6.12-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei ming.lei@redhat.com
[ 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 ming.lei@redhat.com Link: https://lore.kernel.org/r/20250327095123.179113-2-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/ublk_drv.c | 39 +++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index c7d728d686e5a..79b7bd8bfd458 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1416,17 +1416,27 @@ static void ublk_abort_queue(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) +{ + bool canceled; + + spin_lock(&ubq->cancel_lock); + 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;
- spin_lock(&ubq->cancel_lock); - if (ubq->canceling) { - spin_unlock(&ubq->cancel_lock); + if (was_canceled) return false; - } - ubq->canceling = true; - spin_unlock(&ubq->cancel_lock);
spin_lock(&ub->lock); disk = ub->ub_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,