md: raid1: fix potential OOB in raid1_remove_disk()

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 d17f744 ("md-raid10: fix KASAN warning")
2) commit 1ebc2ce ("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 <[email protected]>
Reviewed-by: Yu Kuai <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Song Liu <[email protected]>

Author: ZhangShurong

drivers/md/raid1.c

@@ -1837,6 +1837,10 @@ 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 >= conf->raid_disks))
+		goto abort;
+
 	struct raid1_info *p = conf->mirrors + number;
 
 	if (rdev != p->rdev)