If rddev->raid_disk is greater than mddev->raid_disks, there will be
an out-of-bounds in raid1_remove_disk(). We have already found
similar reports as follows:

1) commit d17f744e883b ("md-raid10: fix KASAN warning")
2) commit 1ebc2cec0b7d ("dm raid: fix KASAN warning in raid5_remove_disk")

Fix this bug by checking whether the "number" variable is
valid.

Signed-off-by: Zhang Shurong <redacted>
---
  drivers/md/raid1.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index dd25832eb045..3e294dc408fa 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c

@@ -1829,6 +1829,10 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
  	struct r1conf *conf = mddev->private;
  	int err = 0;
  	int number = rdev->raid_disk;
+
+	if (unlikely(number >= mddev->raid_disks))
+		goto abort;
+