Please examine the following atomic example: #include <iostream> #include <signal.h> #include <sys/signal.h> using std::cout; using std::endl; void handler( int sig, siginfo_t *info, void *ctx ) { cout << "Got " << sig << " signal." << endl; popen( "/bin/ps", "r" ); cout << "Finished." << endl; } int main() { struct sigaction action; action.sa_sigaction = &handler; sigfillset( &action.sa_mask ); action.sa_flags = SA_RESETHAND | SA_SIGINFO | SA_ONSTACK; sigaction( SIGABRT, &action, NULL ); sigaction( SIGQUIT, &action, NULL ); sigaction( SIGILL, &action, NULL ); sigaction( SIGTRAP, &action, NULL ); sigaction( SIGABRT, &action, NULL ); sigaction( SIGFPE, &action, NULL ); sigaction( SIGBUS, &action, NULL ); sigaction( SIGSEGV, &action, NULL ); sigaction( SIGSYS, &action, NULL ); sigaction( SIGXCPU, &action, NULL ); sigaction( SIGXFSZ, &action, NULL ); void *p = ::malloc( 1 ); ::free( p ); ::free( p ); return 0; } With older versions of glibc, this produces: Got 11 signal. Finished. Segmentation fault (core dumped) With newer versions of glibc, this HANGS after producing: *** glibc detected *** double free or corruption (fasttop): 0x0804a008 *** Got 6 signal. The only way to terminate it is to forcibly kill the process. Using system() instead of popen() works okay. Can someone please investigate? Thanks!
You cannot use any non-async safe function in a signal handler. The small list of functions which is allowed is listed in section 2.4.3 of the XSH volume of POSIX.