When a process fork a child process, we should not allow the child process use the binder which opened by parent process.
But if the binder-object creater is a thread of one process who exit, the other thread can also use this binder-object normally. We can distinguish this by the member proc->tsk->mm. If the thread exit the tsk->mm will be NULL.
proc->tsk->mm != current->mm && proc->tsk->mm
So only allow the shared mm_struct to use the same binder-object and check the existence of mm_struct.
Signed-off-by: Chen Feng email@example.com Signed-off-by: Wei Dong firstname.lastname@example.org Signed-off-by: Junmin Zhao email@example.com Reviewed-by: Zhuangluan Su firstname.lastname@example.org --- drivers/android/binder.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index a39e85f..279063c 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2736,6 +2736,8 @@ 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(proc->tsk->mm != current->mm && proc->tsk->mm)) + return -EINVAL;