mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-08 06:10:06 +00:00
d40ac01cbb
The recursive lock used on abort does not synchronize with a new process creation (either by fork-like interfaces or posix_spawn ones), nor it is reinitialized after fork(). Also, the SIGABRT unblock before raise() shows another race condition, where a fork or posix_spawn() call by another thread, just after the recursive lock release and before the SIGABRT signal, might create programs with a non-expected signal mask. With the default option (without POSIX_SPAWN_SETSIGDEF), the process can see SIG_DFL for SIGABRT, where it should be SIG_IGN. To fix the AS-safe, raise() does not change the process signal mask, and an AS-safe lock is used if a SIGABRT is installed or the process is blocked or ignored. With the signal mask change removal, there is no need to use a recursive loc. The lock is also taken on both _Fork() and posix_spawn(), to avoid the spawn process to see the abort handler as SIG_DFL. A read-write lock is used to avoid serialize _Fork and posix_spawn execution. Both sigaction (SIGABRT) and abort() requires to lock as writer (since both change the disposition). The fallback is also simplified: there is no need to use a loop of ABORT_INSTRUCTION after _exit() (if the syscall does not terminate the process, the system is broken). The proposed fix changes how setjmp works on a SIGABRT handler, where glibc does not save the signal mask. So usage like the below will now always abort. static volatile int chk_fail_ok; static jmp_buf chk_fail_buf; static void handler (int sig) { if (chk_fail_ok) { chk_fail_ok = 0; longjmp (chk_fail_buf, 1); } else _exit (127); } [...] signal (SIGABRT, handler); [....] chk_fail_ok = 1; if (! setjmp (chk_fail_buf)) { // Something that can calls abort, like a failed fortify function. chk_fail_ok = 0; printf ("FAIL\n"); } Such cases will need to use sigsetjmp instead. The _dl_start_profile calls sigaction through _profil, and to avoid pulling abort() on loader the call is replaced with __libc_sigaction. Checked on x86_64-linux-gnu and aarch64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com> |
||
---|---|---|
.. | ||
bits | ||
sys | ||
_Fork.c | ||
aio_misc.h | ||
cancellation-pc-check.h | ||
dl-mutex.c | ||
dl-thread_gscope_wait.c | ||
dl-tls_init_tp.c | ||
dl-tunables.list | ||
fork.h | ||
futex-internal.h | ||
gai_misc.h | ||
Implies | ||
internaltypes.h | ||
jmp-unwind.c | ||
libc_start_call_main.h | ||
libc-lock.h | ||
libc-lockP.h | ||
lowlevellock-futex.h | ||
lowlevellock.h | ||
Makeconfig | ||
Makefile | ||
malloc-machine.h | ||
proc_service.h | ||
pthread_atfork_compat.h | ||
pthread_early_init.h | ||
pthread_mutex_backoff.h | ||
pthread_mutex_conf.h | ||
pthread-offsets.h | ||
pthread.h | ||
pthreadP.h | ||
setxid.h | ||
stdio-lock.h | ||
Subdirs | ||
tcb-access.h | ||
tcb-offsets.h | ||
thread_db.h | ||
thread_pointer.h | ||
timer_routines.h | ||
tst-mqueue8x.c |