android: binder: Sanity check at binder ioctl

Sanity check at binder ioctl function,
Only allow the shared mm_struct to use the same binder-object
to do binder operate.

And add proc->vma_vm_mm = current->mm at the open function.
The libbinder do ioctl before mmap called.

V2: Fix compile error for error commit
V3: Change the condition to proc->vma_vm_mm

Signed-off-by: Chen Feng <[email protected]>
Signed-off-by: Wei  Dong <[email protected]>
Signed-off-by: Junmin Zhao <[email protected]>
Reviewed-by: Zhuangluan Su <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/android/binder.c

@@ -2737,6 +2737,10 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	/*pr_info("binder_ioctl: %d:%d %x %lx\n",
 			proc->pid, current->pid, cmd, arg);*/
 
+	if (unlikely(current->mm != proc->vma_vm_mm)) {
+		pr_err("current mm mismatch proc mm\n");
+		return -EINVAL;
+	}
 	trace_binder_ioctl(cmd, arg);
 
 	ret = wait_event_interruptible(binder_user_error_wait, binder_stop_on_user_error < 2);
@@ -2951,6 +2955,7 @@ static int binder_open(struct inode *nodp, struct file *filp)
 		return -ENOMEM;
 	get_task_struct(current);
 	proc->tsk = current;
+	proc->vma_vm_mm = current->mm;
 	INIT_LIST_HEAD(&proc->todo);
 	init_waitqueue_head(&proc->wait);
 	proc->default_priority = task_nice(current);