diff options
| -rw-r--r-- | src/exit/abort.c | 19 | ||||
| -rw-r--r-- | src/signal/sigaction.c | 25 |
2 files changed, 40 insertions, 4 deletions
diff --git a/src/exit/abort.c b/src/exit/abort.c index ecc0f735..d6bd546b 100644 --- a/src/exit/abort.c +++ b/src/exit/abort.c @@ -3,11 +3,30 @@ #include "syscall.h" #include "pthread_impl.h" #include "atomic.h" +#include "libc.h" +#include "ksigaction.h" + +__attribute__((__visibility__("hidden"))) +volatile int __abort_lock[1]; _Noreturn void abort(void) { raise(SIGABRT); + + /* If there was a SIGABRT handler installed and it returned, or if + * SIGABRT was blocked or ignored, take an AS-safe lock to prevent + * sigaction from installing a new SIGABRT handler, uninstall any + * handler that may be present, and re-raise the signal to generate + * the default action of abnormal termination. */ __block_all_sigs(0); + LOCK(__abort_lock); + __syscall(SYS_rt_sigaction, SIGABRT, + &(struct k_sigaction){.handler = SIG_DFL}, 0, _NSIG/8); + __syscall(SYS_tkill, __pthread_self()->tid, SIGABRT); + __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, + &(long[_NSIG/(8*sizeof(long))]){1UL<<(SIGABRT-1)}, 0, _NSIG/8); + + /* Beyond this point should be unreachable. */ a_crash(); raise(SIGKILL); _Exit(127); diff --git a/src/signal/sigaction.c b/src/signal/sigaction.c index 6eca06f1..79989500 100644 --- a/src/signal/sigaction.c +++ b/src/signal/sigaction.c @@ -6,6 +6,11 @@ #include "libc.h" #include "ksigaction.h" +volatile int dummy_lock[1] = { 0 }; + +__attribute__((__visibility__("hidden"))) +weak_alias(dummy_lock, __abort_lock); + static int unmask_done; static unsigned long handler_set[_NSIG/(8*sizeof(long))]; @@ -17,6 +22,7 @@ void __get_handler_set(sigset_t *set) int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old) { struct k_sigaction ksa, ksa_old; + unsigned long set[_NSIG/(8*sizeof(long))]; if (sa) { if ((uintptr_t)sa->sa_handler > 1UL) { a_or_l(handler_set+(sig-1)/(8*sizeof(long)), @@ -36,19 +42,30 @@ int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigact unmask_done = 1; } } + /* Changing the disposition of SIGABRT to anything but + * SIG_DFL requires a lock, so that it cannot be changed + * while abort is terminating the process after simply + * calling raise(SIGABRT) failed to do so. */ + if (sa->sa_handler != SIG_DFL && sig == SIGABRT) { + __block_all_sigs(&set); + LOCK(__abort_lock); + } ksa.handler = sa->sa_handler; ksa.flags = sa->sa_flags | SA_RESTORER; ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore; memcpy(&ksa.mask, &sa->sa_mask, sizeof ksa.mask); } - if (syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, sizeof ksa.mask)) - return -1; - if (old) { + int r = __syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, sizeof ksa.mask); + if (sig == SIGABRT && sa && sa->sa_handler != SIG_DFL) { + UNLOCK(__abort_lock); + __restore_sigs(&set); + } + if (old && !r) { old->sa_handler = ksa_old.handler; old->sa_flags = ksa_old.flags; memcpy(&old->sa_mask, &ksa_old.mask, sizeof ksa_old.mask); } - return 0; + return __syscall_ret(r); } int __sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old) |