[PATCH] md/raid1: Fix use-after-free in reshape pool wait queue

[Wang Jinchao]

During raid1 reshape operations, a use-after-free can occur in the mempool
wait queue when r1bio_pool->curr_nr drops below min_nr. This happens
because:

1. mempool_init() initializes wait queue head on stack
2. The stack-allocated wait queue is copied to conf->r1bio_pool through
   structure assignment
3. wake_up() on this invalid wait queue causes panic when accessing the
   stack memory that no longer exists

Fix this by properly reinitializing the mempool's wait queue using
init_waitqueue_head(), ensuring the wait queue structure remains valid
throughout the reshape operation.

Signed-off-by: Wang Jinchao <wangjinchao600@xxxxxxxxx>
---
 drivers/md/raid1.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 19c5a0ce5a40..fd4ce2a4136f 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3428,6 +3428,7 @@ static int raid1_reshape(struct mddev *mddev)
 	/* ok, everything is stopped */
 	oldpool = conf->r1bio_pool;
 	conf->r1bio_pool = newpool;
+	init_waitqueue_head(&conf->r1bio_pool.wait);
 
 	for (d = d2 = 0; d < conf->raid_disks; d++) {
 		struct md_rdev *rdev = conf->mirrors[d].rdev;
-- 
2.43.0