6.18-stable review patch. If anyone has any objections, please let me know.
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From: Yun Zhou yun.zhou@windriver.com
[ Upstream commit 0dc76205549b4c25705e54345f211b9f66e018a0 ]
We attempted to use RCU to protect the pointer 'thread', but directly passed the value when calling md_wakeup_thread(). This means that the RCU pointer has been acquired before rcu_read_lock(), which renders rcu_read_lock() ineffective and could lead to a use-after-free.
Link: https://lore.kernel.org/linux-raid/20251015083227.1079009-1-yun.zhou@windriv... Fixes: 446931543982 ("md: protect md_thread with rcu") Signed-off-by: Yun Zhou yun.zhou@windriver.com Reviewed-by: Li Nan linan122@huawei.com Reviewed-by: Yu Kuai yukuai@fnnas.com Signed-off-by: Yu Kuai yukuai@fnnas.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/md.c | 14 ++++++-------- drivers/md/md.h | 8 +++++++- 2 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c index 8128c8839a082..6062e0deb6160 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -99,7 +99,7 @@ static int remove_and_add_spares(struct mddev *mddev, struct md_rdev *this); static void mddev_detach(struct mddev *mddev); static void export_rdev(struct md_rdev *rdev, struct mddev *mddev); -static void md_wakeup_thread_directly(struct md_thread __rcu *thread); +static void md_wakeup_thread_directly(struct md_thread __rcu **thread);
/* * Default number of read corrections we'll attempt on an rdev @@ -5136,7 +5136,7 @@ static void stop_sync_thread(struct mddev *mddev, bool locked) * Thread might be blocked waiting for metadata update which will now * never happen */ - md_wakeup_thread_directly(mddev->sync_thread); + md_wakeup_thread_directly(&mddev->sync_thread); if (work_pending(&mddev->sync_work)) flush_work(&mddev->sync_work);
@@ -8375,22 +8375,21 @@ static int md_thread(void *arg) return 0; }
-static void md_wakeup_thread_directly(struct md_thread __rcu *thread) +static void md_wakeup_thread_directly(struct md_thread __rcu **thread) { struct md_thread *t;
rcu_read_lock(); - t = rcu_dereference(thread); + t = rcu_dereference(*thread); if (t) wake_up_process(t->tsk); rcu_read_unlock(); }
-void md_wakeup_thread(struct md_thread __rcu *thread) +void __md_wakeup_thread(struct md_thread __rcu *thread) { struct md_thread *t;
- rcu_read_lock(); t = rcu_dereference(thread); if (t) { pr_debug("md: waking up MD thread %s.\n", t->tsk->comm); @@ -8398,9 +8397,8 @@ void md_wakeup_thread(struct md_thread __rcu *thread) if (wq_has_sleeper(&t->wqueue)) wake_up(&t->wqueue); } - rcu_read_unlock(); } -EXPORT_SYMBOL(md_wakeup_thread); +EXPORT_SYMBOL(__md_wakeup_thread);
struct md_thread *md_register_thread(void (*run) (struct md_thread *), struct mddev *mddev, const char *name) diff --git a/drivers/md/md.h b/drivers/md/md.h index 1979c2d4fe89e..5d5f780b84477 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -882,6 +882,12 @@ struct md_io_clone {
#define THREAD_WAKEUP 0
+#define md_wakeup_thread(thread) do { \ + rcu_read_lock(); \ + __md_wakeup_thread(thread); \ + rcu_read_unlock(); \ +} while (0) + static inline void safe_put_page(struct page *p) { if (p) put_page(p); @@ -895,7 +901,7 @@ extern struct md_thread *md_register_thread( struct mddev *mddev, const char *name); extern void md_unregister_thread(struct mddev *mddev, struct md_thread __rcu **threadp); -extern void md_wakeup_thread(struct md_thread __rcu *thread); +extern void __md_wakeup_thread(struct md_thread __rcu *thread); extern void md_check_recovery(struct mddev *mddev); extern void md_reap_sync_thread(struct mddev *mddev); extern enum sync_action md_sync_action(struct mddev *mddev);