Commit 7ad6ef91 authored by Tuo Li's avatar Tuo Li Committed by Yu Kuai
Browse files

md/raid5: fix possible null-pointer dereferences in raid5_store_group_thread_cnt() 



The variable mddev->private is first assigned to conf and then checked:

  conf = mddev->private;
  if (!conf) ...

If conf is NULL, then mddev->private is also NULL. In this case,
null-pointer dereferences can occur when calling raid5_quiesce():

  raid5_quiesce(mddev, true);
  raid5_quiesce(mddev, false);

since mddev->private is assigned to conf again in raid5_quiesce(), and conf
is dereferenced in several places, for example:

  conf->quiesce = 0;
  wake_up(&conf->wait_for_quiescent);

To fix this issue, the function should unlock mddev and return before
invoking raid5_quiesce() when conf is NULL, following the existing pattern
in raid5_change_consistency_policy().

Fixes: fa1944bb ("md/raid5: Wait sync io to finish before changing group cnt")
Signed-off-by: default avatarTuo Li <islituo@gmail.com>
Reviewed-by: default avatarXiao Ni <xni@redhat.com>
Reviewed-by: default avatarPaul Menzel <pmenzel@molgen.mpg.de>
Link: https://lore.kernel.org/linux-raid/20251225130326.67780-1-islituo@gmail.com


Signed-off-by: default avatarYu Kuai <yukuai@fnnas.com>
parent 00f6c1b4

drivers/md/raid5.c

+6 −4
Original line number Diff line number Diff line
@@ -7187,12 +7187,14 @@ raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len) 
	err = mddev_suspend_and_lock(mddev);

	if (err)

		return err;

	conf = mddev->private;

	if (!conf) {

		mddev_unlock_and_resume(mddev);

		return -ENODEV;

	}

	raid5_quiesce(mddev, true);



	conf = mddev->private;

	if (!conf)

		err = -ENODEV;

	else if (new != conf->worker_cnt_per_group) {

	if (new != conf->worker_cnt_per_group) {

		old_groups = conf->worker_groups;

		if (old_groups)

			flush_workqueue(raid5_wq);