1 files changed, 25 insertions, 2 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 051f090d40c1..e2cd3e2a5ae8 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -66,6 +66,7 @@
 #include <linux/user-return-notifier.h>
 #include <linux/oom.h>
 #include <linux/khugepaged.h>
+#include <linux/signalfd.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -647,6 +648,26 @@ struct mm_struct *get_task_mm(struct task_struct *task)
 }
 EXPORT_SYMBOL_GPL(get_task_mm);
 
+struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
+{
+        struct mm_struct *mm;
+        int err;
+
+        err =  mutex_lock_killable(&task->signal->cred_guard_mutex);
+        if (err)
+                return ERR_PTR(err);
+
+        mm = get_task_mm(task);
+        if (mm && mm != current->mm &&
+                        !ptrace_may_access(task, mode)) {
+                mmput(mm);
+                mm = ERR_PTR(-EACCES);
+        }
+        mutex_unlock(&task->signal->cred_guard_mutex);
+
+        return mm;
+}
+
 /* Please note the differences between mmput and mm_release.
  * mmput is called whenever we stop holding onto a mm_struct,
  * error success whatever.
@@ -890,7 +911,7 @@ static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
                         return -ENOMEM;
 
                 new_ioc->ioprio = ioc->ioprio;
-                put_io_context(new_ioc, NULL);
+                put_io_context(new_ioc);
         }
 #endif
         return 0;
@@ -915,8 +936,10 @@ static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
 
 void __cleanup_sighand(struct sighand_struct *sighand)
 {
-        if (atomic_dec_and_test(&sighand->count))
+        if (atomic_dec_and_test(&sighand->count)) {
+                signalfd_cleanup(sighand);
                 kmem_cache_free(sighand_cachep, sighand);
+        }
 }