On 8/9/19 2:03 AM, zhengbin wrote:
> KASAN reports a use-after-free in 4.19-stable,
> which won't happen after commit 47cdee29ef9d
> ("block: move blk_exit_queue into __blk_release_queue").
> However, backport this patch to 4.19-stable will be a lot of work and
> the risk is great. Moreover, we should make sure scsi_requeue_run_queue
> is done before blk_cleanup_queue in master too.
>
> BUG: KASAN: use-after-free in dd_has_work+0x50/0xe8
> Read of size 8 at addr ffff808b57c6f168 by task kworker/53:1H/6910
>
> CPU: 53 PID: 6910 Comm: kworker/53:1H Kdump: loaded Tainted: G
> Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.59 01/31/2019
> Workqueue: kblockd scsi_requeue_run_queue
> Call trace:
> dump_backtrace+0x0/0x270
> show_stack+0x24/0x30
> dump_stack+0xb4/0xe4
> print_address_description+0x68/0x278
> kasan_report+0x204/0x330
> __asan_load8+0x88/0xb0
> dd_has_work+0x50/0xe8
> blk_mq_run_hw_queue+0x19c/0x218
> blk_mq_run_hw_queues+0x7c/0xb0
> scsi_run_queue+0x3ec/0x520
> scsi_requeue_run_queue+0x2c/0x38
> process_one_work+0x2e4/0x6d8
> worker_thread+0x6c/0x6a8
> kthread+0x1b4/0x1c0
> ret_from_fork+0x10/0x18
>
> Allocated by task 46843:
> kasan_kmalloc+0xe0/0x190
> kmem_cache_alloc_node_trace+0x10c/0x258
> dd_init_queue+0x68/0x190
> blk_mq_init_sched+0x1cc/0x300
> elevator_init_mq+0x90/0xe0
> blk_mq_init_allocated_queue+0x700/0x728
> blk_mq_init_queue+0x48/0x90
> scsi_mq_alloc_queue+0x34/0xb0
> scsi_alloc_sdev+0x340/0x530
> scsi_probe_and_add_lun+0x46c/0x1260
> __scsi_scan_target+0x1b8/0x7b0
> scsi_scan_target+0x140/0x150
> fc_scsi_scan_rport+0x164/0x178 [scsi_transport_fc]
> process_one_work+0x2e4/0x6d8
> worker_thread+0x6c/0x6a8
> kthread+0x1b4/0x1c0
> ret_from_fork+0x10/0x18
>
> Freed by task 46843:
> __kasan_slab_free+0x120/0x228
> kasan_slab_free+0x10/0x18
> kfree+0x88/0x218
> dd_exit_queue+0x5c/0x78
> blk_mq_exit_sched+0x104/0x130
> elevator_exit+0xa8/0xc8
> blk_exit_queue+0x48/0x78
> blk_cleanup_queue+0x170/0x248
> __scsi_remove_device+0x84/0x1b0
> scsi_probe_and_add_lun+0xd00/0x1260
> __scsi_scan_target+0x1b8/0x7b0
> scsi_scan_target+0x140/0x150
> fc_scsi_scan_rport+0x164/0x178 [scsi_transport_fc]
> process_one_work+0x2e4/0x6d8
> worker_thread+0x6c/0x6a8
> kthread+0x1b4/0x1c0
> ret_from_fork+0x10/0x18
>
> Fixes: 8dc765d438f1 ("SCSI: fix queue cleanup race before queue initialization is done")
> Signed-off-by: zhengbin <zhengbin13@xxxxxxxxxx>
> ---
> drivers/scsi/scsi_lib.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 11e64b5..e5ef180 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -531,6 +531,11 @@ void scsi_requeue_run_queue(struct work_struct *work)
> sdev = container_of(work, struct scsi_device, requeue_work);
> q = sdev->request_queue;
> scsi_run_queue(q);
> + /*
> + * need to put q_usage_counter which
> + * is got in scsi_end_request.
> + */
> + percpu_ref_put(&q->q_usage_counter);
> }
>
> void scsi_run_host_queues(struct Scsi_Host *shost)
> @@ -615,10 +620,11 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
> if (scsi_target(sdev)->single_lun ||
> !list_empty(&sdev->host->starved_list))
> kblockd_schedule_work(&sdev->requeue_work);
> - else
> + else {
> blk_mq_run_hw_queues(q, true);
> + percpu_ref_put(&q->q_usage_counter);
> + }
>
> - percpu_ref_put(&q->q_usage_counter);
> return false;
> }
Can kblockd_schedule_work() return 0? If so, should percpu_ref_put() be
called in that case?
Bart.
