Firstly during CPU hotplug, even queue is freezed, timeout handler still may come and access hctx->tags, which may cause use after free, so this patch deactivates timeout handler inside CPU hotplug notifier.
Secondly, tags can be shared by more than one queues, so we have to check if the hctx has been unmapped, otherwise still use-after-free on tags can be triggered. Cc: <[email protected]> Reported-by: Dongsu Park <[email protected]> Tested-by: Dongsu Park <[email protected]> Signed-off-by: Ming Lei <[email protected]> --- block/blk-mq.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index ade8a2d..1fccb98 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -677,8 +677,11 @@ static void blk_mq_rq_timer(unsigned long priv) data.next = blk_rq_timeout(round_jiffies_up(data.next)); mod_timer(&q->timeout, data.next); } else { - queue_for_each_hw_ctx(q, hctx, i) - blk_mq_tag_idle(hctx); + queue_for_each_hw_ctx(q, hctx, i) { + /* the hctx may be unmapped, so check it here */ + if (blk_mq_hw_queue_mapped(hctx)) + blk_mq_tag_idle(hctx); + } } } @@ -2090,9 +2093,16 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb, */ list_for_each_entry(q, &all_q_list, all_q_node) blk_mq_freeze_queue_start(q); - list_for_each_entry(q, &all_q_list, all_q_node) + list_for_each_entry(q, &all_q_list, all_q_node) { blk_mq_freeze_queue_wait(q); + /* + * timeout handler can't touch hw queue during the + * reinitialization + */ + del_timer_sync(&q->timeout); + } + list_for_each_entry(q, &all_q_list, all_q_node) blk_mq_queue_reinit(q); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
