From: Tuo Li Date: Thu, 25 Dec 2025 13:03:26 +0000 (+0800) Subject: md/raid5: fix possible null-pointer dereferences in raid5_store_group_thread_cnt() X-Git-Tag: v6.19-rc4~8^2~1^2~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7ad6ef91d8745d04aff9cce7bdbc6320d8e05fe9;p=thirdparty%2Flinux.git 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: fa1944bbe622 ("md/raid5: Wait sync io to finish before changing group cnt") Signed-off-by: Tuo Li Reviewed-by: Xiao Ni Reviewed-by: Paul Menzel Link: https://lore.kernel.org/linux-raid/20251225130326.67780-1-islituo@gmail.com Signed-off-by: Yu Kuai --- diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index e57ce3295292..8dc98f545969 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -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);