1 files changed, 11 insertions, 5 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index fbea12d7a943..b373322ca497 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -108,8 +108,10 @@ void free_task(struct task_struct *tsk)
 }
 EXPORT_SYMBOL(free_task);
 
-void __put_task_struct(struct task_struct *tsk)
+void __put_task_struct_cb(struct rcu_head *rhp)
 {
+        struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
+
         WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
         WARN_ON(atomic_read(&tsk->usage));
         WARN_ON(tsk == current);
@@ -1060,6 +1062,12 @@ static task_t *copy_process(unsigned long clone_flags,
         p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
 
         /*
+         * sigaltstack should be cleared when sharing the same VM
+         */
+        if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
+                p->sas_ss_sp = p->sas_ss_size = 0;
+
+        /*
          * Syscall tracing should be turned off in the child regardless
          * of CLONE_PTRACE.
          */
@@ -1470,9 +1478,7 @@ static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
 
         if ((unshare_flags & CLONE_VM) &&
             (mm && atomic_read(&mm->mm_users) > 1)) {
-                *new_mmp = dup_mm(current);
-                if (!*new_mmp)
-                        return -ENOMEM;
+                return -EINVAL;
         }
 
         return 0;
@@ -1561,7 +1567,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
 
                 if (new_sigh) {
                         sigh = current->sighand;
-                        current->sighand = new_sigh;
+                        rcu_assign_pointer(current->sighand, new_sigh);
                         new_sigh = sigh;
                 }