On Tue, Apr 02 2019, Yufen Yu wrote:
> When doing re-add, we need to ensure rdev->mddev->pers is not NULL,
> which can avoid potential NULL pointer derefence in fallowing
> add_bound_rdev().
>
> Fixes: a6da4ef85cef ("md: re-add a failed disk")
> Cc: Xiao Ni <xni@xxxxxxxxxx>
> Cc: NeilBrown <neilb@xxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Thanks,
NeilBrown
> ---
> drivers/md/md.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 875b29ba5926..66b6bdf9f364 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -2859,8 +2859,10 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
> err = 0;
> }
> } else if (cmd_match(buf, "re-add")) {
> - if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
> - rdev->saved_raid_disk >= 0) {
> + if (!rdev->mddev->pers)
> + err = -EINVAL;
> + else if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
> + rdev->saved_raid_disk >= 0) {
> /* clear_bit is performed _after_ all the devices
> * have their local Faulty bit cleared. If any writes
> * happen in the meantime in the local node, they
> --
> 2.16.2.dirty
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