Re: [PATCH v2] md: add mddev->pers to avoid potential NULL pointer dereference

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@redhat.com Cc: NeilBrown neilb@suse.com Cc: stable@vger.kernel.org Signed-off-by: Yufen Yu yuyufen@huawei.com

Reviewed-by: NeilBrown neilb@suse.com

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