If /dev/binder is opened and the opener process then e.g. calls execve, proc->vma_vm_mm will still point to the location of the now-freed mm_struct. If the process then calls ioctl(binder_fd, ...), the dangling proc->vma_vm_mm pointer will be compared to current->mm. Let the binder take a reference to the mm_struct to avoid this. v2: use the right refcounter Fixes: a906d6931f3ccaf7de805643190765ddd7378e27 Signed-off-by: Jann Horn <jannh@xxxxxxxxxx> --- drivers/android/binder.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 16288e7..09fdb42 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2962,6 +2962,7 @@ static int binder_open(struct inode *nodp, struct file *filp) return -ENOMEM; get_task_struct(current); proc->tsk = current; + atomic_inc(¤t->mm->mm_count); proc->vma_vm_mm = current->mm; INIT_LIST_HEAD(&proc->todo); init_waitqueue_head(&proc->wait); @@ -3167,6 +3168,7 @@ static void binder_deferred_release(struct binder_proc *proc) vfree(proc->buffer); } + mmdrop(proc->vma_vm_mm); put_task_struct(proc->tsk); binder_debug(BINDER_DEBUG_OPEN_CLOSE, -- 2.8.0.rc3.226.g39d4020 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
