From: Christoph Böhmwalder christoph.boehmwalder@linbit.com
[ Upstream commit 6d42ddf7f27b6723549ee6d4c8b1b418b59bf6b5 ]
Commit c347a787e34cb (drbd: set ->bi_bdev in drbd_req_new) moved a bio_set_dev call (which has since been removed) to "earlier", from drbd_request_prepare to drbd_req_new.
The problem is that this accesses device->ldev->backing_bdev, which is not NULL-checked at this point. When we don't have an ldev (i.e. when the DRBD device is diskless), this leads to a null pointer deref.
So, only allocate the private_bio if we actually have a disk. This is also a small optimization, since we don't clone the bio to only to immediately free it again in the diskless case.
Fixes: c347a787e34cb ("drbd: set ->bi_bdev in drbd_req_new") Co-developed-by: Christoph Böhmwalder christoph.boehmwalder@linbit.com Signed-off-by: Christoph Böhmwalder christoph.boehmwalder@linbit.com Co-developed-by: Joel Colledge joel.colledge@linbit.com Signed-off-by: Joel Colledge joel.colledge@linbit.com Reviewed-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20221020085205.129090-1-christoph.boehmwalder@linb... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/drbd/drbd_req.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 8f7f144e54f3..7f9bcc82fc9c 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -30,11 +30,6 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio return NULL; memset(req, 0, sizeof(*req));
- req->private_bio = bio_alloc_clone(device->ldev->backing_bdev, bio_src, - GFP_NOIO, &drbd_io_bio_set); - req->private_bio->bi_private = req; - req->private_bio->bi_end_io = drbd_request_endio; - req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0) | (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_ZEROES : 0) | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0); @@ -1219,9 +1214,12 @@ drbd_request_prepare(struct drbd_device *device, struct bio *bio) /* Update disk stats */ req->start_jif = bio_start_io_acct(req->master_bio);
- if (!get_ldev(device)) { - bio_put(req->private_bio); - req->private_bio = NULL; + if (get_ldev(device)) { + req->private_bio = bio_alloc_clone(device->ldev->backing_bdev, + bio, GFP_NOIO, + &drbd_io_bio_set); + req->private_bio->bi_private = req; + req->private_bio->bi_end_io = drbd_request_endio; }
/* process discards always from our submitter thread */