On 8/11/19 7:06 PM, 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 | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 11e64b5..620771d 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)
@@ -575,6 +580,7 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
struct scsi_device *sdev = cmd->device;
struct request_queue *q = sdev->request_queue;
+ bool ret;
if (blk_update_request(req, error, bytes))
return true;
@@ -613,12 +619,15 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
__blk_mq_end_request(req, error);
if (scsi_target(sdev)->single_lun ||
- !list_empty(&sdev->host->starved_list))
- kblockd_schedule_work(&sdev->requeue_work);
- else
+ !list_empty(&sdev->host->starved_list)) {
+ ret = kblockd_schedule_work(&sdev->requeue_work);
+ if (!ret)
+ percpu_ref_put(&q->q_usage_counter);
+ } else {
blk_mq_run_hw_queues(q, true);
+ percpu_ref_put(&q->q_usage_counter);
+ }
- percpu_ref_put(&q->q_usage_counter);
return false;
}
Is the new 'bool ret' variable really necessary?
Additionally, have you taken a look at the
cancel_work_sync(&sdev->requeue_work) call in __scsi_remove_device()?
Shouldn't the queue refcount be dropped if that cancel call cancels
queued work?
Thanks,
Bart.
