[PATCH AUTOSEL 5.4 3/4] md: raid1: fix potential OOB in raid1_remove_disk()

[Sasha Levin <sashal@kernel.org>]

From: Zhang Shurong <zhang_shurong@foxmail.com>

[ Upstream commit 8b0472b50bcf0f19a5119b00a53b63579c8e1e4d ]

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 <zhang_shurong@foxmail.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/tencent_0D24426FAC6A21B69AC0C03CE4143A508F09@qq.com
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/raid1.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 1919de4c8c12d..f96e079454700 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1808,6 +1808,10 @@ 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)
-- 
2.40.1