From 7e3497d7dacb5aee69dd9be842b778083cae0e75 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 27 Mar 2025 17:51:10 +0800 Subject: [PATCH] ublk: make sure ubq->canceling is set when queue is frozen [ Upstream commit 8741d0737921ec1c03cf59aebf4d01400c2b461a ] Now ublk driver depends on `ubq->canceling` for deciding if the request can be dispatched via uring_cmd & io_uring_cmd_complete_in_task(). Once ubq->canceling is set, the uring_cmd can be done via ublk_cancel_cmd() and io_uring_cmd_done(). So set ubq->canceling when queue is frozen, this way makes sure that the flag can be observed from ublk_queue_rq() reliably, and avoids use-after-free on uring_cmd. Fixes: 216c8f5ef0f2 ("ublk: replace monitor with cancelable uring_cmd") Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20250327095123.179113-2-ming.lei@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/ublk_drv.c | 41 +++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index c7d728d686e5..79b7bd8bfd45 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1416,18 +1416,28 @@ static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq) } } -static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) +/* Must be called when queue is frozen */ +static bool ublk_mark_queue_canceling(struct ublk_queue *ubq) { - struct gendisk *disk; + bool canceled; spin_lock(&ubq->cancel_lock); - if (ubq->canceling) { - spin_unlock(&ubq->cancel_lock); - return false; - } - ubq->canceling = true; + canceled = ubq->canceling; + if (!canceled) + ubq->canceling = true; spin_unlock(&ubq->cancel_lock); + return canceled; +} + +static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) +{ + bool was_canceled = ubq->canceling; + struct gendisk *disk; + + if (was_canceled) + return false; + spin_lock(&ub->lock); disk = ub->ub_disk; if (disk) @@ -1438,14 +1448,23 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) if (!disk) return false; - /* Now we are serialized with ublk_queue_rq() */ + /* + * Now we are serialized with ublk_queue_rq() + * + * Make sure that ubq->canceling is set when queue is frozen, + * because ublk_queue_rq() has to rely on this flag for avoiding to + * touch completed uring_cmd + */ blk_mq_quiesce_queue(disk->queue); - /* abort queue is for making forward progress */ - ublk_abort_queue(ub, ubq); + was_canceled = ublk_mark_queue_canceling(ubq); + if (!was_canceled) { + /* abort queue is for making forward progress */ + ublk_abort_queue(ub, ubq); + } blk_mq_unquiesce_queue(disk->queue); put_device(disk_to_dev(disk)); - return true; + return !was_canceled; } static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io,