signals: don't abuse __flush_signals() in selinux_bprm_committed_creds()
selinux_bprm_committed_creds()->__flush_signals() is not right, we
shouldn't clear TIF_SIGPENDING unconditionally. There can be other
reasons for signal_pending(): freezing(), JOBCTL_PENDING_MASK, and
potentially more.
Also change this code to check fatal_signal_pending() rather than
SIGNAL_GROUP_EXIT, it looks a bit better.
Now we can kill __flush_signals() before it finds another buggy user.
Note: this code looks racy, we can flush a signal which was sent after
the task SID has been updated.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8222ae4..4f84aad 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2373,7 +2373,6 @@
extern void proc_caches_init(void);
extern void flush_signals(struct task_struct *);
-extern void __flush_signals(struct task_struct *);
extern void ignore_signals(struct task_struct *);
extern void flush_signal_handlers(struct task_struct *, int force_default);
extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
diff --git a/kernel/signal.c b/kernel/signal.c
index d51c5dd..d497250 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -414,21 +414,16 @@
}
/*
- * Flush all pending signals for a task.
+ * Flush all pending signals for this kthread.
*/
-void __flush_signals(struct task_struct *t)
-{
- clear_tsk_thread_flag(t, TIF_SIGPENDING);
- flush_sigqueue(&t->pending);
- flush_sigqueue(&t->signal->shared_pending);
-}
-
void flush_signals(struct task_struct *t)
{
unsigned long flags;
spin_lock_irqsave(&t->sighand->siglock, flags);
- __flush_signals(t);
+ clear_tsk_thread_flag(t, TIF_SIGPENDING);
+ flush_sigqueue(&t->pending);
+ flush_sigqueue(&t->signal->shared_pending);
spin_unlock_irqrestore(&t->sighand->siglock, flags);
}
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 99c4a00..8abbd54 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2416,10 +2416,12 @@
for (i = 0; i < 3; i++)
do_setitimer(i, &itimer, NULL);
spin_lock_irq(¤t->sighand->siglock);
- if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
- __flush_signals(current);
+ if (!fatal_signal_pending(current)) {
+ flush_sigqueue(¤t->pending);
+ flush_sigqueue(¤t->signal->shared_pending);
flush_signal_handlers(current, 1);
sigemptyset(¤t->blocked);
+ recalc_sigpending();
}
spin_unlock_irq(¤t->sighand->siglock);
}