ? selftid : -pid; #endif #if __ASSUME_TGKILL return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig); #else # ifdef __NR_tgkill int res = INLINE_SYSCALL (tgkill, 3, pid, selftid, sig); if (res != -1 || errno != ENOSYS) return res; # endif return INLINE_SYSCALL (tkill, 2, selftid, sig); #endif } libc_hidden_def (raise) weak_alias (raise, gsignal)