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Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c116
1 files changed, 98 insertions, 18 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index f3f1f7a972fd..96e8c3cbfa38 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -72,7 +72,7 @@ static int sig_task_ignored(struct task_struct *t, int sig, bool force)
handler = sig_handler(t, sig);
if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
- handler == SIG_DFL && !force)
+ handler == SIG_DFL && !(force && sig_kernel_only(sig)))
return 1;
return sig_handler_ignored(handler, sig);
@@ -88,13 +88,15 @@ static int sig_ignored(struct task_struct *t, int sig, bool force)
if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
return 0;
- if (!sig_task_ignored(t, sig, force))
- return 0;
-
/*
- * Tracers may want to know about even ignored signals.
+ * Tracers may want to know about even ignored signal unless it
+ * is SIGKILL which can't be reported anyway but can be ignored
+ * by SIGNAL_UNKILLABLE task.
*/
- return !t->ptrace;
+ if (t->ptrace && sig != SIGKILL)
+ return 0;
+
+ return sig_task_ignored(t, sig, force);
}
/*
@@ -346,7 +348,7 @@ static bool task_participate_group_stop(struct task_struct *task)
* fresh group stop. Read comment in do_signal_stop() for details.
*/
if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
- sig->flags = SIGNAL_STOP_STOPPED;
+ signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
return true;
}
return false;
@@ -503,7 +505,8 @@ int unhandled_signal(struct task_struct *tsk, int sig)
return !tsk->ptrace;
}
-static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
+static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
+ bool *resched_timer)
{
struct sigqueue *q, *first = NULL;
@@ -525,6 +528,12 @@ static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
still_pending:
list_del_init(&first->list);
copy_siginfo(info, &first->info);
+
+ *resched_timer =
+ (first->flags & SIGQUEUE_PREALLOC) &&
+ (info->si_code == SI_TIMER) &&
+ (info->si_sys_private);
+
__sigqueue_free(first);
} else {
/*
@@ -541,12 +550,12 @@ still_pending:
}
static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
- siginfo_t *info)
+ siginfo_t *info, bool *resched_timer)
{
int sig = next_signal(pending, mask);
if (sig)
- collect_signal(sig, pending, info);
+ collect_signal(sig, pending, info, resched_timer);
return sig;
}
@@ -558,15 +567,16 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
*/
int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
{
+ bool resched_timer = false;
int signr;
/* We only dequeue private signals from ourselves, we don't let
* signalfd steal them
*/
- signr = __dequeue_signal(&tsk->pending, mask, info);
+ signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
if (!signr) {
signr = __dequeue_signal(&tsk->signal->shared_pending,
- mask, info);
+ mask, info, &resched_timer);
/*
* itimer signal ?
*
@@ -611,7 +621,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
*/
current->jobctl |= JOBCTL_STOP_DEQUEUED;
}
- if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
+ if (resched_timer) {
/*
* Release the siglock to ensure proper locking order
* of timer locks outside of siglocks. Note, we leave
@@ -686,6 +696,48 @@ static inline bool si_fromuser(const struct siginfo *info)
(!is_si_special(info) && SI_FROMUSER(info));
}
+static int dequeue_synchronous_signal(siginfo_t *info)
+{
+ struct task_struct *tsk = current;
+ struct sigpending *pending = &tsk->pending;
+ struct sigqueue *q, *sync = NULL;
+
+ /*
+ * Might a synchronous signal be in the queue?
+ */
+ if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
+ return 0;
+
+ /*
+ * Return the first synchronous signal in the queue.
+ */
+ list_for_each_entry(q, &pending->list, list) {
+ /* Synchronous signals have a postive si_code */
+ if ((q->info.si_code > SI_USER) &&
+ (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
+ sync = q;
+ goto next;
+ }
+ }
+ return 0;
+next:
+ /*
+ * Check if there is another siginfo for the same signal.
+ */
+ list_for_each_entry_continue(q, &pending->list, list) {
+ if (q->info.si_signo == sync->info.si_signo)
+ goto still_pending;
+ }
+
+ sigdelset(&pending->signal, sync->info.si_signo);
+ recalc_sigpending();
+still_pending:
+ list_del_init(&sync->list);
+ copy_siginfo(info, &sync->info);
+ __sigqueue_free(sync);
+ return info->si_signo;
+}
+
/*
* called with RCU read lock from check_kill_permission()
*/
@@ -837,7 +889,7 @@ static bool prepare_signal(int sig, struct task_struct *p, bool force)
* will take ->siglock, notice SIGNAL_CLD_MASK, and
* notify its parent. See get_signal_to_deliver().
*/
- signal->flags = why | SIGNAL_STOP_CONTINUED;
+ signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
signal->group_stop_count = 0;
signal->group_exit_code = 0;
}
@@ -909,9 +961,9 @@ static void complete_signal(int sig, struct task_struct *p, int group)
* then start taking the whole group down immediately.
*/
if (sig_fatal(p, sig) &&
- !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
+ !(signal->flags & SIGNAL_GROUP_EXIT) &&
!sigismember(&t->real_blocked, sig) &&
- (sig == SIGKILL || !t->ptrace)) {
+ (sig == SIGKILL || !p->ptrace)) {
/*
* This signal will be fatal to the whole group.
*/
@@ -981,7 +1033,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
result = TRACE_SIGNAL_IGNORED;
if (!prepare_signal(sig, t,
- from_ancestor_ns || (info == SEND_SIG_FORCED)))
+ from_ancestor_ns || (info == SEND_SIG_PRIV) || (info == SEND_SIG_FORCED)))
goto ret;
pending = group ? &t->signal->shared_pending : &t->pending;
@@ -1382,6 +1434,10 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
return ret;
}
+ /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
+ if (pid == INT_MIN)
+ return -ESRCH;
+
read_lock(&tasklist_lock);
if (pid != -1) {
ret = __kill_pgrp_info(sig, info,
@@ -2184,6 +2240,14 @@ relock:
goto relock;
}
+ /* Has this task already been marked for death? */
+ if (signal_group_exit(signal)) {
+ ksig->info.si_signo = signr = SIGKILL;
+ sigdelset(&current->pending.signal, SIGKILL);
+ recalc_sigpending();
+ goto fatal;
+ }
+
for (;;) {
struct k_sigaction *ka;
@@ -2197,7 +2261,15 @@ relock:
goto relock;
}
- signr = dequeue_signal(current, &current->blocked, &ksig->info);
+ /*
+ * Signals generated by the execution of an instruction
+ * need to be delivered before any other pending signals
+ * so that the instruction pointer in the signal stack
+ * frame points to the faulting instruction.
+ */
+ signr = dequeue_synchronous_signal(&ksig->info);
+ if (!signr)
+ signr = dequeue_signal(current, &current->blocked, &ksig->info);
if (!signr)
break; /* will return 0 */
@@ -2279,6 +2351,7 @@ relock:
continue;
}
+ fatal:
spin_unlock_irq(&sighand->siglock);
/*
@@ -2485,6 +2558,13 @@ void __set_current_blocked(const sigset_t *newset)
{
struct task_struct *tsk = current;
+ /*
+ * In case the signal mask hasn't changed, there is nothing we need
+ * to do. The current->blocked shouldn't be modified by other task.
+ */
+ if (sigequalsets(&tsk->blocked, newset))
+ return;
+
spin_lock_irq(&tsk->sighand->siglock);
__set_task_blocked(tsk, newset);
spin_unlock_irq(&tsk->sighand->siglock);