On Mon, Sep 11, 2023 at 2:49 AM Pavel Machek [off-list ref] wrote:

Hi!

quoted

From: Zhang Shurong <redacted>

[ 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.

quoted

+++ b/drivers/md/raid1.c

@@ -1775,6 +1775,10 @@ 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)

Wow. Mixing declarations and code. I'm pretty sure that's not ok
according to our coding style, and I'd be actually surprised if all
our compiler configurations allowed this.

We have a fix queued for this:

https://git.kernel.org/pub/scm/linux/kernel/git/song/md.git/commit/?h=md-fixes&id=df203da47f4428bc286fc99318936416253a321c

Thanks,
Song