Merge branch 'core-signals-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cascardo/linux.git] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8db05e4..e8dfa6f 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1595,6 +1595,7 @@ struct task_struct {
 
        unsigned long sas_ss_sp;
        size_t sas_ss_size;
+       unsigned sas_ss_flags;
 
        struct callback_head *task_works;
 
@@ -2574,6 +2575,18 @@ static inline int kill_cad_pid(int sig, int priv)
  */
 static inline int on_sig_stack(unsigned long sp)
 {
+       /*
+        * If the signal stack is SS_AUTODISARM then, by construction, we
+        * can't be on the signal stack unless user code deliberately set
+        * SS_AUTODISARM when we were already on it.
+        *
+        * This improves reliability: if user state gets corrupted such that
+        * the stack pointer points very close to the end of the signal stack,
+        * then this check will enable the signal to be handled anyway.
+        */
+       if (current->sas_ss_flags & SS_AUTODISARM)
+               return 0;
+
 #ifdef CONFIG_STACK_GROWSUP
        return sp >= current->sas_ss_sp &&
                sp - current->sas_ss_sp < current->sas_ss_size;
@@ -2591,6 +2604,13 @@ static inline int sas_ss_flags(unsigned long sp)
        return on_sig_stack(sp) ? SS_ONSTACK : 0;
 }
 
+static inline void sas_ss_reset(struct task_struct *p)
+{
+       p->sas_ss_sp = 0;
+       p->sas_ss_size = 0;
+       p->sas_ss_flags = SS_DISABLE;
+}
+
 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
 {
        if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))