This is a note to let you know that I've just added the patch titled ublk_drv: don't probe partitions if the ubq daemon isn't trusted to the 6.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ublk_drv-don-t-probe-partitions-if-the-ubq-daemon-is.patch and it can be found in the queue-6.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 14bed80b0952fcd246140005b3b736f6f9beff32 Author: Ming Lei <ming.lei@xxxxxxxxxx> Date: Fri Jan 6 12:17:07 2023 +0800 ublk_drv: don't probe partitions if the ubq daemon isn't trusted [ Upstream commit 73a166d9749230d598320fdae3b687cdc0e2e205 ] If any ubq daemon is unprivileged, the ublk char device is allowed for unprivileged user actually, and we can't trust the current user, so not probe partitions. Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver") Reviewed-by: ZiyangZhang <ZiyangZhang@xxxxxxxxxxxxxxxxx> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230106041711.914434-3-ming.lei@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index f44b9467720c9..450bd54fd0061 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -159,6 +159,7 @@ struct ublk_device { struct completion completion; unsigned int nr_queues_ready; + unsigned int nr_privileged_daemon; /* * Our ubq->daemon may be killed without any notification, so @@ -1178,6 +1179,9 @@ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq) ubq->ubq_daemon = current; get_task_struct(ubq->ubq_daemon); ub->nr_queues_ready++; + + if (capable(CAP_SYS_ADMIN)) + ub->nr_privileged_daemon++; } if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues) complete_all(&ub->completion); @@ -1534,6 +1538,10 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd) if (ret) goto out_put_disk; + /* don't probe partitions if any one ubq daemon is un-trusted */ + if (ub->nr_privileged_daemon != ub->nr_queues_ready) + set_bit(GD_SUPPRESS_PART_SCAN, &disk->state); + get_device(&ub->cdev_dev); ret = add_disk(disk); if (ret) { @@ -1935,6 +1943,7 @@ static int ublk_ctrl_start_recovery(struct io_uring_cmd *cmd) /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */ ub->mm = NULL; ub->nr_queues_ready = 0; + ub->nr_privileged_daemon = 0; init_completion(&ub->completion); ret = 0; out_unlock: